How much does it cost to install a septic tank and leach field?
Last updated July 10, 2026
Short answer
Installing a new septic tank and leach field (drain field) on a property without an existing system typically costs $10,000 to $20,000 in Windham County, plus permitting fees through your local health district.
New installation, as opposed to replacement, usually applies to new construction or a property converting from a failed cesspool to a modern system. The process starts with a soil and site evaluation to size the leach field correctly, followed by permitting, then excavation and installation of the tank and distribution piping. Costs rise on sites with ledge, wetlands setbacks, or limited usable area, all of which are common considerations in Windham County's rural terrain. Budget for the possibility of an engineered system if your site doesn't pass a standard percolation test.