Drain field replacement cost
Septic drain field replacement cost
Replacing a drain field (leach field) usually runs $3,000–$15,000+. The estimator below is preset to drain-field-only — adjust soil difficulty and state for your range.
Estimate only — get 2–3 quotes from licensed installers. Coefficients are national calibration defaults (June 2026); your costs will vary.
The short answer
What a new drain field costs
A drain field replacement typically costs $3,000–$15,000. The biggest drivers are the size of the field (set by your home's design flow) and the difficulty of the soil and site. An easy, level lot with good soil and a small home sits near the bottom of that range; poor soil, a high water table, rock, or slope pushes toward the top — and if the soil no longer supports a conventional field at all, a mound or sand filter alternative can run well past $15,000.
Why the field is usually first to go
The drain field is the part of a septic system that does the final job of letting treated water soak into the soil. When a tank is not pumped on schedule, solids carry over and clog the soil pores — and once the soil is clogged, no amount of pumping brings it back. That is why regular pumping is the cheapest insurance against a five-figure field replacement.
To size a replacement field for your home and soil, use the drain field size calculator; bring both the size and the cost range to your installer.
Frequently asked questions
How much does it cost to replace a septic drain field?
Most drain field (leach field) replacements run $3,000–$15,000. Easy soil and a small field sit at the low end; difficult soil, a high water table, or a large home pushes toward the top — and a switch to a mound or sand filter can exceed it.
Why do drain fields fail?
The most common cause is a tank that was not pumped, so solids washed into the field and clogged the soil. Other causes are hydraulic overload, roots, compaction from vehicles, and simple old age.
Can a drain field be repaired instead of replaced?
Sometimes. Jetting, terralifting, or adding a new lateral can buy time, but a field that has truly clogged usually needs replacement. A failed field is the single most expensive common septic failure.
How long does a drain field last?
A conventional drain field typically lasts 20–30 years with proper tank pumping. Skipping pumping is the fastest way to shorten that to a decade or less.
Do I need a new perc test to replace the field?
Usually yes. A replacement is permitted to current code, so the soil is re-evaluated; if it no longer passes, you may be routed to an alternative system. Budget for the perc test and design.