Septic Tank Installation Cost Calculator
The type of system moves the price more than anything else: a conventional gravity system costs $3,000 to $8,000, while mound and aerobic systems run $10,000 to $20,000. Septic tank installation cost for a complete new septic system usually falls between about $3,600 and $12,000, and septic system replacement cost averages about $6,100 to $8,000.
Septic tank installation cost by type
| System | Installed cost |
|---|---|
| Conventional (gravity) | $3,000 to $8,000 |
| Chamber | $5,000 to $12,000 |
| Mound system | $10,000 to $20,000 |
| Aerobic treatment unit | $10,000 to $20,000 |
A caution on these figures: several price guides publish identical tables, so they probably share one data source rather than confirm each other independently.
The calculator adds a perc or soil test, usually $700 to $2,000 (some areas $600 to $800), and a permit, $450 to $2,300.
When only one part has failed
| Job | Typical cost |
|---|---|
| Septic tank replacement cost, installed | $2,300 to $6,500 |
| Drain field replacement cost | $3,500 to $12,000 |
| Septic pump replacement cost | $200 to $1,400 |
| Risers and lids | $300 to $600 |
Some quotes for a tank run far higher, $9,500 to $15,000 with removal of the old one. A new leach field averages close to $7,900.
The tank alone, before installation, runs $700 to $2,000 in concrete, $500 to $2,500 in plastic and $1,200 to $2,000 in fiberglass. A 1,000-gallon tank is $900 to $1,500 and a 1,500-gallon tank $1,500 to $2,500.
Sizing the tank to the house
Bedrooms set the size. Minnesota’s code is a clear example: 1,000 gallons for up to 3 bedrooms, 1,500 for 4 or 5, 2,000 for 6 or 7. Many states require at least 1,000 gallons.
A maintenance calendar that delays replacement
- Every 3 years: inspection, which the EPA recommends at least this often for household systems (alternative systems generally once a year).
- Every 3 to 5 years: pumping, the EPA’s typical interval for household tanks.
- 20 to 30 years: the expected life of a tank.
- Up to 50 years: how long a leach field can last.
Warning signs and insurance
Watch for puddles or standing water over the tank or field, sewage odors, unusually green or mushy grass, slow drains, backups and gurgling. The EPA warns that an overloaded drain field can flood and push sewage to the surface or back into toilets and sinks.
Home insurance may pay to repair a septic tank damaged by an event your policy covers. Check the policy wording for what counts as covered damage.