How much does a new septic system cost in Windham County, CT?
Last updated July 10, 2026
Short answer
A complete new septic system, tank and drain field, typically costs $10,000 to $20,000 in Windham County, with rocky or high-water-table sites running higher. Simple, easy-access sites on level ground tend to land toward the lower end.
Windham County's terrain varies enough to swing this estimate meaningfully. Rocky or ledge-heavy sites, common in the northern part of the county, often require blasting or an engineered system, which raises cost well past the typical range. A high water table or small lot can require an alternative or mound system instead of a standard gravity drain field, which also costs more. Permitting through your town's health district is required before installation begins, and a licensed installer will need a soil test and site evaluation to determine which system type your property can support.