Fifty feet, from the tank and from the drainfield. This page has the full state table, the reason you keep reading "100 feet" online, and what to do when an older Maury County well sits closer than that.
A well has to be at least 50 feet from a septic tank in Tennessee, and the same 50 feet applies to a pump tank and to the drainfield. Two state rules agree on that number: the septic rule (0400-48-01-.11) and the well-construction rule (0400-45-09-.10). Measure from the well to the nearest edge of the tank or field.
The septic rule governs when a system goes in near a well. The well rule (Table A) governs when a well gets drilled near a system. Where they overlap, they match, so you get one answer either way.
| From the well to | Minimum distance | Where the number comes from |
|---|---|---|
| Septic tank | 50 feet | Septic rule and well rule |
| Pump (dosing) tank or aerobic treatment unit (ATU) | 50 feet | Septic rule |
| Drainfield, which the rule calls the disposal field | 50 feet | Septic rule and well rule |
| Sewer line | 50 feet | Well rule; tight house connections have a separate 10-foot provision |
| Watertight house-to-tank or house-to-sewer connection | 10 feet | Well rule; the connection must be tight |
| Outhouse | 75 feet for a new well (the septic rule says 50, so use 75) | Well rule |
| Animal pen or feedlot | 100 feet | Well rule |
| Sludge or septage disposal site | 100 feet | Well rule |
| Leaching pit or sewage lagoon | 200 feet | Well rule |
These are floors. The septic rule says they apply "bearing in mind that local conditions may require increased distances of separation," and your issued TDEC permit and site sketch show what was approved for your lot. The same septic table also keeps tanks and fields 10 feet from water lines.
Read the rule text: Rule 0400-48-01 (septic) · Rule 0400-45-09 (well construction)
In Tennessee it's 50. The "50 feet from the tank, 100 feet from the drainfield" line that turns up in national articles is a real rule, but it belongs to states like Texas. Alabama uses 100 feet for both. If you read a number online, check which state wrote it.
Those states give the field the bigger buffer for a reason worth borrowing. A tank is a sealed box. A drainfield is built to let effluent (the liquid leaving the tank) soak into the ground. When you have room, greater separation may add protection, but the driller must also consider groundwater flow, well construction, access, and cost.
| State | Well to tank | Well to drainfield | Source |
|---|---|---|---|
| Tennessee | 50 feet | 50 feet | Rules 0400-48-01-.11 and 0400-45-09-.10 |
| Texas | 50 feet | 100 feet | Texas Department of Licensing and Regulation well-driller guidance |
| Alabama | 100 feet | 100 feet | Alabama Water Well Standards, as summarized by Alabama Cooperative Extension |
Other states appear only for comparison. On a Tennessee property, Tennessee's rules and your TDEC permit control.
Comparison sources: Texas TDLR separation distances · Alabama Extension well placement
Under much of Maury County, limestone is fractured, so water leaving a drainfield can follow a crack toward a well faster than the 50 feet on the tape suggests. These are the things on a lot that should push the well farther away.
| What you see | Why it matters for the well | What to do |
|---|---|---|
| A sinkhole or closed depression | Surface water and effluent can drain straight into it | Map it. The septic rule keeps drainfields 25 feet and tanks 15 feet from sinkholes, and a soil consultant's special investigation can change them |
| Well downhill from the field | Water on top of and under the ground tends to run toward it | Put the well uphill when you get to choose |
| Low ground that floods | Floodwater can reach the wellhead and soak the field at the same time | A new well in a flood area needs its casing at least 2 feet above the 100-year flood level; test after any flood |
| An old or cracked casing | A bad seal lets surface water in at any distance | Have a licensed well contractor inspect and repair it |
| A neighbor's septic near the line | The closest septic system may not be yours | Show nearby wells and systems on the site plan |
Rule 0400-45-09-.10 also covers how the well itself is built. These are the parts that matter most on a septic property.
Watertight casing runs from at least 19 feet below ground to at least 6 inches above it, sealed around the outside with grout or bentonite from 3 to 10 feet down. The water source itself has to be at least 19 feet below the surface.
A well closer than 50 feet to a septic tank, field line, or sewer can't be fractured to improve its yield. That rules out an easy fix for a weak old well sitting near a system.
New wells sit at least 10 feet from a property line. Between 10 and 25 feet, the well needs at least 35 feet of grouted casing.
A well can go in an area that floods only when the top of the casing is at least 2 feet above the 100-year flood level.
Plenty of older Maury County houses have a well and tank closer together than today's table allows. Test the water before anyone digs. A clean result from a deep well with a sound casing is a different situation from a positive bacteria result on a shallow well with a cracked cap.
Next, pull the paper. The TDEC septic permit may show the system predates the current rule, or that the old sketch was a rough guess. The well report shows the depth and casing. With both in hand, ask TDEC's Columbia office what applies if you keep using the system, repair it, or sell. Tearing out a working system on a hunch can ruin the only good soil on the lot.
Order a certified lab test. If the result or the site worries you, follow the lab's and the health department's advice on drinking the water while you sort it out.
The TDEC septic permit and any repairs, plus the well report with its date, depth, and casing.
Have the tank, field, and well found and measured. Old sketches are often off by more than the setback.
That could mean resealing the well, repairing or moving the field, drilling a new well farther off, or treating the water while the source gets fixed.
On a bare lot, the driller, the house designer, and the soil consultant each tend to grab whatever corner looks open. Put all of it on one drawing first. Tennessee requires a full duplicate area, a reserved spot for a replacement field, and the well needs its 50 feet from that area too. A well drilled 55 feet from today's field and 30 feet from the reserve area can block the lot's only backup.
Plan the trucks as well. A pump truck needs a path to the tank, and a well rig may need to come back someday. Neither route should cross a field, since Tennessee bans driving and parking on the disposal field.
About our sources. Maury Septic uses the sources listed below, including Tennessee's well and septic setback rules and private-well testing. Follow the links for the underlying rules, fees, and guidance.
Tennessee Secretary of State
Official current chapter text governing Tennessee subsurface sewage disposal systems.
Tennessee Department of Environment and Conservation
Current state policy for digital permit sketches, attachments, reproducible field references, setbacks, and FileNet record quality.
Tennessee Department of Environment and Conservation
What an approved consultant evaluates, current qualification rules, and the state consultant list.
Tennessee Department of Health
State instructions encouraging annual bacteriological testing and additional testing after flooding, disasters, or suspected contamination.
Tennessee Department of Health
Private-well maintenance, certified laboratory testing, contaminant selection, sampling, and owner responsibilities in Tennessee.
Tennessee Geological Survey
State-published geologic, unstable-materials, flood-prone-area, mineral-resource, and sinkhole maps for Maury County.
U.S. Environmental Protection Agency
Technical explanation of rapid recharge, conduit flow, precipitation response, springs, and contaminant transport in karst aquifers.
Tennessee Department of Environment and Conservation
Official state viewer for locating septic-system permits, site sketches, and related records.
It does. Tennessee requires a full duplicate area for a future replacement field, and that area has to meet the same setbacks as the field in use. A well that clears today's field but sits close to the reserve area can leave the lot with nowhere legal to put a replacement.
The table measures from a water supply to septic parts and doesn't carve out a neighbor's system. When you plan a well or a septic system near a property line, show the neighbors' wells and septic systems on the site plan so the reviewer can see them.
That the water needs prompt follow-up, though it doesn't prove the septic system is to blame. Follow the lab's drinking-water instructions and retest to confirm. Then check the well cap and casing, surface runoff, plumbing, and animals along with the septic system before you pick a fix.
Don't count on it either way. Get the install dates, the TDEC permit, the well report, the measured locations, and a water test, then ask TDEC's Columbia office what applies to continued use, a repair, or a sale. The records and the water result decide it.
Moving the well is sometimes the cheaper fix. A new well needs 50 feet from the tank and both field areas, a spot a drill rig can reach, decent yield, and proper sealing of the old well. Find out what is actually causing the problem before choosing which one moves.
Describe the lot, roughly how far apart the well and septic sit, and any permit or water results you have. We'll look for a licensed Maury County installer who takes that kind of job and pass your details along. We don't test water or approve setbacks.
Related: all Tennessee septic setbacks · sinkholes and karst · soil and site evaluation · TDEC records lookup · buying a home with septic · TDEC Columbia field office · building over a drainfield
Keep your permit, system sketch, and service records together. They help the next professional understand your property.