The acreage on a listing is not the space available for a house, water supply, initial disposal field, and protected replacement area.
Current TDEC permit standards show 50 feet from tanks and fields to a water supply, 10 feet from fields to dwellings and property lines, and 25 feet from fields to sinkholes, streams, drainageways, ravines, or cut banks. The site sketch also identifies a 100 percent duplicate disposal area. Soil and site review can change some distances.
These are the separation distances set by TN Rule 0400-48-01-.11, reprinted in TDEC's July 2024 permit-documentation policy. The soil investigation and issued permit control a specific property.
| Feature | Tank, dosing tank, or ATS | Disposal field | How to use the number |
|---|---|---|---|
| Water supply | 50 ft | 50 ft | Includes the drinking-water source shown on the permit sketch |
| Dwelling | 5 ft | 10 ft | Measure to the permitted structure location |
| Property line | 10 ft | 10 ft | A survey may be needed when the boundary is uncertain |
| Easement boundary | 10 ft | 10 ft | The easement itself can remove more usable area |
| Gully, ravine, dry stream bed, natural drainageway, sinkhole, stream, or cut bank | 15 ft | 25 ft | May change after a special investigation by an approved soil consultant |
| Water line | 10 ft | 10 ft | Show known and proposed lines on the site plan |
| House-to-tank connection | Not listed | 10 ft | This row protects the disposal field from the building sewer |
| Septic or dosing tank | Not listed | 5 ft | Separation shown between a tank and disposal field |
One caveat is built into the rule itself: the distances for gullies, ravines, dry stream beds, drainageways, sinkholes, streams, and cut banks may increase or decrease when soil conditions warrant, as determined by the Commissioner after a special investigation by an approved soil consultant. So none of the eight rows is unconditional on its own; the drainage-feature row in particular can move after a soil investigation.
Start with a reliable survey; the fence line and the tax-map screen both lie. Mark access, utility, drainage, and shared-drive easements because boundaries and restricted corridors remove possible system space.
Show the house, porches, garage, driveway, water supply, water lines, pools, barns, utilities, and other construction. A future feature can be as important as one already on the ground.
The soil consultant identifies usable soil and site limits. Steep areas, shallow rock, wet positions, fill, disturbed soil, drainageways, and sinkhole terrain can remove acreage that looks open on an aerial image.
TDEC applies the design flow, soil interpretation, system type, setbacks, tanks, piping, and field configuration. The required shape is not simply a rectangle copied from a neighboring permit.
Every permit sketch reserves a 100 percent duplication area, a full second field for the day the first one wears out. Keep that envelope reproducible in the field and free from grading, structures, and traffic.
The five-acre provision is real, but it says something narrower than the folklore. Rule 0400-48-01-.02 defines a subdivision to exclude divisions where every resulting tract is five acres or larger, and TDEC's online service guidance repeats it. That is a subdivision-evaluation threshold. It is not a soil approval, a construction permit, or a guarantee that a five-acre homesite supports septic.
A five-acre parcel can be mostly shallow rock, wet landscape, severe slope, easement, flood-prone ground, or karst drainage. A smaller parcel can sometimes fit an approved layout when it has suitable soil in the right place. The decisive question is how much compliant soil remains after the house, water supply, setbacks, initial field, and duplicate field all fit together.
If land is being divided, use TDEC's current subdivision-evaluation guidance and local planning rules. The five-acre statement does not remove deed restrictions, road-access requirements, zoning, survey work, or the construction permit for each proposed system.
The Tennessee Geological Survey's Maury County atlas maps sinkholes, unstable materials, flood-prone areas, and varied rock units. A sinkhole is not always a neat circular hole. The relevant site feature can include a broad closed depression and the surface or subsurface drainage feeding it.
Treat the 15-foot tank and 25-foot field numbers as the floor; the consultant still has to map the depression itself. The soil consultant and TDEC need the site's actual shape, soils, slope, and water movement. A county-scale atlas flags the issue but does not set the permit line on one parcel.
Pull the current permit and site sketch first. TDEC lists a modification service when a house or site plan changes the initial or duplicate system area, when bedrooms change, or when a pool, garage, shop, barn, or other construction affects the existing layout. The records guide explains how to find the TDEC septic permit and site sketch.
Mark the proposed improvement on the same drawing and ask TDEC which review applies. Do this before design deposits, grading, utility work, or a building-permit deadline. Moving a well or building later can cost more than changing the concept while the site is still open.
Research and review. The Maury Septic editorial team checked this guide against current TDEC rules and service pages, plus TDEC's current permit-sketch standards, SSDS rules, online service definitions, and the Maury County geology atlas. Private-market costs are identified as planning ranges. For a specific property, rely on the issued permit and a written contractor scope.
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
Official rule index for permits, design, maintenance, soil consultants, installers, and fees.
Tennessee Department of Environment and Conservation
Conventional, repair, and alternative-system applications, plus soil-map requirements.
Tennessee Department of Environment and Conservation
State mapping standards for soil depth, restrictive layers, drainage, absorption rates, slope, site features, and SSDS interpretations.
Tennessee Geological Survey
State-published geologic, unstable-materials, flood-prone-area, mineral-resource, and sinkhole maps for Maury County.
Fifty feet, from both the tank and the disposal field to a water supply, under TN Rule 0400-48-01-.11. The issued site sketch controls the property. Soil conditions or a special investigation can change specified distances, so do not place a well from a generic diagram alone.
Ten feet, for both tanks and disposal fields, measured to property lines and easement boundaries. That number is only one part of fit. The field must also clear the house, water supply, and drainage features while preserving its duplicate area, and the issued permit controls the parcel.
No. TDEC says dividing land into tracts of five acres or larger is outside its stated subdivision definition, but that does not approve septic construction. Each proposed home still needs a compliant site and permit. A five-acre tract can lack usable soil, while a smaller parcel may have a workable approved layout.
It is protected soil reserved for a future disposal field if the initial field fails or must be replaced, sized at 100 percent of the original and drawn on the permit site sketch. Do not build, grade, compact, pave, install utilities, or place a pool in that reserved envelope.
Twenty-five feet from the disposal field and 15 feet from tanks or an ATS, for sinkholes and the other listed drainage features. A footnote in the rule allows those distances to change after special soil investigation. In Maury's karst terrain, map the entire depression and drainage pattern before relying on one measured edge.
This form is for installation, replacement, repair, and aerobic service requests. It does not calculate legal boundaries, map soil, set setbacks, or issue a TDEC permit.
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Related: Tennessee septic rules explained · septic permit guide · soil and site evaluation · sinkholes and septic · building over the drainfield · failed soil test options · septic records lookup · septic system cost · subdividing land with septic · wells and septic
Regulatory claims are checked against primary sources. Site-specific approval and pricing still require TDEC and a written installer estimate.