Updated 18 April 2026
Cesspools - single-chamber pits that discharge raw sewage directly into surrounding soil without treatment - are being phased out across the Northeast under state and county mandates. Suffolk County NY requires conversion on property sale. Parts of Massachusetts, New Jersey, and New York have similar rules. Conversion cost: $5,000-$25,000, with grants of up to $20,000 available in Suffolk County.
Active Mandate Jurisdictions
A cesspool is a simple porous-walled pit buried in the ground. Liquid sewage seeps through the pit walls into surrounding soil, while solids accumulate at the bottom. There is no treatment - raw sewage, including pathogens and nutrients, goes directly into the soil. On Long Island, where hundreds of thousands of homes have cesspools within feet of the water table, the groundwater contamination is severe and well-documented.
A modern septic system (and especially an innovative/alternative IA system required in many cesspool-replacement mandates) provides two or three stages of treatment before effluent reaches the soil. The treated effluent is significantly cleaner - nitrogen levels reduced by 70-90% with IA systems vs zero reduction with a cesspool.
| Line Item | Low | Typical | High |
|---|---|---|---|
| Cesspool pump-out and decommission | $1,000 | $1,800 | $2,500 |
| Site evaluation and perc test | $600 | $1,000 | $1,500 |
| Engineering design (IA or conventional) | $1,000 | $2,000 | $3,500 |
| Permits and fees | $500 | $1,000 | $2,000 |
| New septic or IA system installation | $4,000 | $12,000 | $20,000 |
| Total conversion cost | $5,500 | $17,800 | $29,500 |
| Minus Suffolk County grant (eligible homes) | - | -$20,000 | -$20,000 |
| Net cost after grant (eligible homes) | $5,500 | -$2,200 | $9,500 |
Cesspools are disproportionately common on small lots in dense older neighborhoods near coastal areas - exactly the conditions that disqualify conventional septic systems. A small lot on Long Island may have insufficient setback distances for a conventional drain field, a water table 18 inches below the surface, and a perc rate that reflects decades of soil saturation. This typically means an innovative/alternative (IA) system with nitrogen removal capability is the only permitted option, which is why conversion costs often land in the $15,000-$25,000 range even before accounting for the cesspool decommissioning.
Up to $20,000 grant for eligible homeowners converting from a cesspool to an approved IA system. Income requirements apply (under $175,000 household income for some tiers). Application through Suffolk County DPW. Apply before installation - grants are not retroactive.
Low-interest loans through the Clean Water SRF for septic improvements. Can be combined with Suffolk County grants for low-income homeowners.
Many Massachusetts municipalities offer betterment loans for Title 5-required upgrades, typically at low interest rates spread over 5-20 years.
Loans up to $40,000 at 1% for low-income rural homeowners. Grants up to $10,000 for elderly homeowners who cannot repay a loan. Available nationwide including in designated rural areas of Long Island and coastal New England.