Septic System Cost Estimator
Enter bedrooms and soil conditions for septic system pricing.
Runs entirely in your browser — your numbers never leave this page.
How it works
Septic cost = system type × size × soil difficulty:
- Conventional (~$9k+): tank + gravel leach field — cheapest, needs good perc.
- Chamber (~$12k): plastic chambers instead of gravel — smaller footprint.
- Mound (~$20k): built-up sand mound for high water tables or shallow soil.
- Aerobic ATU (~$22k): mini treatment plant — for the toughest sites, with ongoing service contracts.
- Sized by bedrooms: not bathrooms — bedrooms predict wastewater flow.
- Perc test first: always test soil before buying rural land. No perc = no house.
- Maintenance: pump every 3–5 years (~$400). Neglect kills $20k systems.
Frequently asked questions
How much does a septic system cost?
Conventional ~$9k+, chamber ~$12k, mound ~$20k, aerobic ~$22k — scaled by bedrooms and soil difficulty.
What is a perc test?
A soil percolation test measuring drainage — it determines what system type your site allows. Always test before buying land.
How long do septic systems last?
25–40 years with pumping every 3–5 years. Neglected systems die young.
How often should I pump?
Every 3–5 years for a typical household (~$400). Garbage disposals shorten the interval.
What kills septic systems?
Grease, wipes ("flushable" aren't), harsh chemicals, driving over the field, and never pumping.
Conventional vs mound?
Conventional needs good deep soil. Mound is the engineered answer for high water tables or shallow bedrock — at ~2x the price.
Do I need a permit?
Yes — health department permits, perc test, and inspections are mandatory everywhere.
Is replacement more expensive?
Yes — 20–40% more than new installs, due to old-system abandonment and working around existing structures.
Septic vs sewer?
Sewer: $5k–15k connection + monthly bills forever. Septic: bigger upfront, ~$400/year after. Do the 20-year math.
What should I never flush?
Wipes, grease, coffee grounds, medications, harsh chemicals — the field is a living ecosystem, treat it like one.