How much does drain field replacement cost?
Last updated July 10, 2026
Short answer
Drain field (leach field) replacement alone, without a new tank, typically costs $5,000 to $15,000 in Windham County, depending on field size and soil conditions. Difficult sites requiring an engineered or alternative system can run higher.
The drain field is usually what fails first in an aging septic system, often from age, being driven or built over, or years of an undersized or overloaded tank sending solids downstream. Field size is set by the home's number of bedrooms and the soil's percolation rate, so a larger home or poor-draining soil means a bigger, more expensive field. Signs a drain field is failing include soggy ground, unusually lush grass over the field, or slow household drains, all covered in more detail in our failing septic system guide.