When there isn't enough usable soil depth for effluent to be treated naturally, a pump lifts it up into an engineered mound of sand and gravel built above natural grade — a synthetic soil layer the site doesn't have. It's the standard remedy for a failed perc test. Effective almost anywhere, but the most expensive and land-hungry option, and it needs a working pump plus periodic maintenance of the pump chamber.
Shallow soil over rock or clay, a high water table, or a lot too thin/steep for a standard field.
| Bedrooms | Estimated installed cost |
|---|---|
| 1–2 bedrooms (750-gal tank) | $8,500 – $17,000 |
| 3 bedrooms (1,000-gal tank) | $10,000 – $20,000 |
| 4 bedrooms (1,250-gal tank) | $11,500 – $23,000 |
| 5+ bedrooms (1,500-gal tank) | $13,500 – $27,000 |
Soil condition and region can move these numbers 25–35% in either direction — use the full calculator for a range tuned to your site.
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