HomeAdvisor puts replacing a septic tank on its own at $3,000 to $10,000, and says that's less than installing a new system because excavation is already done (HomeAdvisor, June 20, 2026). The ranges overlap, though: the same guide prices a whole new conventional (anaerobic) system at $3,000 to $8,000 (HomeAdvisor, June 20, 2026), and its perc-test guide gives $3,610 to $12,420 for a full system replacement (HomeAdvisor, June 19, 2026). Aerobic and mound systems run $10,000 to $20,000 to install (HomeAdvisor, June 20, 2026). The tank itself is only part of the price. HomeAdvisor says labor is 50% to 70% of an installation (HomeAdvisor, June 20, 2026).
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Tank prices by size, before installation (HomeAdvisor, June 20, 2026):
| Tank size | Typical house size | Tank price (range) |
|---|---|---|
| 500 gallons | 1 bedroom | $500 – $900 |
| 750 gallons | 2 bedrooms | $700 – $1,200 |
| 1,000 gallons | 3–4 bedrooms | $900 – $1,500 |
| 1,200 gallons | 5–6 bedrooms | $1,200 – $1,600 |
| 1,500 gallons | 6–7 bedrooms or small duplex | $1,500 – $2,500 |
Those bedroom pairings are HomeAdvisor's. Your county or state code sets the actual minimum, and some require more than this, e.g. Minnesota requires 1,500 gallons for a 4- or 5-bedroom home (Minn. R. 7080.1930, current rule). See septic tank size by bedrooms.
And by material (material only) (HomeAdvisor, June 20, 2026):
| Material | Price (range) | Trade-off |
|---|---|---|
| Concrete | $700 – $2,000 | Durable but can crack over time |
| Plastic | $500 – $2,000 | Light and crack-resistant, but can be damaged during installation |
| Fiberglass | $1,200 – $2,000 | Strong and won't crack, but can shift in the soil |
HomeAdvisor's pages aren't consistent on tank-only replacement: its inspection guide's repair table lists tank replacement at just $500 to $2,500 (HomeAdvisor, June 19, 2026). Get a written quote. Small cracks and leaks can often be repaired for $200 to $4,000, depending on the damage (HomeAdvisor, June 20, 2026). HomeAdvisor's rule of thumb: if repair costs exceed 50% of the replacement cost, replacing "might be more cost-effective," weighed against the system's age, the severity of the problem and any warranty (HomeAdvisor, June 20, 2026). The sources disagree on how long a tank lasts. HomeAdvisor's installation guide says 15 to 20 years (HomeAdvisor, June 20, 2026); its inspection guide gives concrete 20 to 40 years and plastic or fiberglass 30 to 40 (HomeAdvisor, June 19, 2026). EPA says a concrete tank may last 50 years or more, though older tanks may not be as well built as newer ones (EPA, March 11, 2026). See how long a septic system lasts and septic repair costs.
If the drain field is the problem, a new tank won't fix it. EPA notes that in drain fields more than 25 to 30 years old, the biomat at the bottom of the trenches can thicken and reduce the field's ability to discharge water (EPA, March 11, 2026). If the soil fails a perc test, HomeAdvisor says the site has to be modified or an alternative system installed (HomeAdvisor, June 19, 2026); EPA describes mound and aerobic systems as options for shallow soil, high groundwater and poor soil (EPA, May 4, 2026). Use the calculator for a full-system estimate for your bedrooms, soil and state.
The calculator gives an itemized installed-cost estimate for your bedrooms, system type, soil and state.
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