How much does septic tank replacement cost in Tennessee?
HomeGuide’s 2026 guide puts septic tank replacement at $3,500 to $8,500 on average for a 3 or 4 bedroom home. Tank size, material and the gravel or fill dirt needed to set the tank move the number. We look at your site and hand you one price on a free on-site estimate.
What goes into the cost to replace a septic tank?
A septic tank replacement bill comes in parts. Angi’s cost guide, updated October 2026, puts a 1,000 gallon tank at $900 to $1,500 for the tank alone.
Labor is the larger share. Angi says labor accounts for 50 to 70 percent of a septic system’s total cost. Angi also says excavation can add $1,500 to $6,300 if it is billed separately. Angi lists old septic tank removal at $45 to $200 per hour.
Our septic tank replacement work includes the permit. We look at the site and hand you one price on a free on-site estimate.
Each published range below carries its source.
| Line item | Published range | Source |
|---|---|---|
| 750 gallon tank alone | $700 to $1,200 | Angi, 2026 |
| 1,000 gallon tank alone | $900 to $1,500 | Angi, 2026 |
| 1,200 gallon tank alone | $1,200 to $1,600 | Angi, 2026 |
| 1,500 gallon tank alone | $1,500 to $2,500 | Angi, 2026 |
| Excavation, if billed separately | $1,500 to $6,300 | Angi, 2026 |
| Old septic tank removal | $45 to $200 per hour | Angi, 2026 |
| Repair permit (TDEC counties) | No fee | TDEC fee schedule |
| Repair construction inspection (TDEC counties) | $100 | TDEC fee schedule |
| Abandonment inspection (Williamson County) | No cost | Williamson County, Section 32 |
| Tank replacement, 3 or 4 bedroom home | $3,500 to $8,500 on average | HomeGuide, 2026 |
| Tank and drain field together | $4,500 to $20,000 | HomeGuide |
| Repairing or replacing a malfunctioning conventional system | $5,000 to $15,000 | EPA |
Is replacing just the tank cheaper than a new septic system?
In HomeGuide’s figures, yes. A tank-only job keeps the drain field you have. HomeGuide’s drain field cost guide puts a septic tank and drain field replaced together at $4,500 to $20,000. The EPA puts repairing or replacing a malfunctioning conventional system at $5,000 to $15,000.
If the field is failing too, our guide to drain field replacement cost in Tennessee breaks that part down. A whole new system has its own guide: what a new septic system costs in Tennessee.
One free on-site estimate prices whichever job you need.
Can a septic tank be repaired instead of replaced?
Sometimes. Baffles and effluent filters can be replaced while the tank stays in the ground. That is septic tank repair work.
In Williamson County, the county’s Department decides whether a malfunctioning system, or any part of it, needs complete replacement. That is Section 34 of the county regulations. Our guide to septic tank repair vs replacement walks through the decision.
What permit does septic tank replacement in Tennessee need?
It depends on the county. Williamson County runs its own septic program. Most counties around it permit through TDEC, the Tennessee Department of Environment and Conservation.
In the TDEC counties, state rule 0400-48-01 requires a repair permit to install a septic tank that corrects a failure. TDEC’s fee schedule lists no fee for that permit and $100 for the repair construction inspection.
In Williamson County, Section 34 treats replacing a malfunctioning tank as a repair. The property owner contacts the Department, which investigates the system. The property owner, a licensed septic installer, a building contractor or their agent may request the repair permit. The county issues no septic repair permit where a property has access to public sewer.
The county’s repair page points property owners with a failing system to its verified list of service providers. We file the permit in whichever office your address calls for. Our guide to septic permits in Williamson County covers that office.
Before anyone digs, Tennessee 811 needs at least three working days’ notice for a normal locate. Utility locators do not mark private lines, such as the home’s own sewer or water line.
Does the new septic tank have to be bigger than the old one?
The new tank has to meet today’s rules, whatever the old tank held. Williamson County’s Section 34 says every repair or modification follows the current regulations. In the TDEC counties, the state rules also apply when a failure is corrected.
State rule .08 and Williamson County’s Table S14-1 size a home’s tank by bedrooms, with the same numbers. A house with 2 or fewer bedrooms gets 750 gallons, 3 bedrooms get 900 and 4 get 1,000. Each bedroom past 4 adds 250 gallons, so an undersized old tank gets a bigger replacement.
In the TDEC counties, state rule .09 says a septic tank must be watertight and structurally sound. Tanks installed after January 1, 1991 must be a two-compartment design. So a single-compartment tank gets replaced with a two-compartment one.
In Williamson County, moving a working system to a larger tank is a modification, which needs a permit too. Our guide to septic tank size in Tennessee has the full chart.
What happens to the old septic tank?
In Williamson County, Section 32 says a septic tank that goes out of use must be abandoned. Each of the county’s three methods starts with pumping.
- Collapse it. Pump it, demolish the walls and backfill with gravel to within 12 inches of the surface. Soil goes on top, crowned for settling.
- Remove it. Pump it, dig it out, break it up and haul it to an approved disposal site. Then backfill the hole.
- Fill it. Pump it, then fill it completely with gravel, concrete or another material the Department approves.
A state-permitted pumping contractor does the pumping. The property owner, or someone acting for them, gives the Department proof of pumping. The Department is notified after the work and before the tank is covered. It inspects and approves the abandonment at no cost.
In the TDEC counties, the permit office sets the steps for the old tank. We handle permits start to finish, so those steps are part of the job.
What does a new septic tank cost by material, and how long does it last?
Angi’s 2026 guide lists plastic tanks at $500 to $2,000 and concrete at $700 to $2,000. Angi lists fiberglass at $1,200 to $2,000, all for the tank alone.
HomeGuide’s 2026 septic system guide says a heavy concrete tank will not float when the water table is near it. A lightweight plastic tank may float upward there.
HomeGuide says steel septic tanks typically last 20 to 25 years, while concrete tanks often last longer than 40 years. Steel tanks are no longer installed, so an old steel tank gets replaced with another material.
A free on-site estimate turns these ranges into one price for your property.
Frequently asked questions
What’s the average price to replace a septic tank?
HomeGuide’s 2026 guide puts septic tank replacement at $3,500 to $8,500 on average for a 3 or 4 bedroom home. Tank size, material and the gravel or fill dirt to set the tank move the number. We look at the site and hand you one price on a free on-site estimate.
How long do septic tanks last before you have to replace them?
HomeGuide says steel septic tanks typically last 20 to 25 years, while concrete tanks often last longer than 40 years. HomeGuide also says to consider replacing a tank that is more than 40 years old or cracked. Frequent repairs, or pumping more often than it should, are signs too.
Can a septic tank be repaired instead of replaced?
Sometimes. Baffles and effluent filters can be replaced while the tank stays in the ground. In Williamson County, the county’s Department decides whether a malfunctioning system, or any part of it, needs complete replacement. Our guide to septic tank repair vs replacement covers that decision.
Do I need a permit to replace a septic tank in Tennessee?
Yes. In the TDEC counties, state rule 0400-48-01 requires a repair permit to install a tank that corrects a failure. TDEC’s fee schedule lists no fee for that permit and $100 for the repair construction inspection. Williamson County issues its own repair permit. We price the job on a free on-site estimate.
What happens to the old septic tank?
In Williamson County, Section 32 says a tank that goes out of use must be abandoned. A state-permitted pumper empties it first. Then it is collapsed and backfilled, removed, or filled with gravel or concrete. The county inspects the work at no cost. In the TDEC counties, the permit office sets the steps.
Is a plastic or concrete septic tank cheaper?
Plastic can come in lower. Angi’s 2026 cost guide lists plastic tanks at $500 to $2,000 and concrete at $700 to $2,000. HomeGuide says a lightweight plastic tank may float upward when the water table is near the tank. A heavy concrete tank will not. A free on-site estimate turns that into one price.
Does the new tank have to be bigger than the old one?
It has to meet today’s size table, whatever the old tank held. State rule .08 and Williamson County’s Table S14-1 list 750 gallons for 2 or fewer bedrooms. Both list 900 for 3 bedrooms and 1,000 for 4, plus 250 per added bedroom. In the TDEC counties, a new tank must be a two-compartment design.
How much does a 1,000 gallon septic tank cost?
Angi’s 2026 cost guide puts a 1,000 gallon tank at $900 to $1,500 for the tank alone. Installation labor and digging come on top of that. Under the Tennessee tables, 1,000 gallons is the size for a 4 bedroom house. We look at the site and hand you one price on a free on-site estimate.
Septic Superior is a family septic company based in Thompson’s Station. More than 20 years of septic work in Williamson County sit behind the company. We replace septic tanks as part of our septic system installation and replacement work. We also handle the permit start to finish. Call (615) 957-9682 or use our contact form for a free on-site estimate, and we hand you one price.