Septic Tank Installation Cost Calculator
Estimate septic tank install or replacement from tank size, whether the drain field is included, and soil difficulty. Midpoints are residential conventional systems — not mound or commercial plants. Click any i for detail.
Your septic project
Tank size
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Tank size
Bedroom count and local code set capacity. 1,000 gal suits many 3-bedroom homes; larger houses often need 1,250–1,500 gal. |
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Job type
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Job type
New install includes a drain-field allowance. Tank-only replace assumes the field still passes inspection. Full system replace rebuilds tank and field. |
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Soil / site class
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Soil / site class
Poor perc tests, high water tables, or engineered fields raise excavation and field cost sharply. |
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Your state
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Your state
Scales midpoints for typical state-level labor and material costs versus the U.S. average — not an on-site bid. |
Options
How to use this calculator
- Select tank gallon size for your bedroom count / code.
- Choose new install, tank-only replace, or full system replace.
- Set soil difficulty and optional pump-out or permit lines.
- Pick your state and review the breakdown.
Results explained
The estimate itemizes tank materials, excavation & set labor, and a drain-field allowance when the job type includes one. Soil class and job type multiply labor/field lines; state scales the U.S. midpoints.
Quick reference: septic install midpoints
U.S.-average educational midpoints before soil and state scaling.
| Item | 1,000 gal | 1,250 gal | 1,500 gal | Notes |
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| Tank materials | $1,400 | $1,700 | $2,100 | Concrete or plastic |
| Excavation & set | $3,200 | $3,600 | $4,100 | Before soil multiplier |
| New drain field | ~$6,500 | ~$6,500 | ~$6,500 | Conventional trench |
| Full field rebuild | ~$9,500 | ~$9,500 | ~$9,500 | Full system replace |
Tank-only replace uses ×0.72 on excavation (no new field). Engineered fields can exceed these bands.
How the estimate is built
Tank materials are size-based flats. Excavation ≈ size excav midpoint × job multiplier × soil × state. Drain-field allowance applies on new (~$6,500) or full replace (~$9,500), scaled by soil. Pump-out ~$450; permit ~$650. Band ≈ 80%–135%.
Example scenario
A new 1,000 gal install on typical soils at U.S. average is about $1,400 tank + $3,200 excav + $6,500 field + $650 permit ≈ $11,750.
FAQ
Is a perc test included?
No. Perc tests, soil borings, and design fees are usually separate and required before a permit.
Aerobic or mound systems?
Those engineered systems often cost more than the “difficult soils” band — get a designer quote.
Can I DIY a septic tank?
Most jurisdictions require licensed installers and inspections. This tool assumes professional install.