The numbers that are published
In Maine, the design starts at $700 and a conventional system starts at $18,000. That start assumes a lot that percolates cleanly and a layout a standard gravity design can serve.
No New Hampshire starting price is published on this site. New Hampshire design and permitting sit with the state, and the system gets priced from the lot after the soils are known.
Why the rest is not published
An engineered system, a pump system and a mound are different designs, and the thing that decides between them is what the test pit shows. Printing a figure for a design nobody has drawn yet would be a guess with a dollar sign on it. The soils come first, then the design, then the price.
What the test pit decides
- Soil and perc rate. Clean sand keeps a system conventional. Silt and clay push it up the ladder.
- Ledge. Rock close to the surface changes the excavation and can rule out a conventional field.
- Water table. Groundwater near the surface is the usual reason a system has to be raised.
- Setbacks. Wells, property lines, surface water and the shoreland line all hold the field off ground that otherwise looks fine.
- Bedroom count. Systems are sized by bedrooms, not bathrooms. Adding a bedroom, or an ADU, is a capacity question before it is a plumbing question.
Replacing a system that has failed
A replacement adds the removal of what is there: pumping the tank, crushing or pulling it, and disposing of the old field. It also narrows the options, because a failed system is a deadline as well as a design. That work is priced from the site, the same way a new system is.
Septic and an ADU
Both states now require towns to allow an ADU on most single-family lots, and on an unsewered lot the septic is what decides whether the unit happens. Whether your lot is on a system or on a town main is the first question, and private septic vs town sewer covers what each one means over the years.
Get the pit dug
Book a land review and we will put a hole in the ground before anyone puts a number on paper. Call (978) 987-0089 if the system has already failed.
The 2-minute calculator is on instant pricing. Published packages are on the ADU models.