Septic Tank Installation Cost in Knoxville, TN

On Knox County clay, a conventional system for a three-bedroom house typically runs $16,000 to $22,000, mostly because clay needs about 2,250 sq ft of drain field.

New septic tank installation at a Knox County, TN property — septic service scene

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Price guide: Typically $16,000 to $22,000 for a three-bedroom conventional system on clay. Use the calculator below for your house and soil.

Why it costs more on clay

The drain field is sized by how fast the soil takes water. Clay is rated at 0.20 gallons a day per square foot, sand at 1.20. A three-bedroom house puts out 450 gallons a day, so it needs 2,250 sq ft of field on clay and 375 sq ft on sand. That 1,875 sq ft difference adds roughly $13,000.

Same house, different soil

Conventional system, Knox County, 2026, from typical Knoxville-area prices. Estimates only; your soil report and site visit set the real figure.
Bedrooms	Soil	Drain field	Tank	Typical installed range
3	Clay (typical Knox County)	2,250 sq ft	1,000 gal	$16,000 to $22,000
3	Silty clay	1,500 sq ft	1,000 gal	$11,500 to $16,000
3	Loam	750 sq ft	1,000 gal	$7,000 to $9,500
3	Sand	375 sq ft	1,000 gal	$5,000 to $6,500
2	Clay (typical Knox County)	1,500 sq ft	1,000 gal	$11,500 to $16,000
4	Clay (typical Knox County)	3,000 sq ft	1,250 gal	$21,000 to $28,000
5	Clay (typical Knox County)	3,750 sq ft	1,500 gal	$25,500 to $35,000

Septic tank cost on its own

The tank is the smaller part of the bill. Installed, a 1,000-gallon tank typically runs about $1,600, a 1,250-gallon tank about $1,950 and a 1,500-gallon tank about $2,400. On Knox County clay, the drain field is most of the cost of a new system.

What else moves the price

A failed perc test that calls for a mound or aerobic unit.
Access for the excavator, slope and rock.
A pump, if the field has to sit uphill from the house.
Removing an old tank.

Helpful answers

Questions people ask

How much does a new septic system cost in Knoxville?

For a three-bedroom house, typically $16,000 to $22,000 on clay, $11,500 to $16,000 on silty clay and $5,000 to $6,500 on sand. A mound system adds roughly $10,000 to $14,000. The soil report and a look at the site set your exact price.

Towns we cover

Also covered: Lenoir City, Loudon, Greenback, Oliver Springs, Rocky Top, Maynardville, Blaine, Dandridge, Jefferson City, New Market, Pigeon Forge, Townsend, Friendsville.