New Hampshire · septic cost & sizing
New Hampshire septic system cost & tank size requirements
A conventional septic system in New Hampshire runs about $5000–$15100 installed — about 12% above the US average. The estimator below is preset to New Hampshire's regional cost index.
Estimate only — get 2–3 quotes from licensed installers. Regional index is a calibration default; New Hampshire costs vary by county and site.
New Hampshire costs
What a septic system costs in New Hampshire
Construction and labor in New Hampshire run about 12% above the US average, so a standard conventional system lands around $5000–$15100 all-in (tank, drain field, excavation, and the soft costs of a perc test, design, and permits). Soil that fails a perc test is the biggest budget risk anywhere — it forces an alternative system, which can double or triple the figure. Adjust the soil-difficulty and system-type fields above to see the swing.
New Hampshire tank-size requirement
New Hampshire works from a baseline tank minimum of about 1,000 gallons for a typical home, increasing with bedroom count. To size your own tank against the code minimum, use the septic tank size calculator.
Perc test & permitting in New Hampshire
DES-approved designer; deep-hole and perc test. The soil evaluation determines whether a conventional drain field will work or whether you need an alternative system — size it with the drain field calculator.
Finding septic services near you in New Hampshire
We don't sell leads or hand your details to contractors. Instead: contact your county health department for a list of licensed installers, get two or three written quotes, and use the independent estimate above to compare them fairly. Knowing the standard cost is the best protection against an inflated quote.
Frequently asked questions
How much does a septic system cost in New Hampshire?
A conventional gravity system in New Hampshire typically runs about $5000–$15100 installed — about 12% above the US average. Alternative systems for difficult soil (mound, sand filter, or aerobic treatment units) cost considerably more. Use the calculator above for a figure tuned to your home and soil.
What size septic tank is required in New Hampshire?
New Hampshire works from a baseline minimum of about 1,000 gallons for a typical home, rising with bedroom count. Confirm the exact requirement with your local health department, which has the final say.
Do I need a perc test in New Hampshire?
DES-approved designer; deep-hole and perc test. A perc or soil evaluation is part of permitting almost everywhere, so budget for it.
How do I find septic installers near me in New Hampshire?
Ask your county health department for a list of licensed installers and designers, then get two or three written quotes. Bring the independent estimate from this page so you can compare quotes on equal footing.