What does a septic system cost in Tennessee?
The cost of a septic system in Tennessee depends mostly on the soil and the system type the soil allows. A conventional system on good soil costs the least. Alternative systems, needed where soil or slope is poor, cost more. TDEC's own fees are $400 for a conventional permit plus a $100 inspection, and $500 for an alternative permit plus a $200 inspection.
Written by Morgan's Concrete and Excavation. Published 2026-10-20.
What decides the type of system?
The soil decides. A TDEC Environmental Scientist evaluates the site, and some sites need a soils map from a licensed soil scientist. Deep, well drained soil usually allows a conventional system with a tank and a gravel or gravelless drain field. Shallow soil, rock, a high water table or steep ground can require an alternative system, and large or alternative systems need a design from a licensed engineer.
That is why no honest contractor can quote a septic system before the permit and the soil evaluation are in hand. The permit sets the system type, the field size and the layout.
How big does the tank have to be?
Tennessee rules set the minimum tank size by the number of bedrooms: 750 gallons for two bedrooms or fewer, 900 gallons for three, 1,000 gallons for four, and 250 gallons more for each bedroom after that. The drain field is sized from the permit's design flow and the soil.
- 2 bedrooms or fewer: 750 gallon minimum tank
- 3 bedrooms: 900 gallon minimum tank
- 4 bedrooms: 1,000 gallon minimum tank
- Each added bedroom: 250 more gallons
What else changes the installed price?
Rock is the biggest wildcard on Upper Cumberland lots. Hitting rock while digging the tank hole or the field trenches adds machine time. Access matters too: a tight lot, a long run from the house to the field, or a field across a slope all add work. A pump tank, when the field sits uphill from the house, adds equipment and power.
Permit and inspection fees are the smallest part of the total. TDEC charges $400 for a new conventional system up to 1,000 gallons per day plus a $100 construction inspection, and $500 for a new alternative system plus a $200 inspection.
- System type set by the soil evaluation
- Tank size set by bedrooms
- Rock, slope and access
- Pump tank if the field sits uphill
- TDEC permit and inspection fees
How do I get a firm number?
Apply for the TDEC permit first, since the permit defines the system. Then send Morgan's the permit and the site plan through the request form at /request-estimate, or call the office. Joe walks the site, checks access and the field location, and puts the price in writing. Because Morgan's also does the excavation, grading and site prep, the septic system can be planned together with the house pad and driveway.
Related questions
How much is a septic permit in Tennessee?
TDEC charges $400 for a new conventional system up to 1,000 gallons per day plus a $100 inspection, and $500 for a new alternative system plus a $200 inspection.
What size septic tank does a 3 bedroom house need in Tennessee?
Tennessee rules set a 900 gallon minimum tank for a three bedroom home.
Why can't a contractor quote a septic system before the permit?
The TDEC permit and soil evaluation decide the system type, the drain field size and the layout, and those set most of the installed cost.
Does Morgan's install septic systems?
Yes. Morgan's installs septic systems as part of its excavation and site work across Cookeville and the Upper Cumberland.
Planning a septic installation project
See how Morgan’s handles septic installation jobs around Cookeville, or request a written estimate for your own project.