Westchester County, NY Septic Regulations & Compliance Program

Short answer: Westchester County's Department of Health oversees septic permitting, inspection and professional licensing countywide, on top of New York's statewide minimum design standards. Roughly 40,000 homes countywide run on septic -- about 27,000 of them inside the NYC watershed portion of the county, where the county also runs a dedicated program to lower the cost of septic repairs and sewer connections.

Last updated: November 2026. This page summarizes public Westchester County and New York State information for homeowner reference and is not legal advice — always confirm current requirements and program terms directly with the Westchester County Department of Health.

Who regulates septic systems in Westchester County

New York delegates most onsite wastewater oversight to county and local health departments rather than regulating directly at the state level. NYSDOH sets minimum statewide design standards (Appendix 75-A, "Wastewater Treatment Standards – Residential Onsite Systems"), but permitting, inspection and enforcement happen locally. In Westchester, that's the County Department of Health: it issues septic permits, inspects new and repaired systems, and licenses the professionals who install, pump and service them.

Septic use in Westchester is concentrated in the county's northern towns, away from the municipal sewer networks that cover most of southern Westchester. Lewisboro, for example, has been specifically identified as a majority-septic community. If you're unsure whether a specific address is on septic or sewer, the County Department of Health's septic systems program page is the authoritative source.

The NYC Watershed septic repair cost-share program

A meaningful share of Westchester's septic systems -- roughly 27,000 of the county's ~40,000 total -- sit inside the New York City watershed, the land area that drains into NYC's drinking-water reservoir system. Because a failing septic system in the watershed is also a water-quality issue for New York City's supply, Westchester County runs a program specifically aimed at lowering the cost of septic repairs and sewer connections for homeowners in that watershed area. The county has estimated that roughly 1 in 10 watershed-area systems may need repair.

This is conceptually similar to the compliance-and-cost-share programs that exist in other NY counties with heavy septic/cesspool reliance (see our New York state page for the parallel in Suffolk County) -- a recognition that keeping septic systems in good repair is a shared public-health and water-quality interest, not just a private homeowner expense.

What this means for you as a homeowner

• If your property is in northern Westchester, there's a real chance it's on septic rather than sewer -- confirm with your town or the County Health Department if you aren't sure.
• If you're in the NYC watershed portion of the county and your system needs repair, check your eligibility for the county's cost-share program before paying for a repair or sewer connection out of pocket.
• Any septic work -- pumping, repair, or installation -- should go through a professional the County Department of Health recognizes; permitting and inspection run through that office, not a town building department, for septic specifically.
• Septic systems generally need pumping on a multi-year cycle (commonly every 3–5 years depending on tank size and household use) -- staying ahead of that schedule is the most effective way to avoid becoming one of the "needs repair" statistics the watershed program exists to address.

Sources

• Westchester County Department of Health — Septic Systems program (health.westchestergov.com/septic-systems)
• Westchester County government press release, "Westchester County Launches Program To Lower Costs For Septic Repairs And Sewer Connections In NYC Watershed" (westchestergov.com)
• The Journal News / lohud.com reporting on Westchester septic system counts (2015)
• NYSDOH Appendix 75-A, Wastewater Treatment Standards – Residential Onsite Systems