Nationally, a perc test runs about $750 to $1,900, with an average near $1,300 and roughly $150 per hole. That is the number every cost guide gives you, and around Memphis it is the least useful thing you can know.
Here is what actually determines how this goes: in Tennessee, the perc test is not the first step, and in Shelby County the state does not handle your application at all. A soil evaluation by an approved soil consultant comes first, and the percolation test only happens if your soils qualify for one. Plenty of lots never get a perc test, because the soil map already answered the question.
That changes who you call, what you pay for, and in what order. Here is how a septic site evaluation actually works in Shelby, Tipton and Fayette County, and the one phone call that decides the rest of it.
Tennessee Starts With a Soil Map, Not a Hole Full of Water
Search this topic and you will get the classic description: dig holes, pre-soak them, fill them with water, time how fast the level drops, get a rate in minutes per inch. That is a real procedure and Tennessee does use it. It is just not where the process starts.
Under the state's rules, a general or high intensity soil evaluation is conducted by an approved soil consultant first. Only after the soils are examined and found to have the listed characteristics does the rule say a percolation test may be conducted. The state's own Soils Handbook puts it plainly: the only purpose of those soil maps is to determine whether the soils on a site meet the requirements to be evaluated by using percolation tests in the first place.
And the perc result does not get the final word even when there is one. The rules state that percolation test results shall not be conclusive evidence as to the suitability of an area. They are one of many criteria.
This is the part that trips people up when they have read a guide written for another state. If you call around asking for a perc test and nobody will schedule one until a soil consultant has looked at the lot, nothing has gone wrong. That is the sequence.
Who Takes Your Application Depends on Which County You Are In
This is the detail that sends Memphis-area landowners to the wrong office, and no national cost guide mentions it.
Tennessee's Department of Environment and Conservation runs septic permitting for most of the state through its Division of Water Resources, with an online application. But a handful of counties provide ground water protection services for their own areas, and TDEC's application page states that the online form is not to be submitted for services requested in them. The list is Blount, Davidson/Nashville, Hamilton, Jefferson, Knox, Madison, Sevier, Shelby and Williamson.
So within one service area, there are two different front doors.
Shelby County: the county handles it
Anyone requesting the installation, modification, repair or abandonment of a subsurface sewage disposal system in Shelby County submits an application to the county's Water Quality Branch and Septic Tank Program. A non-refundable processing fee of $175 goes in with the plot plan and the soil analysis, for each system.
The county reviews the application for completeness before arranging a site visit to site the septic tank. An incomplete application does not get a site inspection until the missing information shows up, which is the most common reason these stall. The county's stated time frame for issuing a permit is one to two weeks after a complete application has been received, and a site inspection is done during installation to confirm the tank goes in according to the regulations.
Worth knowing if you are dealing with a system that already exists: repair work requires its own permit, and the county will not issue one until a site inspection has verified that the repair meets siting criteria.
Tipton, Fayette and the rest: the state handles it
Tipton and Fayette County are not on TDEC's carve-out list, so they go through the state. The application is filed with the Division of Water Resources, and the state's online application covers four permit types: Conventional Septic System Permit, Alternative Septic System Permit, Septic System Repair Permit and Septic System Modification Permit. Questions go to your local Environmental Field Office.
A practical note on fees: the state's septic permit pages do not publish a fee schedule, and we are not going to invent one for you. Call the Environmental Field Office and ask what the current fee is for the permit type you need. The $175 figure above is Shelby County's, and it applies in Shelby County only.
If your property sits near a county line, settle this before you pay anybody for anything. A soil consultant's report written for the wrong submission process is a real way to spend money twice.
Some Soils Never Get a Perc Test at All
The soil evaluation can rule a site out before a single hole is dug. Under the state's rules, soils are excluded from percolation testing for conditions including:
- Fragipan properties, a dense restrictive layer that water moves through slowly
- Aquic, glossic, fragic and vertic subgroups
- Insufficient depth to rock: under 36 inches in karst areas, under 30 inches elsewhere
- Slopes over 30 percent, absent a special investigation
- Various wetness and flooding conditions
That first one deserves attention around here. Three of the soil series mapped in Tennessee, Loring, Grenada and Calloway, carry a fragipan formed in loess, with slow to moderately slow permeability within that layer. The Loring series reference profile is located in Shelby County, Tennessee, and its fragipan sits anywhere from 14 to 35 inches down.
Put that next to the testing rules and the picture gets clear. A percolation test hole has to reach a minimum depth of 26 inches in undisturbed soil. On a Loring profile with a fragipan at 14 inches, the hole is being cut straight into the restrictive layer, which is exactly the condition the rule excludes from perc testing to begin with.
This is why a soil evaluation is money better spent than a perc test on a lot nobody has looked at yet. It can tell you the answer is no before you pay to prove it slowly.
What the Test Itself Involves
When soils do qualify, the state specifies the procedure rather than leaving it to the person running it:
| Element | What the rules require |
|---|---|
| Hole size | Dug or bored, 6 to 12 inches across |
| Hole depth | Minimum 26 inches of undisturbed soil, for all system types |
| Preparation | Two inches of coarse sand or fine gravel in the bottom |
| Pre-soak | Clear water to a minimum of 12 inches over the gravel, kept in the holes overnight |
| Timing | Measurement begins 24 to 30 hours after the holes are first filled, with the drop read over a 30 minute period |
| Additives | None permitted |
| Notice | The Department is notified at least three days before the test day |
Two things fall out of that table. First, this is not a one afternoon job. Water sits in the holes overnight and the reading happens the following day, so between the three day notice and the overnight soak you are looking at the better part of a week from scheduling to result. Second, it is not a do-it-yourself item. Soil maps, soil evaluations and site investigations are submitted by professional soil scientists licensed through the Tennessee Department of Commerce and Insurance and separately approved by the Division of Water Resources, which maintains a list of licensed soils consultants. That approval is on top of the state license: the qualifying route includes a soil science or agronomy degree, two years of soil evaluation experience, and a three phase examination that covers a written test, a field mapping test and review of a consultant's first five high intensity soil maps.
You are not hiring someone to dig a hole. You are hiring someone whose signature the state will accept.
Get the Permit Before You Move Any Dirt
TDEC's guidance is specific and it is the single cheapest thing in this article to act on: a permit should always be obtained before starting dirt work or construction of any building, including the building pad.
That sentence is doing more work than it looks like. The septic field needs a specific area of undisturbed soil, and undisturbed is the operative word. Cut a building pad across the part of the lot the field was going to use, or track equipment over it in wet weather, and you can compact your way out of a system the soil would otherwise have supported. We have seen the order of operations cost people more than the system did.
It also sets the sequence for everything else on a raw lot. Land clearing, the driveway culvert, grading and the water line all want to be planned around the approved field location, not discovered to be sitting on top of it.
There is a lot size floor too. In the perc testing rules, the minimum is 20,000 square feet where a public water supply is used and 25,000 square feet with a private water supply. Roughly half an acre and a little over half an acre, respectively.
If the Site Will Not Support a Conventional System
A failed or disqualified site is not automatically an unbuildable one. Alternative systems exist for exactly this, and the state issues an Alternative Septic System Permit for them, typically used when soil or site conditions are not favorable for a conventional system.
The requirement to know about before you get hopeful: an extra-high intensity soils map must be submitted to the Division before staff can evaluate any property for an alternative septic system, and that level of map is required for all alternative methods of sewage disposal. Where perc holes are used for an alternative system, they go in on a grid with maximum perpendicular distances of 25 feet, which means more holes than a conventional evaluation.
So the alternative path starts with more soil work, not less. Budget for the mapping before you budget for the system, and ask your soil consultant what an extra-high intensity map costs on your acreage before you commit to the lot.
What We Do, and What We Do Not
We will be straight about the division of labor, because it is the thing people are most often confused about when they call us.
Modern Shovel does not perform your soil evaluation or your perc test. That is a licensed soil consultant's work, their signature, and their report. Anyone in our trade who offers to perc your lot themselves is either subcontracting it or telling you something that is not going to hold up with the permitting office.
What we do is everything after: septic system installation, tank and field lines installed to your permit, full replacements, and field line replacements on systems that have failed. We are based in Millington, owned by Austin Scott, fully insured, and we hold a 4.9-star rating across 30+ Google reviews. Because we already handle the clearing, grading and culvert work on a lot, the septic install fits into the same site work instead of waiting on another contractor's calendar.
And we will tell you which office handles your permit for your county, which as of this writing is the question most people arrive with. That part is free.
Call (901) 479-0236 or request a free estimate. We cover Millington, Memphis, Bartlett, Arlington, Lakeland, Atoka, Munford, Brighton and Covington, and out through Tipton and Fayette County. See the full service area.
Frequently Asked Questions
How much does a perc test cost in Tennessee?
There is no published statewide figure, and the soil consultant's fee is set privately, so get a quote on your specific acreage. For national context, Angi reports a 2026 average around $1,300 with a typical range of $750 to $1,900 and roughly $150 per hole. The one firm local number is Shelby County's $175 non-refundable processing fee, which is the permit application fee and not the cost of the evaluation itself.
Who performs a perc test in Tennessee?
Not your excavation contractor. Soil maps, soil evaluations and site investigations are submitted by professional soil scientists licensed through the Tennessee Department of Commerce and Insurance and approved by the Division of Water Resources, which keeps a list of licensed soils consultants. That approval requires a relevant degree, two years of soil evaluation experience and a three phase examination on top of the state license.
Do I apply to the state or the county for a septic permit?
It depends on your county. TDEC's online application specifically excludes nine counties that run their own ground water protection services, and Shelby is one of them, so a Shelby County application goes to the county's Water Quality Branch and Septic Tank Program. Tipton and Fayette County are not excluded, so those go through the state's Division of Water Resources and your local Environmental Field Office.
What happens if my land fails a perc test?
An alternative system may still work, and the state issues an Alternative Septic System Permit for sites where soil or site conditions are not favorable for a conventional system. The catch is that an extra-high intensity soils map has to be submitted before Division staff can evaluate the property for one, so the alternative route begins with more soil mapping, not less.
How long does a perc test take?
Longer than a day. The Department has to be notified at least three days before the test, water sits in the holes overnight, and the measurement period does not begin until 24 to 30 hours after the holes are first filled, with the drop read over 30 minutes. Plan on the better part of a week from scheduling to a result, and do that before you need the answer.
Got Your Permit? We'll Install It.
Tank and field lines installed to your permit across Millington, Tipton County, Fayette County and north Shelby County. Not there yet? Call and we'll tell you which office handles your county. (901) 479-0236
Sources: Tennessee Department of Environment and Conservation, Division of Water Resources, Online Application for Ground Water Protection Services and Subsurface Sewage Disposal System Permits pages; TDEC Soils Handbook of Tennessee (DWR-SSD-G-01), including Rule 0400-48-01-.03(b) and the approved soil consultant requirements at 0400-48-01-.18; Shelby County, TN Subsurface Sewage Disposal System FAQ, Water Quality Branch and Septic Tank Program; USDA Official Series Descriptions for the LORING, GRENADA and CALLOWAY series; Angi, perc test cost data, updated September 2026. Fees, rules and county responsibilities change. Confirm current requirements with the issuing office before you spend money or move dirt.
