Do I need a permit to repair my septic system in Davidson County?

Who regulates what

Two layers, and knowing which is which saves confusion.

The state. TDEC runs the Subsurface Sewage Disposal Program, which sets the rules for subsurface sewage disposal systems across Tennessee. Septic tank pumping contractors specifically are governed by Tenn. Comp. R. & Regs. 0400-48-01-.20.

The county. Davidson is a contract county — it administers its own septic program rather than having the state administer it directly. That means local requirements apply in addition to state rules, and your first call is local.

In Davidson County, Metro Public Health’s Septic and Sewage Disposal Systems division handles soils interpretation, design of on-site subsurface sewage disposal systems, technical consulting, land use and development, monitoring of percolation tests, and groundwater protection.

Environmental Engineering Services: 615-340-5604.

When a permit is required

A permit is required for the construction, installation, alteration, extension or repair of a subsurface sewage disposal system. In practice:

Work	Permit?
Routine pumping	No — maintenance
Cleaning the effluent filter	No
Replacing a baffle inside the tank	Generally no, but confirm locally
Fitting risers	Generally no, but confirm locally
Repairing or replacing a drain field	Yes
Installing a new system	Yes
Extending a system for an added bedroom	Yes
Replacing a tank	Yes

If in doubt, one call to 615-340-5604 settles it, and it is a far cheaper call than an unpermitted field.

Who holds the permit

Persons who construct, install, alter, extend or repair a system are required to hold a valid permit for that work. Contract counties, Davidson included, may require an additional local permit.

So the practical question to ask a contractor is not “will this be permitted?” but “are you permitted to do this work in Davidson County, and will you pull the permit?” A contractor who is vague about it is telling you something.

What new systems require

Tennessee permitting requires a site evaluation including a soil morphology assessment — an actual soil scientist assessing the profile, not a guess based on the neighbouring lot.

That requirement makes a great deal of sense here. Middle Tennessee is karst: limestone dissolving into fractured bedrock, with frequently shallow clay loam above it. Percolation varies sharply across short distances, and effluent entering fractures rather than percolating through soil is the specific risk the assessment exists to catch.

The evaluation determines the field sizing, and on slow soils it will size it generously — which is why Middle Tennessee fields skew large.

Other records Metro holds

While you have them on the phone, two records are worth asking about:

• The approved bedroom count for an existing residence, along with approval and inspection dates
• Guidance on the reserve area requirement — your parcel must retain sufficient area to replace the system if it fails, and Metro will help determine acceptable boundary locations if you are revising them

Both matter at sale, and both are easier to deal with before someone else raises them.

Bottom line

Pumping needs no permit; anything that alters the system does. Davidson runs its own program, so call 615-340-5604 rather than assuming state guidance covers it. For work that needs permitting we will tell you before starting — call (615) 234-9048.