HomeUncategorizedI need a perc test!


I need a perc test! — 288 Comments

    • I am not sure what you are asking, but if your property is not served by a public/private sewer system, then yes, you will need a septic system. You may or may not need a perc test, this will be determined by the local Environmental Health Department. Their decision will be based on soil conditions and proposed building size.

      Before you decide where you want the house, you need to talk with Environmental Health. I would hate to hear that your builder put the foundation in the only place a drainfield could go and thereby making the lot unbuildable.

      • We are trying to buy land. I have the soil test on file it says it 30-45 mpi. We are buying a 3 bed two bath mobile home. Will that result let a 3-2 perc for septic?

        • What can be built/placed on a parcel of land is determined by not only the soil absorption rate but also by the size of the area usable for subsurface disposal. Remember, you are also likely required to keep a 100% reserve area. That is an undisturbed area that, should your primary area fail, you could build another duplicate system in.

          It is ultimately up to the Department of Environmental Health to determine what size home you can build. Take what you have and reach out to them. You will have to anyway as they are the permitting agency for construction of the sepic system.

          • I have 10 acres, most of which is wooded right now, that I plan to put 2 houses on. One on the front 5 acres (has already had a perc done 4 years ago) and mine on the back half.
            My question is do I need to clear the proposed area of trees in order to have a perc test done? I do plan to reperc the front, in a field, when my daughter is ready to build.
            Any help would be appreciated.
            Thank you

      • I’ve built a one bedroom home on property we bought 30 yrs ago.it had a single wide trailer on it then with a septic tank.im wanting to repair the fill line or replace tank and all up to code.the city I live in.oliver springs TN doesn’t have a sewer tap for me to hook too.can I replace the tank or repair it.??thank you.

      • I’m subdividing my property to sell a parcel. Do i need a perc test or soil test to go before the county planning commission or both?

        • Before it is actually approved, it must be “blessed” by the Dept. of Environmental Health. You can do this before you begin the subdivision process or wait until the survey is done. If you choose the latter route, you run the risk of paying for survey work that may not accomplish what you want to do.

        • Is a physical perk test legally performed anymore in the state of Tennessee or is it just a Soil Scientists report that shows the soils at the location from soil web survey website?

          • Yes, to both. A soil scientist makes a soil map. If the soil type identified has an MPI (minutes per inch) rating above a certain number (I think 75 mpi), then percolation tests are required. As long as there are “good” soils, a property does not need perc tests.

    • Thinking of getting a double wide. on 7 acre. I will need a septic tank. who do I contact for septic. or what is my first step for getting a septic

    • I have a small level building spot in the woods. The home will be 1 bedroom 1 bath. I am limited as.far as level ground goes for a septic tank and field line. How much area do I need for my septic system in Tennessee?

      • That is entirely based on your soil type and its absorption rate. If you have not done already, you will likely need to hire a soil scientist to map the area so the health department can determine what is needed for the septic. Just be aware that you also must have 100% reserve. You have to have twice the usable area than is needed so you have a place to install a new system should the first one fail.

    • Unfortunately, I no longer do perc tests. I recommend you contact a local soil scientist and speak with him or her to determine if you need to have a perc test done and what they charge. It is something that can vary widely so you may want to call around.

    • Perc tests are essentially forever. I do believe there may be an “expiration” date, but if so, it is a LONG time. Now, that implies that there have not been any alterations to the land since the map and perc test were done. Any topographic or planimetric changes, whether by God or man affect the results and therefore may require a new test. This is likely at the discretion of your local environmental health department.

    • It may be possible, but it will depend on if there is any un-mapped, usable land in your lot. If they mapped all of the land capable of sustaining a septic system, then I am afraid that the only way you can get it approved for more bedrooms is to gain more land, either fee-simple or via easement, or to have an engineer design you a system to accommodate your desire for a larger home.

    • I could, but it wouldn’t do any good unless you just happen to be in the counties I work in. Your best bet is to contact your local environmental health department and find out who works in the area.

  1. i have a little over 5 acres of land and want to split it with my brother he wants it to have a big garden does it have to perk to divide my land

    • In Tennessee, if you go below 5 acres for every parcel you are dealing with, it constitutes a subdivision. You must provide adequate sanitary sewer disposal for all parcels. It doesn’t matter that he doesn’t intend on building on it, someone may want to eventually and you would have created an unbuildable lot – and a potential lawsuit for doing just that.

      • I have a customer that lives on a 3.5 acre lot and has a home currently on the property. They want to sell to a developer, but would this be feasable with no more land than 3.5 acres that already has a house on it.

        • There are too many factors to be able to accurately answer that question. Depending on the zoning and the availability of public water and sewer, one might be able to put as many as 12 houses on that land or maybe only the one. Again, too many variables to know.

  2. Hello, I inherited land with not house in Tehachapi California . I live abroad and cannot sell the land because it won’t pass the Perc test.
    How can I find a local person to prepare the land for perc testing for a reasonable fee?
    I have no way to travel to the States to do this. Can just anyone turn the land and prepare it for Perc or does it have to be a contractor or engineer which are very costly?
    Thank you in advance for helping me solve this great problem.

    • If I am understanding you, you have a tract of land that has failed perc testing? If that is the case, and you have exhausted all potential septic sites, then there is nothing a “normal” person can do. As far as I know, you cannot alter the land to make it more suitable for subsurface disposal and if you did, it would have to sit, untouched, for a very long time (7-20 years).

      The only solution I can tell you is to contact a local civil engineer and see if they have some options for alternative onsite sewer disposal systems. There are several options I have seen used here in Tennessee: artificial wetlands, low pressure pipes, enhanced filtration, etc. They are costly and they would need to be specifically designed for the site and the house that would be built. Perhaps a letter of “intent” and a quote might be enough for your Realtor to sell the land, at a reduced rate to other lands in the same area (that support conventional septic systems).

      • Hi Timothy,
        I have a house in Davidson County, built in the 1950’s. In 2010 we received a letter that it was no longer inhabitable because the septic tank was leaking. We repaired the septic tank, but this was not enough (according to Codes). They said the soil was no longer good. If there are no sewer connections near us, what other options would we have? We want to be able to rent out the house, it’s stood vacant for years.

        • Sorry, this is definitely a legal question. I have no idea what legal recourse you may have to continue to enjoy the use of your property. You will need to contact an attorney.

      • I am looking for info on using a pre existing system built sometime around 1930 or 40. It is cesspool, still attached to a home I inherited. The hime was built in 1929 and the system was still in use until 2018 when the well went dry. The home is in bad condition and we wish to demolish and rebuild. How can I find info on still being able to use the system?

        • I have not seen an active cesspool in Tennessee. I haven’t dealt with one of those since I moved out of the Missouri/Arkansas area. I don’t know if Tennessee considers a cesspool as an acceptable disposal system. You would need to call the local Department of Environmental Health.

  3. Hi, Timothy,
    I’m buying a farm in Maury county, Tennessee and asked the seller to perform a perc test.
    The results are 75min per inch. What’s the next step if I want a perc permit? All I have is a sketch from the soil consultant.

  4. Hi, I have a piece of land in Rutherford County, a Readyville address, that has a site marked at 75 MPI on an expired septic permit dated 2005 (says it was good for 3 years). On the attached map, there is only one site on the property. Someone told me that you have to have a secondary backup site now to build a home. I’m wondering what the actual rule is on that. Thanks!

    • If the permit is expired, you will need to get a new one. This doesn’t mean new testing, only paying the appropriate fees and what not. Of course, this assumes there has been no change to the property.
      As for redundancy, yes. Typically, you are required to have enough land for both a primary system AND a secondary system in the event that the primary fails. You don’t have to build it, but the land must be there for it.
      A 2005 permit should have included any need for this redundancy. There are instances where this isn’t required, but they are few and far between.

  5. I own 87 acres in Maury County that has a 2-bed cabin (living in it) while we locate a site for a bigger home. A high-intensity soils test was done in 2008, and seller stipulated that site was permitted for two 5 bed homes. Something doesn’t match up. I have tried calling the soils scientist but no response. The document is a hand-drawn page with notes am [?] is “legal”. The one house site on it says 60mpi We are so confused as to where to go next and what has to be started over. Going to try to find the county environmental department, no listing on county website! We have a survey with full GPS coordinates and just recently had important corners flagged. Help!

    • If I am to understand you, you have a high-intensity soil map (hand drawn) from some soil scientist. He/she mapped out a site to support 2 5-bedroom structures (according to the seller).
      Your next step is to reach out the environmental health department that can be found at the Health Department (http://www.maurycounty-tn.gov/index.aspx?page=69).
      They should be able to make sense out of the soil map and guide you in your endeavor.

  6. We live in Rutherford County. We currently have a 3 Bedroom home, but would like to add 2 more bedrooms. We had someone come out and find another perk site for 2 more beds, but it is on the side of the house that we now want to put the addition. Part of the addition would be directly over a portion of the perk site. My husband keeps telling me that we can’t build on top of the perk site, but this does not make sense to me. Can you please tell me if this is true, and if so, what options do we have if we want to build in that spot? We live on 12 acres.

    • I hate to go against nature, but your husband is correct. You cannot build on top of a septic system. They work by both allowing the water to absorb into the ground and to wick through the ground cover on the surface. Even if the water all went down, building on top of a drain field would compress the ground too much to allow it to function properly. If it didn’t, the resulting soft ground would not be suitable for construction.

      I am going to go out on a limb here and assume that the person who decided where to map had no idea that was where you wanted to expand. I would assume they mapped the area that would cost you the least to expand your septic system into. If you are dead set on building your addition in that place, you will need to have someone come back out and identify a different area. It will likely cost for another trip. Someone should have made sure where the house addition was going before the map was made. Not sure who dropped the ball on that – I am NOT going to point fingers.

      • We thought we found the perfect piece of land to build on but the perc site takes up more than a half an acre in front total lot just over an acre). We’d prefer not to build so far back in order to have more outdoor living space behind the house. As in the case above, could we have it retested in another spot or on a lot this size did they likely test both areas & one failed?

        • I don’t know, specifically. I can say that if your lot is on the upslope, then it is likely that they laid out the system with the intention of doing a full gravity system. You would need to talk to the Department of Environmental Health to see if any other area is suitable.

          If they did fail an area, it stays failed. Each perc test covers a 50×50 square. If there is a perc test submitted that fails, then that square is (for all intents and purposes) no longer usable.

  7. We actually were originally going to build on the other side of the house, but changed plans after he came and found the perk site, so it’s not really his fault. Thank you so much for the info. It really helps!

  8. I bought a house in Wilson County on 12 acres. We wanted to build a new home on the lower section of our property and sale our current house. I found the soil map and was curious if TrC2 soil could possibly perc for a 3 BR house or would it be a waste of time and money, requiring multiple test sites?

  9. I bought 3.7 acres in Houston County, TN and there are multiple perc sites that were done. Do you know where I can find the information regarding the results of these percs?

    • If they were filed, they would be with the County Environmental Health Department. If they weren’t filed, they will either be with the person that ordered them or with the soil scientist/surveyor/engineer/architect that performed them. If it is the latter, I have no idea how to sort that out, sorry.

  10. So I have an interesting situation. We bought our home in Davidson county and discovered during the septic inspection that the original perc test was done in 1991 and restricted the home to a two bedroom max. Yet, a three bedroom home was built. And eventually, the basement was finished out with another bedroom and bathroom added. Fast forward to today and we are updating our septic tanks and wondering if we should get a perc test done and find out if the land with our leech field has changed over the years. Could a new perc test support the additional bedrooms after so many years have passed? I’m not sure what the original owners were thinking.

    • Honestly, this is definitely a question for your local health department. If your system isn’t failing, they shouln’d be too up in arms about it. You may need to have your land remapped by a soil scientist to find a suitable area to expand the field lines. The Environmental Health Department for your county is about your only option (short of a civil engineer and lots of money).

  11. It is my understanding that if a soils scientist has said that on 4 acres of land he was able to locate only one two bedroom site that another area would also be needed to act as an alternative or secondary area before a person could build a home on that property.

    • Yes, that is basically true. However, it isn’t necessarily that only a 1-bedroom can go on that 4 acres, just that the area that was mapped would only support that. There are lots of reasons that the entire lot may not have been perced. You would need to clarify with that soil scientist (or check the soil map). Worse case scenario, you can contract with a civil engineer and see if an alternate system would be feasible (both physically and economically).

    • As I recall, a perc test is “permanent,” at least in Tennessee. Here, a perc test represents a 50′ square (2500 ft²) (see here). This means, in theory, that the area represented by a failed perc test is no longer usable for subsurface disposal. I would like to think that if an effective persuasive argument was provided, that a new perc test might be allowed.

  12. My situation is that my wife has taken care of her grandparents for the last 10 yrs and we all moved to TN. Her grandparents bought a home on 11 acres in Wilson county Lebanon TN and planned on us getting half the land and putting a home there so my wife can continue to take care of them. The problem is that we had a perc test done and the gentleman said that it cannot perc for it is suppose to be 2ft soil and only has 1 ft of soil. My question is is there any other way or anything else that can be done to get a house out there? Thank you.

    • If your soil scientist has stated that there is not adequate soil on 11 acres for 2 houses, then your next recourse would be to contact a civil engineer and discuss alternate sewage disposal options. There are several options, like recirculating sand filtration systems, constructed wetlands, and others. All of them will need to be designed by a licensed engineer and approved by the Department of Environmental Health.

  13. I live in Wilson county,is there a limit to how far away I can build my house from the perc site of my property if I still plan to put my septic system on the perc location?

    • I don’t know that I have ever had this issue. As far as I know, you can pump your effluent as far as you want. We have worked with on-site sewer systems that were essentially communal drain fields. They collected the effluent from all of a subdivision and use a central drain field. The issue you may run into is pipe and pump sizing. Too small or large of pipe or an undersized/oversized pump can cause other issues. For this, you may want to talk to an engineer or an expert at a plumbing supply store. Most manufacturers can size your pump and pipe for you, given the correct information (rise/fall, run, usage, etc).

    • To my best recollection, a perc test is “permanent.” Essentially, if the land has not been modified since the test, then the passing results stand. The same goes for failing. Submitting a failing perc test to the health department makes a 50-foot square, centered on the hole, non-usable for sub-surface disposal. You cannot retest a failing hole. However, you can move over a few feet, dig a new hole, and test that hole. Also, if you are in a dry season, you are more likely to get desired results versus a wet, saturated season.

      To answer your question, if you have not submitted the holes to the Environmental Health Department, try all you want. If you have, you basically have to abandon that square and try another area.

  14. My house was built in 2004, it used to be farm land, I’m having issues with my septic tank, the next door neighbors land is slopped towards my property and the water run off is flooding my yard. the soil is red clay and i do not believe it is perking properly. I purchased the property 2 years ago and have had this issue since, but it was not disclosed that there was septic issues in the sale, is there any way that the builders could have slipped by or not done the correct perk test for the type of soil I have? If so what type of actions can I take to resolve this issue seeing as it is preexisting from the builder/previous owner.

    • “is there any way that the builders could have slipped by or not done the correct perk test for the type of soil I have?” Absolutely they could have slipped by. Was that the case? Who knows or would ever know. However, the builder cannot do the perc test. It has to be done by a soil scientist or surveyor. They may not have installed the system properly, but they are usually inspected by the health department. It is possible that they didn’t install enough line for your size house (it happened on mine). It is also likely that runoff from the neighbor is infiltrating your drain field and saturating it.

      Talk to the local environmental health department and find out what they recommend. One thing you can do is install something (an interceptor ditch or berm) to prevent the runoff from getting to the drain field. This may alleviate the problem. In the end, it will come to the health department to make a determination.

      As for lack of disclosure, that is a legal issue and you would need to speak to an attorney on that matter.

  15. I have a neighbor who is apparently dumping sewage out [the] side of their property. Is this legal? What can I do about it? DeKalb County

    • My first call would be to the neighbor. A peaceful resolution is typically better than reporting and subsequently firing the first salvo in what may turn into an all-out “war” with your neighbor. After that, the next stop would likely be the Dekalb County Department of Environmental Health. If you don’t get any satisfaction from that agency, you can escalate to the Tennessee Department of Environmental Health. All of these are dealing with subsurface disposal (theoretically).

  16. My boyfriend and I are wanting to build a 1000 sq/ft shop/apartment (1bd/1ba) adjacent to his grandad’s home. The house was originally built in the 50’s when no codes or standards were quite in place. This will be a temporary housing so we are curious about the procedure to go about.

    We have a few questions and haven’t quite found someone that could answer them.

    1. Will the whole property, including his grandad’s house, have to be reperced for us to build?

    2. If we called it a non-dwelling residence, would a perc site be needed?

    3. What is the likelihood of being able to tie into the existing septic tank of his grandads house as it was never perced?

    4. Is a perc needed BEFORE a pax is comstructed? Before? During? After?

    5. Aside from the calling the slim scientist, is there anything else that needs to be done on our end prior to this?

    • 1. Will the whole property, including his grandad’s house, have to be reperced for us to build?
      If there is no permit on file, it is likely that you will have to have the existing system inspected. Then, you will either need to expand (assuming it isn’t large enough) said system to cover the additional usage or construct a new system. You will need to have soil mapped areas for these options.

      2. If we called it a non-dwelling residence, would a perc site be needed?
      If you want to build with a permit, you will have to show the bathroom. If that exists and ties into the existing system, it doesn’t matter what you call it, it will need to be evaluated.

      3. What is the likelihood of being able to tie into the existing septic tank of his grandads house as it was never perced?
      I dont’ know, this will depend on what was installed and if the health department is capable of ascertaining the elements of the existing system.

      4. Is a perc needed BEFORE a pax is comstructed? Before? During? After?
      I am not sure what you mean by “pax” but a perc test is only needed if the soil type requires it. If it does, you need to do the perc before you build. What would happen if you built the garage/shop/apartment and then couldn’t install a bathroom/kitchen because you haven’t the soil to dispose of the wastewater?

      5. Aside from the calling the slim scientist, is there anything else that needs to be done on our end prior to this?
      Your next step is to contact the Dept. of Environmental Health for your area. They should be able to pull the records and see what is needed. I would also suggest contacting your building codes department to ensure this is even legal in your area. Some zones will not allow an additional dwelling on the property.

  17. I have 16 acres of land in Cumberland Country and a soil test failed. Who should I call to do a perculation test. I have contacted many surveyors who say they do not do this. I don’t know where to turn next. Would it make any sense to have another soil test done on another area of the property. I need help. Thank you

    • I would suggest you contact the soil scientist that did the original map. (S)he should be familiar with it and would know where to get the needed usable land for a system. One cannot randomly perc test land and claim it is usable.

  18. We have been in the process of getting our home approved for an alternative perc site through the Williamson County Sewer department (a Williamson County regulation). However this has been going on for 3+ years. We have been working with the county and following their procedures. After 3 failed perc test our latest recommendation from the county was to contact an engineer, surveyor and soil scientist to prepare alternative system option to present to the Board of Health.’ Our sewer lines were cracked through the process by either the surveyor or the soil scientist. After another costly repair we finally turned in everything to the county and waited 2 weeks before following up with them to find out where we stood in order to meet with the Board of Health. The representative at the Williamson County Sewer Department who I’ve been working with for the past 3 years and getting this process to this point stated “I simply don’t know” “I don’t know what your next processes'” Seriously???? Who do I contact on a state level to report the extreme prejudices faced by Williamson County residents when it comes to getting perc test processed and approved and the multiple delays that occur. Unfortunately it is known that Williamson County is very difficult to work with, is extremely slow in their processes of approval, and is very biased with who they are willing to serve and make a priority. However as a government agency I feel that they are employed by the taxpayers and should be more efficient in their job and not be so biased in their approval process and procedures. I feel like they need to be reported to the states governing agency in order to not abuse their practices and position. The sadest part about this is that our home is perk for 4 bedroom and that’s exactly what we are going to have in this home. But the law states that if you are adding on ( we are wanting to add on living room space) we are required to have a backup system. We living on 11.5 acres….. House was built in 1980s, the field lines are in the neighbor’s yard and were never surveyed properly when the property was divided and sold. The land that are field line sit on was sold illegally. I’m getting so frustrated with a “good old boy”system.

    • You claim “3 failed perc test[s].” This would mean that there are 3 holes in the ground that encompass a 50×50 square each that cannot be used for a drain field. Given your acreage, I would assume there would be more land out there somewhere you could use. However, you cannot use land that has been disturbed or is much over a 30% slope. Also, you have to stay away from drains, gullies, and other ditches.

      If your soil scientist (the only person in the state) has mapped the entire 11.5 acres and was not able to find suitable land for the 100% reserve area that is not required, then your next option is to contact a civil engineer. This is to determine if you can use an alternate system. These are designed by the engineer and are signed off by them. They are then outside of the County Environmental Health Department’s purview. However, you still have to get them on board with the whole thing. (It is messy) The issue with alternative systems is that they are not cheap. Not the design nor the installation.

      As for reporting the Williamson County Department of Environmental Health (I assume that is who you are speaking of), the only recourses I know of is to get in touch with the Tennessee Department of Environmental Conservation (TDEC) and talk with them or you can contact the County Mayor or the Attorney General for the State of Tennessee.

      I am not sure how a surveyor would have “cracked” your existing lines, but I guess it could happen.

      As to the last segment when you said, ” House was built in 1980s, the field lines are in the neighbor’s yard and were never surveyed properly when the property was divided and sold. The land that [our] field line[s] sit on was sold illegally.” It is possible to sell land with encroachments on it. It is not illegal to do so. It is not the responsibility of the encumbered landowner to secure an easement for the enjoyment of another. That is on the person who is encroaching. The builder/homeowner should have secured an easement for the drain field. If they did not, then the lines are encroaching illegally and the landowner could (in theory) cut them off from your home. It is their land.

      However, if your drain field is on someone else, it sounds like your property may not be very suitable for a septic system to begin with. Contact your soil scientist and have them explain to you why they cannot find suitable land for the reserve area. It shouldn’t matter if it is in the back of your property as long as it is feasible to install and service (with a pump if need be).

  19. My husband and I have almost 3 acres, we had the lands soil tested and they said we can only put a two bedroom home there but we.could tell the guy to write it is a 2 bedroom one bath on paper work when we get it and it’s bigger. Is this possible if not what is the next step to trying to get it approved for a bigger home.

    • If I am understanding, you had the property mapped and the health department said it only approved for a 2-bedroom residence. Then, you are saying that you could get the permit for said 2-bedroom and build bigger? You could, but then you could also not get a certificate of occupancy once you have finished building.
      If you want a bigger house, you need to talk to the soil scientist and see if there is any other land available that wasn’t mapped. The other option is to talk with a civil engineer to see if there is the potential for an alternative system, like a sand filter or constructed wetlands or an LPP system or whatever.

      • The guy that did the perc test said he checked all overthe property and one spot passed but only for a 2 bedroom one bath. Bit he told us to not to worry about size of home we put out there. So when we put a a trailer out there will it say on paper only 2 bedroom or will it say passed or failed and we put a bigger trailer if we want to. We just don’t want to buy a 4 bedroom 2 bath and when they bring it out to set up something goes wrong for some reason they are not Able to by the words on the test.

  20. Hello, i’m looking for answers for an alternative system in Rutherford co.. 5 acres. only 10 inches of soil in a very small 12×5 area on the property. any recommendations?

    • You would need to contact a civil engineer. If one doesn’t know of any alternative systems, try another. There are several out there, but you will have to have one that is specific to your needs and conditions and I am not an engineer, sorry.

  21. Aside from a conventional septic system with a leachfield is there another option that would be up to code? I am looking to build a second home on my 45 acres and I am told that at one time the neighbors had to run their septic line all the way onto my property in a lagoon type situation. Not sure if I understood that correctly. It is not far from where I want to build the new house. It is no longer in use but I wonder if I could hook into that and use it for my second home? How would I find out more about this spot, it must’ve been approved as being up to code as some time since they were able to build their house. Would their be a record of it somewhere? And did I just misunderstand, is it just simply a leachfield with a fence around it?

    • First, a lagoon is a pond that holds your effluent (runoff from the septic tank). In theory, it would allow slow absorption into the ground but moreover, it would allow evaporation of the effluent.
      I have not heard of a lagoon being employed in recent history. Actually, I have not seen a lagoon since I worked in rural Missouri in the late 90s.
      I doubt you would be able to use one now unless it was preexisting attached to a preexisting house. You cannot typically connect to an existing system without a full inspection of it to ensure that it meets current codes.
      Now, as for building and using a lagoon, it may not have ever been approved. Depending on how they went about building, they may not have had a building permit, or, in some areas, got a permit but didn’t ever have inspections (no inspectors). Or, they got the permit, didn’t install correctly, and never got a final approval from the Health Department.

      Nepotism is also a thing, so there’s always that potential situation.

  22. What training and qualifications are required to provide perk test services for others?
    I have a nephew that is very interested and there seems to be a real need in our area.

    • In order to perform a perc test, one must be a surveyor, engineer, soil scientist, or architect. (I don’t get the last one, but it is that).
      I had a friend that had worked with a soil scientist performing perc tests. The soil scientist then signed the reports, much like a surveyor having a field crew.
      If your nephew is interested in becoming a soil scientist, you can look at Tenn. Code Ann. § 62-18-208 for the licensing requirements.

  23. HI, I have a soil test from 2002 with a rating of 75 mpi (wdd) based on a field line installed 24-28 inches in depth and a drain down drain installed around field lines.

    What does that mean?

    I am selling the land, should it pass a perc test?

    • Hi Julie,
      If you have a soil map with this information, you may also require a perc test, but I am guessing you don’t. This map is stating that you have the ability to install a system but it will need to go to the county health department for consideration to establish how large a home is needed.
      As for passing a perc test, that has too many factors to determine. I will say that it is usually easier to pass a perc in dry weather when the soils are not saturated.
      Take your map to the county department of environmental health and talk to them. Find out how large a system you can expect (they likely won’t tell you specifically without filing for a permit).

  24. My wife and I are considering the purchase of a home on 5.88 acres that has a septic system and pproved for 3 beds. We’re a 5 person family, and would need to make a basement room an additional bedroom for one of the kids. Generally speaking, shouldn’t the current septic system be able to accommodate our needs?

    Also, what sort of issues emerge with overuse or improper usage of a septic system?

    • Any time you expand a house that is on septic, you should contact the local health department as to the necessity of expanding the drain field.
      Theoretically, a system would likely be designed based on two people per bedroom. A three-bedroom structure could house 6 people. Whether or not yours was done this way, I don’t know. Remember though, if you add a bedroom, you then have a house that does not have an adequately approved septic system and that could impact your ability to sell, refinance, or many other issues.

      Now, as for what issues can arise, that is a question for a plumber. I can tell you that I had a house where the drain field stayed wet a lot of the time. This will eventually stink and make for a nasty yard. Our slope was such that the effluent ran off rather than pool, but it was still soggy and muddy. It can also back up into the septic tank and can consequently back up into the lowest drain in the house. All nasty and undesireable.

      Best action is to contact the department of environmental health and determine what need be done to make it be compliant.

  25. I am looking at a property for sale in a subdivision that has been around a very long time in Knoxville. All of the properties are on septic. There are a few land panels for sale, one of them we are interested in is about 3 acres. Surrounded by other homes with septic. Realtor says not approved for septic. I called health dept and they looked up the three addresses for the parcels of property and told me they were surveyed in 2003 and found not approved….I believe because of rock issues? I asked if I could have it re looked at and they said it would not do any good. Are there any other options? It seems odd that this one property would not be approved. I don’t mind paying an engineer to retest if that would do any good in getting an approval or confirming that the entire property is not suitable. Thank you!

    • There are some other, alternative systems that may be possible. You should talk to a civil engineering firm, like Batson, Hinds, Norvell, and Poe. They can address some of these questions better than I can. The land may not be suitable for sub-surface sewage disposal, but there may be an LPP or constructed wetlands, or another system it is suitable for.

  26. My family owns some land. They are going to deed us an acre to build on. I’d like to know if it will perc prior to even getting it deeded over to us. Can we have the test done prior to it being deeded in our name and prior to having a building permit? Since land isn’t in my name, could my mother (land is in her name) have the perc test done with out any type of building permit? If it won’t perc, we won’t buiid there. Don’t want to have it deeded over to us if we aren’t going to build there.

    • What you are actually looking for is a soil map. You need to have a high-intensity soil map made by a licensed Soil Scientist to determine what the feasibility of a subsurface disposal system is. Now, to answer your question, Yes, you can have this done prior to deeding off the land. In fact, I would recommend doing this first. You don’t want to pay for a survey if the land can’t support a septic system and only the soil map will determine that.

      Contact your local environmental health department and get a list of soil scientists that work in your area.

      • So I am in a similar situation as the original post/comment. Hopefully you can steer me in the right direction.
        My family has 5 acres and planned on deeding me 3 acres to build. It’s overgrown with brush and saplings. On the land, the TVA has an easement for powerlines and a small wetlands area. (We just noticed this recently.) My questions are:
        Do I have to have the land cleared before having the perc testing done? *We don’t know where exactly we want to build, just somewhere on the 3 acres. Not sure if we have to figure that out first or not*
        Will the wetland area effect anything if I build farther away from it?

        • The wetlands should not affect your septic system as long as you are not right on top of them but check with the local Department of Environmental health on that. You may be able to construct your septic system in the power transmission easement, but I am not sure. It would depend on how the easement was written.

          You don’t have to clear for the perc testing, you just need to know where you want to build so you are not mapping the whole property and not mapping something too far away from your site.

          • Hey Timothy, I hope you are doing well. Thank you for your reply. In your experience, do you know if the TVA and/or whomever does the wetlands may have done any types of testing that would be on record still? Soil testing, property lines,ect? Is that something the environmental health department may know? I figure if they have done any tests that may save on me having to do them, it could be helpful. Just a thought.

          • I am not sure what you are looking for but if there is anything regarding a septic system on file, it would be with the Health Department. TVA only deals with their land. If you have a wetland on your property, it would likely be under the purview of the Tennessee Department of Environmental Conservation. You may have a local, county office as well.

          • One more question 🙂 I have searched for environmental health department in White county, but it only shows the health dept. Should I be looking for something different? Would the property assessor know where to direct me?

  27. We are looking at buying a 10-acre tract of land that has no record of perk testing being done. Before I was comfortable to buy the land, I wanted a soil scientist to come out and evaluate it, with knowledge of where, specifically, we were going to build. Upon meeting him there today and his evaluating five different sample pulls, he told me that the land would absolutely need a perk test. With this knowledge, I am wondering if it indeed is worthwhile to even move forward with a ‘Perk test’, which I understand can cost upwards of $1500 based on number of holes dug/tested.
    The guy has been a soil engineer for 30+ years, so he knows! Is it still possible that soil perks despite it being a non conducive type of soil? Thank you!

    • From my experience, bad soils (like Dandridge or Talbott) can perc, but they don’t always. You can look up the procedure (here is one place) and run a few of your own. Just know that your tests will not be binding. However, at least you will get a feel for how the land will percolate.

  28. We are looking to buy land in DeKalb County TN which has 22 acres with one 2BR house already on the property. We want to parcel off 5 acres for our son but need to determine whether it will perk for another home. Is there a way to tell if it perks or has been perked without paying a soil scientist to come do it? I keep seeing some of the comments about a soil map? Does that tell if the land has been perked? And, if so, where can you see this soil map? Thanks!

    • There are some old, low-intensity soil maps floating around, but I am not sure if they will help you specifically. You can talk to the local Department of Environmental Health, but I am going to guess that no one has had that done before – at least, not done and submitted to planning. Everything else is private so it would remain in the hands of the previous owner or the soil scientist.

      If you really want a free method of pre-determining (non-binding on the county/city) if your land will perc before you spend the money on a soil map, you can do perc tests yourself. Here is a draft of the Soil Handbook that outlines how to do a perc test.

      It only requires post hole diggers, water, a tape measure, and time.

    • I am not sure what that stands for either. Unfortunately, there isn’t any “standard” for acronyms or abbreviations. Theoretically, one should not use one unless it is established what it means. I wish I could help more.

  29. After I originally left a comment I appear to have clicked on the -Notify me when new comments are added-
    checkbox and from now on every time a comment is added I recieve four emails with the exact same
    comment. There has to be a way you are able to remove me from that service?

  30. Hello,
    We are soon getting a perc for a septic use and how many we can have (developing purposes). My question is, there are many septoc systems, if it fails can I not use a better system to still be able to build more? Also, dry creek, creek is on the property…can we not use the creek in to drain the septic?

    • No, you cannot use a creek, dry or not, to drain the septic. You must use an approved disposal method. There are alternatives available if your land doesn’t perc as well as you would like, but these all require to be designed by an engineer.

    • Perc tests typically take 24 hours to do (not counting digging). How long it takes to get the results back would be up to the tester. It isn’t a difficult form to complete, but sometimes you just get behind.

  31. My son bought 3 acres in coffee county that came with a perc
    Test /Soil map it’s black and white. 1,who keeps the original map 2,there seems to be 4 spots that are marked how do we make sense of them. He plans on building a shop with living qtrs and will only call for 1 bed 1 bath but before he starts to clear and put in driveway I want him to understand how this works so he don’t have to go backwards.

    • You would likely need to contact the soil scientist that did the map. There are no mapping standards so you are at the mercy of the cartographer as to what means what.

  32. Hi, We are wanting to buy a piece of land in Williamson county. The real estate agent says there has been a preliminary perc test done, and it shows the ability to build a 3 bedroom house on the land. He suggests we have another perc test done. Is that necessary? What does he mean by preliminary perc test?

    • God only knows what he means by “preliminary” perc test. I would ask for any paperwork and results. You will likely need an actual soil map. I am not sure if Williamson County employs a soil scientist or if you are responsible for hiring your own. I would check with the local Dept. of Environmental Health and see what they have on the property. This would give you a good idea where you need to go and if you can even build what you want.

    • I am not familiar with a “STEP” system. If you are disposing of the effluent onsite, you would likely have a soil map done. If you are pumping the effluent offsite, then no. It is possible that you could have either a community drain field or your effluent is heading to a sewage treatment plant of some sort. In all, if you are not getting rid of the effluent on your property, then no, you don’t need a perc test or soil map.

  33. I had another Realtor tell me on 30+ acre property in Dickson…you didn’t need a perc test, you could tell the county what you wanna build and they just give you permit, and that anything over 5acres didn’t need a perc test???…that does not sound right to me…

    • When dividing land, you do not have to have health department approval, provided all tracts are at least 5 acres. When you decide to build, you must file for a permit for a subsurface disposal system (septic) and at that time, the local health department will determine if you need a soil map (assuming one was not done prior) and based on the soil type, you may or may not have to do a perc test. As far as I know, Tennessee requires a permit for all subsurface disposal systems and that requires knowing the percolation rate of the soil it is being installed into. This identification must be performed by a licensed soil scientist.

      Perhaps you should talk to a different real estate agent – this one is asking for a lawsuit.

      • I have a similar question. See were told by the realtor that two other lots had already perked. We bought the property next two those lots because he said we should have no problem perking because the other lots did. Our land failed. I do think that they did the test at the wedding time as it has been raining but I’m curious if we can legally hold the realtor responsible here since we went off his recommendations. My other questions are about alternatives. Can we live in a dry cabin legally and not have to get a septic at all? Can we have water on the property, but as long as there is no plumbing in the house it’s still considered a dry dwelling? Are outhouses or composting toilets and option in Tennessee?

        • You are delving well into areas that are going to require information that is well above my pay grade. An engineer can likely help you with the options of alternative sewer systems. As for legal action, anyone can sue anyone for anything, but would you win? I don’t know. You would need to talk to an attorney about that.
          As for a “dry” cabin, I have never heard of this. I would suspect that it may be possible to do something like an outhouse or composting toilet, but you would need to talk to the department of environmental health on that.

  34. I’m very confused, and not just by my strokes. A friend and I have a nearly 16=acre plot of mostly-forested land near Lewisburg we were going to build on, but we ran out of money and time. So we put it up for sale. An offer is contingent upon viability of the perk sites, the last test was done in February 2015. That soils engineer is too busy to recheck it, but he says that for a 4-bedroom home our property should have 12,000 square feet of drainage area. It’s confusing because everything I’ve read (from the TDEC web site) indicates 370 square feet per bedroom. So I guess my question is, are there alternatives? I’ve heard of the “mound” system. The land does slope downward from the proposed home site, and the 2015 perks show a rate of 50-75 mpi. We’d really like to have good suggestions we can offer to the buyer! Thank you.

    • I don’t believe 50-75 minutes per inch absorption rate soil even requires individual perc tests. Given the rate you quoted from the TDEC website and the 4-bedroom stip, you would be closer to 1200 ft² rather than the 12,000 ft² you were quoted. You may want to just be sure someone didn’t inadvertently add a zero. I would suggest talking to the local Department of Environmental Health. If you have the high-intensity soil map, take it in and talk with the people responsible for laying out the system and see what they have to say. If the size is still way up there, then contact an engineer to determine the best alternative system. In the end, it is the job of Environmental Health to determine system size, not the soil scientist.

    • No idea. You would need to talk to someone that does them and in that area. Contact the local Dept. of Environmental Health and see what soil scientists work in that area.

  35. Can a barn built on a concrete pad be built without perk permit in Rutherford County, TN? I rescue all types of animals and have 5 acres. Hoping someone knows options. Supposedly I do not need kennel license and have the blessing of certain officials, just I am wondering if others have bought Morton buildings without any type of perking requirement? It would be built on a ROCK basically, lol. All the drainage would be recycled sand system to properly be self sustainable and clean.

    • A barn isn’t a problem. The issue is if you want to include a restroom. If you do, you have to deal with the Department of Environmental Conservation. If you are choosing to use an alternative system, then you will likely need to have that designed by an engineer.

      Whether you need a perc test or not will be dependant on the soil type as well as the type of system you intend on installing.

  36. I have a soul site and someone pulled out the steaks marked. I called the man whom did the job in the first place, I have the paper work in hand ok so he said it would be 800 dollars to come out and put the sticks back in the right place mind you he has been payed 900 for the job, by law can he charge me what ever he wants to Re-steak the job it seems to me he’s ripping me off and pisses me off that he would do that

    • If the person completed the job and someone destroyed the monuments, yes, he is well within his rights to charge whatever he wants. It is not the responsibility of a surveyor (or anyone else for that matter) to protect and replace corners when they are damaged or removed.

      If you are not happy with the fee he is asking, you are more than welcome to hire someone else.

  37. We have 8+ acres in Montgomery Co. and would like to subdivide off 2.5 acres and build a1500sf two bedroom 2 bath cabin. The site sits 100 yards from a year round small creek and is located on a small hill. Looking at the100 year flood plan map it is also 15 ft. in elevation above the indicated flood zone level. The property overall slopes gradually towards the creek. The area is somewhat rocky. How would that affect a perk test? How far from the creek can a septic system be installed? What specific requirements or issues apply in this situation? Thanks for your thoughts.

    • It has been a day or two since I laid out a septic system. I believe you must stay 25′ off the top of the bank of the creek (see https://www.williamsoncounty-tn.gov/DocumentCenter/View/1971/WC-regs-cert—Dec-2009?bidId=).
      As far as I know, the 100-yr flood does not have an effect on the ability to install a subsurface disposal system.
      Soil types are different all over and would require a high-intensity soil map. If the soil scientist determines that the absorption rate listed for the soil type is too high, they may require a percolation test. If the soil is rocky, I had been known to charge more for the test (only because it was difficult to dig).

      All systems in Tennessee must be approved by the Department of Environmental Health before installation. Please reach out to the one in your county and see what they want, specifically.

  38. I’ve been looking over your forum and appreciate all the info. I am currently looking to buy an acre privately for a homesite in Macon county. This is with terms that it perks. My dilemma is according to what I’ve found out the land must be surveyed and zoned before a perk can be done. In this scenario the landowner doesn’t want to be out the expense of the survey and recording the platt if he can’t sell it, and I on the other hand don’t want to purchase it if I can’t build on it. My question is could we solicit a qualified person that does perk test officially, to do an unofficial perk so to speak. My understanding is that all perk test are done by outside sources. Any advice and thoughts are appreciated.

    • There is no obligation to have it surveyed before it is evaluated for a subsurface disposal system. Contact a local soil scientist and explain what you are trying to do. Everyone I know would happily do a cursory soil map to ensure you are getting what is needed to install a septic system. In fact, in risky soils, it is best to have it done before you divide so that you don’t end up redividing it.

      Now, you cannot get a permit for a specific acre if you have not created that parcel and perhaps that is what was alluded to.

  39. We recently purchased approx 80 acres in Auburntown,.TN We have a map that says “boundary/division survey” dated 2008(((by Long Engineering out of Nashville))that the realtor gave us. The map labels 3 different soil sites on it and the realtor stated “those are the perc sites”. We will not be building for another year and I know we have to get a perc permit but just by going on what I said do we have to have them perc tested again??? Soil sites never expire??? Just confused –we don’t want to make forever home plans and these not be actual perc sites..Thank you in advance

    • Assuming you have a soil map (which it sounds like you do), then you are good. Provided that the surface isn’t altered (grading, deforesting, etc), a soil map is permanent. It isn’t like the soils are going to change over time.

      Now, if the soil scientist who did the map were to be found to be negligent, it may require a new map, but that scenario is highly unlikely.

  40. I know I can build a house on my land but can I build on it for commercial purposes? Are there different stipulation for commercial vs. residential?

      • See above, but I would have to wonder why you cannot build. If it is because you cannot put a septic system on it, then you would likely not be able to put anything that requires you provide a restroom. The only things I have seen around here built on sites without septic are storage units.

    • This will come down to your zoning and any restrictions placed on the deed (Homeowners association, etc). Contact your local zoning board and determine what your property is zoned and what is allowed in said zone.

  41. I’m looking at buying some property and building on it in 2-4 yrs. It is large cleared pasture/hay field on top of a ridge line. The soil map I found on line shows most of the cleared pasture is either Clairborne silt loam or Fullerton cherty silt loam, hilly phase. Based on that and Appendix 1 of RULES
    REGULATIONS TO GOVERN SUBSURFACE SEWAGE DISPOSAL SYSTEMS, the soil absorption rate is 45 for both soil types. Am I correct that this would not require a PERC test for an underground septic system? Would I need to proved that via testing or is that soil map and reg sufficient to not need a PERC? Thanks

    • To get a subsurface disposal (septic) permit, you will likely need a high-intensity soil map. If the soil map you have is that, then you are likely good to go. If it is other than that, you would probably need to hire a soil scientist to make one. Assuming the soils are what the map shows and the absorption rate is below 75, I believe you are right and will not be required to do a percolation test to apply for a permit.

      • Thank you for your quick and helpful response. The soil survey map I have is from AcreValue so I don’t know if it is a high intensity map or not. Not being my area of expertise, I wouldn’t be able to tell the difference. It is a fairly detailed map showing the zones of different soil types for each section of the property. Can you recommend a soil scientist near the Tazewell area? In general the portion of the property in question is an open rolling 40 acre pasture plateau. Is having a high intensity map made a costly proposition? Thanks again for your help!

      • And if it helps, the soil survey map I have does designate which portions of the pasture have what specific soil types. There are 3 different soil types in the pasture areas, but the two I asked about would be the section of acreage that I would be using for disposal system

  42. We are looking at a 5 acre tract to purchase and the environmental notes and map show a 3 bedroom perc site area. The following statement is included: “Tract is approved for a maximum of 3 bedroom residence with use of a conventional subsurface sewage disposal system. Final approval of the subsurface sewage disposal system will depend upon the successful construction and approval of curtain/interceptor drains installed at a minimum depth of 36″, encroachment upon soil area will result in loss of bedroom approval.”

    Does this mean that we would have to install a septic system that is specialized; therefore, a lot more costly than a conventional system (since it mentions curtain/interceptor drains)? What type of system is that and what is the average overall range of cost for a normal septic vs the one that this property is requiring that sounds like some sort of alternative system? Thank you for any guidance that you can provide.

    • Curtain/interceptor drains are also known as “French drains.” They are installed uphill of the septic system to catch the surface (and subsurface) water and divert it around the drain field to prevent runoff from infiltrating the system and saturating the land.

      Not exceptionally expensive but more costly than if you didn’t have to have one.

  43. Thank you for your quick and helpful response. The soil survey map I have is from AcreValue so I don’t know if it is a high intensity map or not. Not being my area of expertise, I wouldn’t be able to tell the difference. It is a fairly detailed map showing the zones of different soil types for each section of the property. Can you recommend a soil scientist near the Tazewell area? In general the portion of the property in question is an open rolling 40 acre pasture plateau. Is having a high intensity map made a costly proposition? Thanks again for your help!

    • I don’t know of any soil scientists that work that area, but your local department of environmental health should have a list. They can also tell if you are good or if you need more soil work.

  44. If there is an existing septic system being used for a mobile and we ant to replace the home with a newer one, will another perc test be required or is the existing septic system ok to be used?

    • It is likely that you may not need another perc test or soil map. However, you will likely need to have the Department of Environmental Health make that determination. They may want to inspect the system and may require that you have the area for an emergency reserve.

      Also, if you are increasing the number of bedrooms in the new home, then your existing system may not be adequate.

  45. I am looking at buying a completely ‘wooded’ 5 acre lot to build a house on. These are all kind of the same question, but I wasn’t sure the best way to ask it:

    Do I need to have the proposed building area cleared before I have the DOEH come out to do a perc test? And wouldn’t the process of clearing out a wooded area disturb the soil? How do you build a drain field in an area that was previously wooded?

    • If the building site is excessively thick, it is possible to grub out the underbrush, but if you full clear and it turns out that is the only usable soil, then you are likely screwed. Let the Health Department sort it out first. They may want the house site staked out though.

      Clearing can definitely disturb the soil. As for installing a system, I believe that those must be done by an “approved” installer. The should know how to snake the drain field around trees and what not. Here in the Gatlinburg area, our builders leave every tree they can so septic systems are built among the trees.

  46. We have a property we are wanting to put multiple houses on. We need to see how many sites the property is capable of having. How do we do this? Who do we call for Coffee County TN? TIA

    • There are several “steps” and those will depend on how you want to deal with this. Are you going to build on a single tract or are you going to divide? Either would start with a conversation with a surveyor. They should be familiar with the local zoning requirements as well as subdivision requirements.

      You will also want to talk to a soil scientist to see if the land in that area can support what you want to do. A cursory review should be sufficient to give you a maybe vs a not-at-all. Finally, a meeting with planning and zoning as well as the Dept. of Environmental Health would be good to be sure everyone is on the same page.

  47. Timothy, thanks for the great information on this site! Very helpful grounding in what’s needed. A couple of questions if you don’t mind. First, if an extra high intensity soil map has been done for a property in Williamson County, how do you know then if a perc test is required or not to apply for a permit? Second, if the parcel is large enough, is there any restriction on the number of septic systems and fields that could be installed on a single 24 acre parcel? The ultimate question is if we built a garage with a bedroom and bathroom above it on a separate part of the property from our house, is there any reason a second or third septic system couldn’t be installed to support that building on a different part of the property (assuming the soil could support it)? Final related question, can separate buildings within some proximity share a septic system, or are there any regulations on sharing septic systems between buildings on the same property? I assume that is only a matter of distance for feasibility? Thank you.

    • First, it is not uncommon for entire neighborhoods to use a shared septic system. Your limitation would be on distance and cost. If the available soil is limit or if you only want a single drain field, you could pump the effluent to it from wherever is feasible (pump strength, line length, etc).

      Now, the high-intensity soil map will determine the type of soil along with the absorption rates of those soils. If the rate is less than 75 minutes per inch (mpi) (see TDEC Rules 0400-48-01-.07(c)), then a perc test is not needed.

      As for the number of systems/building/habitable stuctures/etc… This will be a mixed issue. Theoretically, if the land will support it, then there is no reason that the Dept of Environmental Health couldn’t approve it. If the single drain field exceeds a certain size, then it may require an engineer to sign off on it. The other part of the mixed issue is zoning. Although the soil may support it, the county may not. In Jefferson County, TN, you can only have one habitable structure per piece of property, no matter the size of it. Others have no restrictions. Some don’t restrict a garage apartment while some do. That is a question for Zoning and Codes Enforcement.

      • Thank you for sharing all of this knowledge and the info you have shared. I am just starting to research about septic sites and perc requirements. My father, brother, and myself are all wanting to purchase some land together and a couple years down the road build us a house on it. It’s looking like it could be an endeavor to find a piece suitable for three perk sites. Just going off ppl having trouble getting one in places. I read it is required to have a backup site as well. Does that mean we would have to have 6 perc sites? We have found a piece of property we would like to make an offer on contingent on it perking obviously. The only thing is the front where we would all prefer our houses is kind of Rocky in places. But also has great big trees in it too. And the back portion is more woods and a nice field in the back. Soil type from just online seems to be Eg,Trc,tbd3,tbc3 would you know if any of those would normally perk? Looking in Rutherford county specifically. We would be purchasing land together as a whole would land have to be divided before building could start? Which wouldn’t be a problem but I guess we could split off 5 acre tracts and keep the other about 35 acres together. But if so could we give each other an easement for septic if needed? Thank you for sharing all your wealth of knowledge to help others gain a better understanding.

        • You have a couple of things you have brought up. First, let’s talk about that division. Provided all parcels are 5 acres or more, touch an approved road, and don’t require piping in water or piping out sewer, they do not fall under the purview of the planning commission. Now, if you keep everyone above 15 acres, each one can put the land into greenbelt and reduce the amount of taxes you have to pay. If anyone is going to finance their construction, I would suggest encumbering the least amount of land as possible. That way, if someone loses it to the bank, the bulk of the land is still safe.

          Now, on to septics. I am not familiar with those soil types. Every region has it’s own and besides that, I am not a soil scientist. It has been my experience that if there are large trees, the soils are usually pretty good for sub-surface disposal. I would recommend getting a soil scientist to look at the land before your inspection period runs out and get their take on it. Even without a high-intensity soil map, the soil scientist should have a pretty good idea about what you can do with the land.

          You can grant easements as needed, but they then become issues if one of you decides to sell and the others don’t like their new neighbors. Either way, it sounds like you should be able to find suitable soils to install a system into. You may or may not require percolation testing, but you will likely need to ensure that you have enough land to install twice the amount of drain field than is needed for the house. This allows for the 100% reserve. It can be adjacent to the primary drain field or can be somewhere else entirely. All the reserve must have is suitable soil. It doesn’t matter if you may have to pump for that one, you don’t have to build it. You just have to have a place to install a new system if the primary one fails. So technically, yes, you do have to have 6 usuable drain fields…

          • Thank you for your info. It is greatly appreciated. About dividing the land. I’m not sure if we will divide or not but if we have to we certainly can. Should be enough road frontage for at least each parcel to have some sort of access. Water is at the road but would have to be run to each home independently. The land is 51 acre in total but we would all like to build on maybe the front 10 acres. Is there any limit on distance for the backup soil sites being that if first one failed we could pump it to secondary site.Any guess how long it would take to have someone come out and do the perk tests? As we are planning on making an offer with closing in 60 days but I think all tgat stuff is supposed to be figured out in more like 50 days. Is this sufficient time. And would it be best if we can be there to at least meet the person doing the testing? Thanks again.

  48. Hello Tim, First of all, Thank you for providing answers for all questions.
    I have High Intensity Soil Map for the land that I am interested in Smyrna. It says Bradyville 0-5% slopes, Fill, some triangles, I.P and Bradyville 75 mpi to 24″, 0-5% slopes.
    What does I.P mean and Fill means? Where does the septic goes and field lines go?

    • I am not sure what “I.P” means. There is no true standard for mapping. You would need to talk to the soil scientist who made the map.
      Fill is land that has had dirt added to it. This is not suitable for a drain field.
      As for where your drain field goes, that will be determined by the Dept. of Environmental Health when you apply for a septic permit (along with the number of bedrooms it can support).

  49. Is pasture land with Dickson soils considered to be percable? In other words, since the fragipan in Dickson soils is generally 30-36″ deep, could the turning of the soil for growing have an adverse effect on soil testing and potential use for a septic system?

  50. Hello and thank you addressing questions. Where can I get a list of soil scientists who do Perc testing in the Roane County/East Tennessee area? Thank you for your assistance?

  51. Hello, seems like your the person to answer this question. So we are looking at purchasing a house and the description says that the site perc’d for a 2bedroom however they put a 4bedroom modular home up on it. Not sure how they got around that but does that mean alternate disposal methods will have to be installed before the home can legally be inhabited again?

    • I had a 3-bedroom modular home installed many moons ago. The local Department of Environmental Health approved it the septic system (the company installing the home sought the permits). It wasn’t until the system began to fail that I found out that only enough drain field line for 2.5 bedrooms was installed. Thing is, the Health Department inspected and approved the install.

      I will have to answer your question with another question. You said the “description says that the site perc’d for a 2bedroom.” Where did you get this information? If it was from the original plat or listing, then it only serves to raise questions. You will need to find the permit that should have been issued for construction of the septic system and preferably, the final inspection. Both of these should be available at the local Dept. of Environmental Health.

  52. Me and my wife are getting 5 acres from my dads farm in bedford co. with plans to build a shop/house (5000 sq/ft)(3 bdrm). We do not have the deed to the land yet, and it has not been surveyed. The surveyors said i needed to contact a soil scientist first. Upon searching for one (with no luck) i came across a guy that does perc tests, and he said i needed a perc test done, then if it fails i need a soil scientist. I don’t want to do something i don’t need to do and was wondering if you could point me in the right direction. Thank you

    • That is bass awkards. You will have to have a soil map. You only need a perc test done if the soils do not have a fast enough absorption rate. You won’t know that until you have a soil map done. The surveyor was right in that you don’t want to cut out a piece of land that cannot support a septic system. That would be a waste of money. Talk to the Dept. of Environmental Health. They should be able to give you contact information for soil scientists that work that area.

  53. We are looking at 7 acres of basically pasture land in Rhea.county which has had perc tests and failed. We just wanted a place to take our camper and have some livestock., but understand that for reals purposes we might need to have information about an alternative septic system. Two questions: do you know what systems are allowed in Rhea County, TN and how we do find out what would be a a fair price to pay for land in Rhea County that doesn’t perk? Thank you

    • When you say “land that doesn’t perc” I assume that there was a place that was tested and failed. The issue is that each perc test only represents a 50-foot square, so unless you had a LOT of perc tests, we cannot definitively state that it “doesn’t perc.”

      That being said, I would talk to a local civil engineer and the health department to see what options you have. I am not familiar enough with Rhea county to know what they do and don’t like.

      As for value. If you truly have a piece of land that cannot support a septic system, you have a piece of land that has very limited use. Anytime you restrict the use of something, the value typically goes down. You would need to talk to an appraiser to have a better idea of what those limits do to the value of the land. In the end, value is what someone is willing to pay.

  54. Hello Timothy, I have 20acres in Marshall county all flat land and is currently being used to plant corn on. I am thinking about subdividing into quarter lots. Is my first step getting the land perc?

    • Your first step should be to talk to a surveyor and have them look over your options. There are many factors beyond septic that controls how you can divide. A good surveyor should be willing to look over the property on paper and discuss your options before you even incur much (if any) of a fee.

  55. Hi Timothy,
    I’m looking to buy an acre lot in Rutherford county. It has an existing 2 bedroom septic on it. How would I find out if it perked for a 3 bedroom?

  56. Hi Timothy, we are looking at purchasing 10 acre lot near Murphreesboro. The property “survey “shows that it perked for 3/2. Does that mean three bedroom two bath? We were hoping to build a three bedroom 2 1/2 bathroom. We’ve only ever seen the perks refer to bedrooms, never bathroom so we weren’t sure what this meant. Thanks in advance for your help.

      • Thank you for all this info! We are under contract for a 21 acre lot in Morgan County. The first 1/3 of the lot is very gently sloping and where we’d like to place our build site. The rest of the lot gradually becomes more mountainous.

        Is a high intensity soil map required before even having a perc test done? The soil scientists all currently have a 5-8 week waiting period. Or could we go straight to the health dept. to schedule a perc test in the area that we wish to build and then do a high intensity soil map only if it fails in that spot?

        I am aware that having the soil mapping done could potentially result in us not even needing a perc test/septic permit, but it is much more expensive (at least $1000) than just having the perc test and septic permit issued by the health department (about $550). We’d like to skip straight to the perc test and permit, if possible. We are fairly confident it will perc. Hope this makes sense. Any guidance is appreciated.

        • As far as I know, you must have a soil map in place. A perc test alone is not adequate. I may be wrong though. It has been a long time since I have had to deal with this element of development. It’s always worth finding out about the permit, you have to do that no matter what.

  57. Hi Timothy,
    Me and my wife just bought 28.8 acres in stewart co and have paid for the perc test and are waiting on the inspector to come do it. The map I have showes a lot of Dickson loam. What does that mean?

    • Dickson silt loam is the soil type. There should also be an absorption rate associated with it. You may also have slopes listed.

      If the slope isn’t bad, then you are simply dealing with the number of feet of drain field for the number of bedrooms. This is determined by the Dept. of Environmental Health.

  58. We are looking at purchasing 7 acres that was auctioned off several years so. It perked for a 3 bedroom modified conventional system at 1.5X. A few questions…

    1. What does the “modified” system mean? Is it significantly more costly than a regular system?
    2. Are there ever times when it would not be approved for the # of bedrooms that it originally perked for?
    3. There are 2 soil sites showing on the plat. Would it be assumed that they both perked for 3 bdrm? One is across a creek from the house site, and wouldn’t want to use that one as we wouldn’t want to run the line across the creek.

    This is all new to me, and I’m trying to gather as much information before making a decision! Thank you.

    • Typically, if there are 2 sites shown, one is the primary system location and the other is 100% reserve. If one or both are modified (cleared, excavated, etc), then your approval is null and void and would likely require new soil mapping. If nothing has changed (short of plant growth), then the map is likely still valid and you should be able to build.

      Remember, both primary and reserve are necessary for the approval of a system. You cannot use one for septic and the other for any other purpose except what it is now.

      As for “modified,” I would guess it will be more expensive. It could be nothing more than a pump tank, or it could be much more extensive with a sand filter and other tertiary treatments.

  59. Timothy,

    I am looking to purchase 5 acres in Cheatham County. The state failed the perc test and told me to get a soil scientist to pass it. I brought the soil scientist to the property and he dug some holes. He told me the soil looks fine and that he would have passed it. At this point we are just waiting for the surveyors to grid map the area and for my soil scientist to come back out. My question here is, can the state come back after my soil scientist passed me, and fail the site?

    Thank you!

    • I suppose the state could, if they send in another soil scientist. If the site failed before, it is because someone probably brought in failed percolation tests or a bad soil map. Also, it may be possible for the soil to have failed because of drains and ditches. There are many factors that go into passing soils for subsurface disposal. However, without a licensed soil scientist or an engineer contradicting your licensed soil scientist, then I doubt they would or could fail the area.

  60. Timothy,

    I’m looking at buying a property and they have already performed a perc test. The build site I want is a little over 200′ away from the soil area. Will I need to get another perc test done closer to where I want to build my house?

    Can you pump your waste that far?

    Thank you,


    • That is an engineering question, but I have seen drain fields be 1000+ feet from the actual septic tank.
      As for perc testing, that is only needed if the soil is poor. You may need to have your soil map amended if they didn’t map the whole lot. But that is if you want to install in a place other than the approved site.

  61. We have some land that my parents have deeded to us, in Maury County. The property has already had a perc test and have documents that state the findings, but it was done almost 8 years ago. Can you tell me if that will still be valid or will another test have to be done. Also, if no other test needs to be done, what would be the next step in starting the building process. Thank you.

  62. If a property for sale has a soil map completed that says the soil is 75mpi at 24 in. 0-5% slope, what are the limitations on the size of house that can be built?

  63. Hi Timothy, we are in the process of purchasing .35 acres of land in Dandridge that doesn’t has a septic system. The property is wooded. Should we have soil map done before we purchase?

  64. Timothy,
    I have several lots in Lake Tansi in Crossville, TN. It has been all septic, but a new sewer plant was built in 2014, but the sewer service has not yet expanded to most of the community. So to build now would require septic. I know that several people that had failed perc tests in Lake Tansi have ended up using a “Wisconsin Mound” above ground septic system to build their houses. I do know the mound systems are more expensive, but
    if I have lots that do not perc for a “regular” in ground septic system, it seems that the lots can still have a house built with an approved Wisconsin Mound” system. Do you see this as a good alternative for a lot that does not perk for a regular in ground septic? I know there are hundreds of thousands of Wisconsin mounds in Florida, for example, why are they not used more in Tennessee?

    • I have never heard of “Wisconsin Mound” systems. It appears to be similar to an LPP system. This is where you use a low-pressure drip field in shallow dirt. I have also seen constructed wetlands (which I would have thought would be very popular in Florida) and multi-stage systems (using gravel then sand filters). The issue with any of these is that they require that an engineer design and sign off on it. This adds to the up-front cost. In any case, it is possible to get this taken care of. If you have an approved lot, you should not be percolation testing them again. I don’t know if the local Department of Environmental Health is grandfathering these lots in or if they are holding them to current standards.

      No matter, if you are in possession of a parcel that cannot support a conventional sub-surface disposal system and you still want to build, you can hire an engineer to design something for you.

  65. I have a 4.4 acres of land in Bradley county, TN. I was looking to build a 5 bedroom home with a pool on it. I have neighbors to the right and back of the property. The builder I hired consulted with a soil scientist and did a percolation test. They said the soil failed the test, and we would need to consult with the dept. of environmental health for alternative septic system, we waited 3 months and today I got a text message from the builder who advised that he has exhausted all options and the only solution was to sell the land and look to a new site for construction. Due to the COVID-19 situation my dept. of environmental health is only accepting online applications and not meeting to answer questions, so I am really short on options. But, researching online I see that there are several options for septic systems out there. What do you think is the best approach to this? I don’t think failing a percolation test should be the end of my dream building this home for my family. Thanks

    • Your best option is to reach out to an engineer in your area that works with alternate systems. In the end, any system that is not a conventional subsurface disposal system will likely have to be designed by an engineer so you ought to start there. You will want to find a localish engineer and call. Tell them the background and see what they say. If one doesn’t think it can be done, call another.

  66. I bought a 4 acre lot in Humphrey’s county west of Dickson. It came with a perc test along with the location of the allowable septic location. I don’t however have a perc rate which I have repeatedly asked for. There are houses in our subdivision already so I do know septics work out there, but since I live in Nevada atm I was wondering what the average requirement for square feet per bedroom are just to have an idea on the septic leach field system. All I am looking for is an or even a guestimate. I hope to start building my home early next year so any help would be great.

    • Honestly, I don’t know the average ft². I know it is 150 gallons per day for the “home” and 100 gallons per day for each bedroom. So a 1 bedroom is 250 gallons per day.
      You would install drainfield pipe along a contour with each line being separated a minimum of 8′ center to center. So, area isn’t as much a concern as linear feet.

  67. My wife and I just purchased 16.75 acres in Carthage, TN and on the survey it says Sykes-Egam 75 mpi to 24 inches WID at 36″ + 0-10% in one area and Mimosa >75 mpi 20-40% in an adjoining area. It also shows an interceptor drain on the survey. I says it will take a 3 bedroom house. Can you give me a little insight as to what that all means? I don’t know if we passed officially or not. Thanks

    • It means that you can get a permit for a 3 bedroom house. You will have to install an interceptor (French Drain). This is a ditch above the drainfield that is typically as deep as the installed lines. You put a perforated pipe (4is inches) in the bottom and cover with #57 ish stone. This is designed to catch both runoff and subsurface water before it infiltrated the drainfield area.

  68. Timothy do you know of any “Non conventional” septic systems that are approved for use in Tennessee on land that won’t perk?, aerobic systems, drip systems etc

    • As far as I know, there are no pre-approved systems. You need to hire a civil engineer to design one for you. I have seen constructed wetlands, sand/gravel filtrations, low-pressure pipes, and several others. But no matter the system, I believe an engineer is required once you move from a conventional subsurface system.

  69. This is a great blog! I learned so much just by reading. Thank you so much for sharing your knowledge.

    Due to COVID both my employer and my husband’s have transitioned to a full-time remote work force. So we have been looking for a 4 bedroom home so we can each have an office plus a guest bedroom. Most of the lots we’ve looked at to build either only perc for 3 or perc for 4 but the soil site takes up half an acre in an undesirable location (front yard) leaving us with a small backyard.

    1. Can we request another perc test in the backyard or is it likely that on the acre lot that was probably tested first and failed.
    2. Since it will just be the two of us living there, do we really need a 4 bedroom perc? In an earlier post you mentioned it may not pass occupancy, but could we say not put a closet in one of the offices thus making it technically not a bedroom and reduce the size of the off limit soil site.

    • I believe that many Departments of Environmental Health also look at the square footage of a house and not only the bedrooms. There have been instances where people will build a 1 bedroom 5 bath house with 4 offices (no closet, no bedroom) and 10,000 ft² because their land didn’t pass for anything more than a 1 bedroom. It really doesn’t matter how many people live in a house, they look at it from its potential use rather than its planned use. It makes sense when you think that most houses will change hands several times over their lifetime and they are there to ensure that it will meet the needs of what the house is capable of.

      Typically, if you don’t like what was laid out, you can have a soil scientist map more of the area, assuming the entire area wasn’t already mapped.

  70. Hi Timothy, love your blog!!! I called the Dept. of Health, Montgomery County (931-648-5747) and pressed #5 – Environmental, I got a recording about it being an open desk, leave message if about pools, food, tattoos. I need to find out if we need a perc test. Do you happen to know the number to call? No-one seems to be able to help at the Health Dept. or the Building and Codes – they don’t know who to contact.

    We have 3 plots under one deed. We have a trailer on plot 1 with septic, we want to build a house on plot 2 (get rid of trailer on plot 1) and will need a septic for plot 2 but not sure if we need a perc test. Where we plan to build is a stone throw from the trailer. Are perc tests per plots or per acre?

  71. We bought a home in 2006 in Lawrence County TN….we were told the lot next to us was unsuitable for field lines and nothing would ever be built there….well 2020 lot was sold and a mobile home and garage were built….state failed the site but soil scientist did a soil intensity test and says it is now suitable….nothing has been done to the property and 13 years of weather and erosion but test shows exact same readings as the soil intensity test he contracted to be done 114 years before when subdivision was being developed…..that lot was held out of the subdivision due to not being suitable for field lines and sold in 2020 unrestricted with a 3 bedroom 2 bath mobile home and a septic system approved for a 2 bedroom 2 bath dwelling…..new owner claims his trailer is a 2 bedroom 2 bath with an office although title to said mobile home indicates 3 bed 2 bath and state approved even after he was caught using creek gravel in his field lines which upon reinspection had already been covered up before reinspection…..can I get a copy of the soil intensity tests done on that property or do I have to seek an attorney?

    • You should be able to go to the health department and possibly get copies of everything (soil map, permit, etc). I am not sure what you intend on doing. If it wasn’t part of the subdivision then it isn’t party to the restrictions, no matter the reason for it not being so. Now, if you can prove that this land was intended on being HOA property or something, maybe you can do something, but as long as they have a permit and a certificate of occupancy, I think they have the right to put whatever zoning will allow but this is a legal question and you should talk to a lawyer about this.

      If by chance, you can show that they fraudulently set a 3-bedroom on a 2-bedroom system, you may be able to try to force them to expand the septic system. I seriously doubt anyone would force the landowner to remove the trailer unless the septic system was failing and could not be repaired. Remember, design is just speculatory. If your house is functioning on it, the health department typically doesn’t do anything about what was installed.

  72. Obtained soil map for 1 acre lake lot in Loudon Co subdivision from records with Knox Co Environment Field Office. Flat then sloping lake lot. Map shows front flat area and some slope mapped, further slope to water unmapped. 1/2 lot mapped. Front of lot DeC Decauter with 5 to 15 % slopes. 45 MPI at 18-30”, 60 MPI at 30-48”. Middle section FuD Fullerton with 15-30% slopes. 45 MPI 18-30” and 60 MPI 30-48”. rear section FuE Fullerton with 30-40% slopes. 60 MPI 18-48”. No hard rock 72” below surface. From what I’ve read above it appears good for septic. Agree? Any limits as to size of home? Planning 3000 sq ft. 4 bed, 3 1/2 bath. Thank you

  73. Hi, there!
    Thanks so much for your help! My husband and I are under contract for a lot in Ooltewah(Hamilton County). We have obtained a high intensity soil map from the surveyors when the subdivision was created. They have approved the lot for a 4 bedroom home, but the field lines/septic area that is approved is in the ideal spot for the home to be built.

    We are trying to decide which way to proceed- what are your thoughts? We have contacted a few local engineers to potentially design an alternate septic system, like an LPP. However, because of the higher cost of this system and the higher potential for failures, we would love to see if the current lines could be relocated and still keep the traditional gravity fed septic.

    Will we need to hire a soil scientist to conduct an extra high intensity soil map?
    At what point would a surveyor come into play?
    And then based on these two findings, we would submit this to the county to repermit the lot?

    Are there other options we have not considered?
    We are out of the country trying to navigate all this in hopes to have a home built to come back to in the next 1.5 years. Any help or advice you can offer would be much appreciated!

    • Yes, you will need to remap the lot to see if there are other areas where a system can go in. Once you have an area that works for you, you take it to the Department of Environmental Health and they can issue a permit for you. Odds are, there wasn’t a permit issued yet anyway. The initial subdivision process requires that there be a usable area shown, but it doesn’t get you a permit.

      Assuming it isn’t “tight” you don’t necessarily need a surveyor, however, I recommend you get one to stake the house where you want it. That way you will know it is square and within setbacks, etc.

  74. We have a contract on a 34 acre property and need to get a perc test completed. The property is in Mountain City, TN. I have contacted Johnson County environmental division. They have pointed me to a state approved list of soil scientists authorized to do the tests. I have contacted a half dozen folks closest from the list and zero response/returned calls/emails etc. Any suggestions? Im in the contingency period right now on the contract so need to get it done in the next few weeks.

    • I am sorry. You could try to check with a local engineering firm, they might have better luck. We don’t do perc tests, but all the surveyors in this area are more than 2 months behind. I talked to a soil scientist the other day and it seems we (Tennessee) are down to 45 working soil scientists for the entire state. That is a VERY low number given the amount of work they have to be experiencing.

  75. Good morning. We are looking at buying property and the seller said the perc site has been registered, and according to the plat the test was done in 2017. The land is in Bedford County. What does a registered perc site mean? Also, the land is on a hillside and we want to build at the top. The perc site is at the bottom of the hill. Will that matter?

    • Registered just means that the perc test was submitted to the health department. This translates into a “permanent” situation. If I submit a failing perc test, a 50′ square of land is now no longer usable for subsurface disposal, for like nearly ever. (over my head what it takes to override it)

      Typically, you want your drain field below the house so you don’t have to pump. Depending on the distance, you may still need a pump, but generally speaking, not pumping is much cheaper than pumping. You need either a second septic tank or a multi-chamber one if you pump.

  76. I do not see my question so I am going to try again. Sorry if for some reason it shows twice. We own a little over an acre in Rutherford County. It is an older home 3 beds and 1 bath. We have been here almost 18 years and it was my husband’s great grandparents home built in the 40’s or 50’s. It is not structurally sound, has electrical issues… it does have a septic that we have never had any problems from. My husband said he was there when his dad put it in (he is 41) and he knows it is a huge tank and the lines are all through the front yard. We would like to tear down this home as we have 4 kid’s and have outgrown the small home and build a 4 bed 2 bath. Will we need a perc test? Would we be able to tie into the existing septic? I think I was told some wrong information as some is not the same as I see stated here. The lady tried to tell me about the septic I had to have not a place for a 2nd system if the first ever failed but to have a 2nd one installed. They also tried to tell me I didn’t have a septic system! Maybe not in their records as it was a long time ago but I am 110% certain we have one lol. They said I need a perc test. I just want the right information! Could we be grandfathered in since there is an existing septic that they say they have 0 records of. I have even ordered the ICC code books to help me understand this better. Until they are here all I have is the internet.

    • One thing to add as I see perc and soil scientist are different. I was told I needed to have a soil scientist come out. So in my initial question when I say perc test I mean soil scientist. Sorry I am learning more as I read all of your questions and answers.

    • Older systems were installed often without permits. So it is entirely possible that there isn’t anything on record for the existing system. Now, it may have been functional for a smaller house, but when you increase the number of bedrooms, you theoretically increase the number of users (and they have to design using the “legal max” number of people in the household – like 2 people per bedroom). So, you would need to expand the drainfield (assuming it wasn’t overdesigned to begin with). When you change something, you have to meet the current regulations. This means that you have to show an area for 100% reserve. This is where, like you said, if your current (new) system ever failed, you could still build a new system. It doesn’t have to be convenient, but it has to be useable.

      My suggestion would be to contact a soil scientist and have them look at your land to see if you can do the expanded system and reserve area. If you could, then file for the permit and run with it.

  77. Do you realize your website was hacked at some point and someone put random links throughout your articles? For example, on this very article, do you see where it says “(Check out korean panax ginseng)” with a link to amazon.

    There are other random links for different stuff throughout other articles. I would reread them all and remove the spam.

  78. Timothy,
    We just purchased 45 acres on the highland rim in Maury. We have a preliminary work up by a TDEC soil scientist, with plenty of locations for sites. My question, however, is how much will certain things alter the sites in question. We have cleared an area via mulching (we were warned no dirt movers) but would like to drag the area a bit/maybe light tilling to plant clover/etc to help keep the brush down. Part of this area appears (on the map from the soil scientist) to be in the 55k ft sq for this ridge’s septic site. Will dragging/tilling seriously mess this area up? We are not planning on building for 4+ years, and current permit expirations are 3 years so I did not want to apply for an official permit or put a system in just yet.
    Also, when you say we have to have room for a reserve system….but not necessarily convenient…does that mean if the second area is 1000ft away, we are still ok? Thanks so much, great thread…us newbies to raw land greatly appreciate it!!

    • To the reserve. Yes, as long as it is feasible to build (but maybe not cost-effective), then you are good.
      As for disturbing the soil, I would like to think that as long as you are not changing anything below a foot deep, you would be ok. However, this will ultimately be up to the soil scientist when they do the high-intensity soil map for the proposed system. If you have had a preliminary review, I would contact that soil scientist and get their take on how deep you can till without affecting the area.

  79. Timothy,
    Thanks for keeping up with all the questions here! Hopefully you have time for another. We have a property in Rutherford County TN that we knew would need an alternative system installed. What we are having trouble with is the steps leading up to the permitting application. The systems we are looking at produce “clean” water at the effluent. In some areas of the country the water can be reused for irrigation and such. It appears here in TN that surface application is not allowed though. The effluent would still need to be run sub surface. We would be using one of the ATS systems that are on the states approved list for Rutherford County. My main question is when using an ATS, do we need a high intensity soil survey done or would we go directly to an engineer to design the system?

    • My guess is that you would need a high-intensity soil map either way. If you know you are going to go alternative, then I would approach an engineer directly. It is likely that they have a soil scientist they work with and may be able to get the ball rolling a bit faster.

  80. My family has a 19 acre lot, we plan to have 2 acres deeded over to me. Its currently vacant cattle farming land.

    Do we need to have it surveyed prior to a perc? I just didnt know if the county would give push back with me being the land owner since Im facilitating things. Also who do I contact to have that done??
    Sumner County TN

    And feedback would be appreciated!

    • My recommendation is to have a soil scientist look it over and tell you where (in relation to where you want to build) you can put your septic system and reserve. Then have the surveyor cut the 2 acres out around that. If the soil scientist tells you that you can pretty much put a septic system anywhere, then do the survey first.
      Either way, you only need a perc test if the soils are getting pretty close to not being able to support a septic system.

  81. Hi there! My husband and I own 2 1 1/2 acre lots side by side in (Millington) Shelby County TN. One lot is our current residence, we are building a new home on the adjacent lot. The builder finally began August 10th 2021. AFter a week of leveling the land; dirt & gravel; we are told “you need to get a Perc test for the septic”. My question is, why isn’t the builder responsible for acquiring a soil scientist? We were never told we would be responsible for this at any point. We are furious because the only soil man near us, Craig Chrestman, is 2 hours away in Adamsville TN and it took a certified letter for him to even respond to me. He stated he did not know when he would be able to come, that was nearly 6 weeks ago. I have called everyone else on the certified list and 99% either do not perform tests anymore or live 4+ hours away. I am frustrated and so upset due to the fact our loan will have to paid back in 6 months and still no house, just a flat pile of dirt and gravel. Do you know of anyone else that works in Shelby County TN? Thanks for your time!!!

    • Unfortunately, I do not know of any soil scientists in that area. Imma go out on a limb here though and say that if you offer enough incentive, you may be able to get someone to get there sooner. But then again, it wouldn’t get me there any quicker.

      Now, I assume that the health department is the one who told you to get the soil scientist involved. I would guess they went to pull permits and found out that the lot was never pre-approved for any kind of system. I would reach out to the Department of Environmental Health and ascertain what is needed and who they recommend. Some of the larger counties have a soil scientist on staff.

      As for liability, I would say you need to read the contract you signed with your contractor. If you have any questions on that, you will need to contact an attorney.

  82. I gave my son and his wife seventeen acres of farmland in Robertson County. I grew fine tobacco on the land for thirty years, and I know a few things about soil. And I know tobacco doesn’t grow on soil with poor internal drainage. My son applied for a septic permit in July, and we destroyed an acre of corn to allow for the inspection. The government guy came out in late August, took two little samples, and said he needed to see more of the land. So we complied by destroying another acre of nice corn. However, he never even showed up until after the crops were harvested. On 10/27/21 he spent a total of twenty minutes on the property, dug one little hole, then messaged my son at work saying he’d have to get a soil scientist. Which means they won’t even break ground until sometime next year.

    Is our inspector in Robertson County just lazy, or is that all a septic inspection is? He had the whole seventeen acres to choose from, with at least three different soil types. All of it is very gently rolling, with no standing water and little if any erosion. If one sample was ‘bad,’ why not take samples somewhere else? My son and his wife started asking different people what to do, and it seems like everybody they have talked to thinks the guy’s an a**.

    I guess my question is: Who do we need to contact to light a fire under the guy? They have sold their house, and they are living in a camper with their little three-year-old daughter with Down Syndrome. He had things arranged to have the house framed and dried-in before winter, but that’s obviously not gonna happen.

    Any advice would be greatly appreciated.

    • I cannot speak to Robertson County, but most do not have a soil scientist on staff. The state law requires a high-intensity soil map to get a septic permit. I would have suggested getting that done first and foremost. I good soil scientist can likely tell you approximately what is useable and what is not without doing much. They will have to take core samples (unless they are very familiar with the land in your area) but shouldn’t be guessing that much.

      I believe each County Department of Environmental Health is stand-alone and answers only to the county. There is a state-level and you can check with them, but I would guess that your best bet is the county mayor.
      You can go to TDEC’s website to find out more about septic systems. https://www.tn.gov/environment/permit-permits/water-permits1/septic-systems-permits/ssp/permit-water-septic-system-construction-permit.html and apparently apply for a permit (this part is new to me).

  83. Hi, I have a 13 acre property in Blount County Tn. Considering selling a portion to my daughter to build on. Haven’t gotten to perc test yet but was told by a neighbor that the lower section of my property does not perc. (Not sure if this is true or not yet). Where I used to live in Mn, a mound style septic would often be installed on land that did not quite meet the perc requirements. Is this a practice that is used in Tn?

  84. Hello!!

    I recently purchased 5.50 acres of land in Christiana (Rutherford County). The previous owner had a soil test done in 2018 that expired this year in September. The map on the test shows that a primary and secondary site were mapped (they are still staked on the land) with each site showing an estimated absorption rate of 75 MPI. The scientist noted this would be approved for a 2 bedroom home.

    After looking at the GIS maps and the soil levels its interesting to me that the primary and secondary sites were done in the very back of the property that has soil type BaC, which seems not great for septic systems. The front of the property, almost 2 acres is LoA soil, which looks ideal for septic systems.

    I have called every soil scientist on the approved document and have been on the books since April to get a perc test done with hopes it would perc for more bedrooms if the land was checked in the LoA soil areas. We had a survey done of the land and he staked areas in the LoA on his soils map.

    We have finalized our house plans and I am not sure how to move forward. Do we wait for the perc test or can we apply for a permit on the TDEC website for the septic system now? We would really like to have something that says we perc’d for more than 2 bedrooms since our current house plan has 3 bedrooms. Any advice/suggestions are welcome! This is our first time purchasing land and building! Thank you!

    • You will need to get a permit. As far as I know, soil maps do not expire (I know perc tests do not). However, if you are wanting to put a system in somewhere that wasn’t mapped, you will likely need to get that area done.
      I am not familiar with Rutherford County but around here, you get your permit from the local Department of Environmental Health. I would try them first to see what they say.

      Also, there may be a reason that the other area was not mapped. It may be that the previous owner planned on future development or didn’t want the system there or a plethora of other reasons.

  85. Wow is all I can say. I read this entire blog, top to bottom. Thank you for sharing your vast knowledge. I had no idea about perc tests before I started researching buying property in Tn 3 years ago. We had hoped to buy 100 acers in E. TN and put cabins but it seems that a lot of people got the same memo and now land has tripled. Crazy times. I hope this doesn’t offend but the soil scientist and perc testing seems a bit contrived. I am admittedly very uneducated in this field but it just strikes me as odd that you could have a perc test done, when the ground is wet. Not get the results you want and not that 50 ft square piece of land is permanently unusable when it may be very possible to change the reading if under drier conditions. Also, why can’t you amend the soil in some kind of way to improve the absorption? Does the drain field take only black water or does it include grey water like showers and sinks, and if so, why can’t those be used for irrigation? I am starting to get the feeling that this is going to be a struggle when we do buy land in a couple of years but I hope things (and prices) settle down. Is it possible that an engineer might approve a design I made if deemed acceptable or do they have to design it, and charge for the honor? Thanks in advance for all my random questions.

    • My guess, and this is only a guess, is that while you may design a system, an engineer would need to do all the maths and whatnot before they would sign it. As for the testing when wet, well, that is a real-world issue, isn’t it? I mean, if the ground can become saturated and not capable of absorbing the effluent, then it should not pass. As for blackwater or greywater. All goes into the tank and all goes into the drain field as a single product. I can say I have seen a lot of areas where people have not dumped their greywater into their septic tank. I knew one person that the only thing going into the septic tank was the toilets and the kitchen sink (the latter for the greases and food particles) and the remaining wastewater ran through a 150′ gravel filter lined with river birch. Unless it was a rainy day, the water never made it to the end of the gravel and out to the natural drain. In fact, this was painfully evident as the first river birch was much larger than the last. Obviously not getting the same amount of water.

      There are a lot of things that can be done, but if they don’t fit into the neat little boxes that the state has, then you will have to have an engineer sign off on them.

  86. Hi Tim,

    We just purchased land on Cherokee Lake in Bean Station TN. We have applied for a perc test, but found out yesterday that its going to take up to 6 weeks to have this done. My question to you is can our contactor break ground to start building out 50×50 workshop with a one bedroom apartment attached to it before the perc test is done? Any suggestion would be great! Nancy

    • There are two issues with starting early. First and foremost, you may inadvertently damage an area of land that could have been used for your drainfield. However, if the contractor limits the excavation (and piling dirt, etc) to within a very short distance of where you need the garage to go, I don’t see any issue there. The next is are you fine with the garage without an apartment if you cannot get a permit for the septic?

  87. My mom has 7.6 unrestricted acres in Warren County. She has a 3 bedroom home with septic that was built about 12 years ago on the front 1/3 of the property. My husband and I are wanting to build a home somewhere on the middle 1/3. Her home is a manufactured home, ours would be too. The dealer says people do this all the time building on family land or rented land. Warren county does not require building permits or installation inspection for manufactured homes, but obviously the state regulate septic systems so we would need a permit for putting in a second system. Since she had it perc tested and then modified the land by building her home does this mean we need to have another perc test to find a site for a second system? Can we place a second home on 7.6 acres? There are several neighbors with various structures, but not sure all of them are “legal”.

    • You just need to go to the Department of Environmental Health for Warren County and see what she had done. It is probable that she only had the area she used mapped. If that is the case, you too would have to have an area mapped. This will require a Soil Scientist.

  88. Hello! This blog is incredibly insightful and thank you for taking time to respond. I’m sure you’ve provided invaluable help to everyone here. Had a couple of questions. We’ve recently purchased a ~9ac property in the Mt Juliet area. There is an “ancient” perc test on file from 1985 which permitted a 1 bdr dwelling at the time. It’s quite a large lot as where all adjacent neighbors (quite close to the property lines on two sides) have built some very large homes (including a 12k sq foot castle of a home just next door). Understanding things certainly could vary from property to property, I would have to think the general soils profile wouldn’t be so different from their lot which is maybe 300ft away where a much large home was recently constructed, that there wouldn’t be percable soil found within the lot. Given the original test was so long ago (36 years) and as I understand was done to accommodate a mobile home at that time, is there a reasonable chance that the city would review a newer soils test (or perhaps allow us to ammend/appeal the original testing submittal)?

    • You are stating that there is an existing permit, not perc test. It is quite common to redo a soil permit to get more bedrooms. It is likely that they simply got what was needed for the proposed structure and didn’t look any further. The only way to know is to contact the Dept. of Environmental Health and file for an amended permit (or given the age, a new one).

  89. I am looking at 11.43 acres. It had a septic permit for a 5 bedroom house. Is it possible to put 2 2 bedroom houses on that land?

  90. I’m looking at a property on a zone AE flood plain along the Tn. River. It adjoins TVA fee property along the river with no flowage easement on the property I’m looking at. Is there anything special about installing a septic system in a flood plain that I need to be aware of. Thanks for your time.

  91. Does the “perc” refer to number of bedrooms allowed, or number of bathrooms allowed? I always thought it was number of bedrooms, but a friend of mine recently told me it was bathrooms, so now I’m curious because we’re looking at adding onto our property and need to know if we need an additional perc site or if we can just use our current one.

    • Standard house occupancy is determined as 2 people per bedroom. It doesn’t matter if you have 3 bedrooms and 6 bathrooms, the notion is that each person (standard occupancy) will utilize the same amount of water, no matter how many bathrooms you have. In Tennessee, the volume for calculating the needed linear feet of drain field line is based on 150 gallons per day for the 1st bedroom and 100 gallons per day additional for each added bedroom. It is then compared to the absorption rate of the soil that the lines are laid in. This is what a perc test is used to ascertain.

      It is worth noting that they (the Dept. of Environmental Health) get a bit suspicious when someone proposed a 50,000 ft² house with only two bedrooms.

      So to answer your question, adding bedrooms, not bathrooms, requires increasing the drain field size.

  92. This blog is an education in itself.
    We have had a soil map done on a lake lot in E TN and have been told that it is Capshaw and will not perc. Next step is an alternative system.
    The soil engineer who did the soil map knows nothing about aerobic systems. Do I need to talk to other soil engineers, a civil engineer or the TDEC guys? Thank you.

    • I believe that if it is not a subsurface disposal system, you have to have it designed by an engineer. So, I suggest contacting your local civil engineers to see if they do anything like it. There are many options, but it will all depend on what your person is willing to design. You may get a jump start on that by contacting the local Environmental Health department to see if they know of any engineers in your area that do these sorts of systems.

  93. Hi Timothy! I am buying 8 unrestricted acres, West Moreland TN, so they tell me I don’t need a “perc” test, just a septic permit. So 2 questions, can a septic permit fail? Also I know im not supposed to disturb the land but can I dig to plant trees before having the permit process done?

    • A “permit” won’t fail. It can be nullified by ground disturbance, but it won’t fail. If you don’t need perc tests it likely means your soil type is good enough not to require verification. As for trees, I don’t know. I would assume you do not want to plant trees where the system would be installed. There are also some trees that you would not want anywhere near a septic system, like willows.

  94. We own over 30 acres in Roane County. We had to start excavating prior to getting a septic permit in order to determine where we are even going to have the best building site. The property was logged several years ago and was a mess.

    I now have a soil map from a soil scientist from the approved list and the inspector came out and denied the area that was mapped and is saying I have to put the system in a very difficult location that will require a complicated pump system. If I get a perc test in the preferred area and it meets the specs can he still deny that location? I really don’t want a pump system!

    • If your site has a valid soil map of the area you want to install, I would assume you could “appeal” the local decision through the State. Look to TDEC to see if they have a process like this. But before you do, you will need to ensure that the soil map is up to date, post-excavation.

  95. Hello Tim. I am in need of a soil/Perk test done on a lot located at 157 Big Cove Creek rd. Roan Mountain TN it is the lot across the street, for my 2 bedroom 2 bath home which is to be delivered first week of August. Please let me know how much the test is and how soon your availability will be?
    I appreciate your time and response. I understand it’s a busy time.
    Thank you so much!

  96. My wife and I have found a nice plot of land on which we would like to build our retirement home. There are several mature trees and I see no areas that look as if it has been disturbed for dumping etc. We have been able to find someone to do perc but cannot find a soil engineer to qualify the soil content as buildable. Is this necessary in west TN or is it assumed the land is buildable / If a soil engineer is recommended do you know someone? Our planning dept only knew an individual to do the perc testing. Thank you

    • I cannot speak to the area as we are in East Tennessee, but if you are concerned, search for a local Civil Engineering firm and they should be able to direct you to someone who does what you are looking for. It is very common around here that the contractor “decides” if the land is structurally sound. I am not saying if this is good or bad, but it is how things are basically done.

  97. I have a simple question, if your land doesn’t perc, why cant you bring in good soil that will perc and let it settle in for awhile. I had 5 acres but it was a lot of clay and wouldn’t perc. I only had about 8″ of good soil before you hit clay and 20″ was needed before you can put in a mound system. Why couldn’t I just build up and area? They said you can bring soil in…it has to be original and undisturbed.

    • Honestly, I don’t know. There are many other options. Contact an engineer and see if they can do something like a constructed wetlands or an LPP system.

  98. Bought a new constructed home in Washington cty tn, subdivision, on half acre lot. After 6 months water backed up – we have a 75 mpi. The lines were drained, drainline for gutters moved, and 2 overflow tanks added. This over flow tanks were drained 3 weeks ago again. Today we were supposed to have had the lawn done but hit water. They decided to cap a line running to the overflow and when they dug water filled the hole and took several hours to drain , a few hrs later water is back in. The state is coning out tomorrow. Any suggestions from you ? Everyone seems baffled of where the water is coming from. Its a 3 bedroom home but just my husband and i – bill is only about 35-40 dollars. So not much water is used.

    • Not sure. In a situation I had in my own house, I had a drain field that consistently stayed wet. We found that the runoff from the uphill neighbor was saturating the system. Once I installed an interceptor ditch, I could dry out the field. I am not, however, sure how in the world your tanks are filling unless it is backfilling from the drain field. That, or there is a neighbor tied into the same system. It wouldn’t be the first time that’s happened.

  99. Our land was mined for phosphorus decades ago. We recently had a soil scientist come out. He dug a few holes and said he didn’t think the land was buildable. He wants to come back with a mini excavator and dig deeper. He did not test absorption at all, just simply observed the soil. Is it possible to deem land not suitable for septic without performing an absorption test?

    • This is a difficult one. It may be? Depends? Honestly, if the surface has been disturbed, then it may not be suitable for subsurface disposal. You may need to hire a structural engineer to ascertain the usability of the land.

  100. I have a property that was soil mapped in 1997 a significant portion was labeled “not mapped not classified disturbed” Can I now have this portion mapped and classified?

  101. Hi, I just bought a land in Wilco which is about 2.5acrs. It is H-Hamlet zoning. I did a soil test and in results it says “ The soil was identified as the Stiversville/Nesbitt series with an estimated absorption rate of 75 minutes per inch”
    My question is – is there a minimum or Maximum MPI boundaries for a commercial structure in Hamlet zones?

    • This is entirely a zoning question. Most municipalities have their zoning ordinances posted online. You can usually check those to identify the permissible uses. If not, the next step is to contact either zoning or codes enforcement (depending on what office your municipality has).

  102. We are purchasing land in Roane Co., it is undeveloped farmland. There has been a soil mapping done on the property but not a PERC test. Is one still needed and who does those?TIA

    • Percolation tests are only needed in areas where the soil type is poor enough that it has to be “proved” to be usable. If you haven’t been told so, you likely do not need any perc tests.

  103. We are looking at buying a property in Polk County, and it had a perc test done in one area on the 10 Acres we’re looking at purchasing, someone had mentioned that I might need a second one done, to show that we have a secondary site for a septic in the event we need to replace the original, is this something that is required? I cannot seem to find anything saying I do need one, and our realtor is also looking into this but hasn’t gotten back to us yet.

    • Typically, you have to show 100% reserve. It doesn’t necessarily need to be a separate area. If the site you have set already is large enough, this may meet that requirement.

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