Water filter installation in Long Island

What the water is like across Long Island

More than 1,500 public supply wells pump over 400 million gallons a day for roughly three million people. The two counties are organised very differently. Suffolk is largely one utility, the Suffolk County Water Authority. Nassau is the opposite: dozens of separate water districts and village systems, each with its own wells, its own treatment and its own annual report, so two houses a mile apart can be on different districts with different disinfectants. New York set maximum contaminant levels of 10 parts per trillion each for PFOA and PFOS and 1 part per billion for 1,4-dioxane, the first such limit in the United States, and several districts were granted deferrals on the compliance deadline because of treatment cost. The two problems need different equipment. Granular activated carbon handles PFOA and PFOS. 1,4-dioxane passes straight through carbon and needs advanced oxidation.

What this means locally

Private wells are the blind spot here and the reason a regional page cannot answer the question for everyone. Outside the public districts a substantial number of households draw their own water from the same sole source aquifer, and none of the monitoring that applies to a public supply applies to them. No agency samples a private well, no annual report describes it, no inventory records its service line. Given that the aquifer's documented problems are 1,4-dioxane and PFAS, and that neither is detectable by taste, smell or appearance, a private well owner here genuinely cannot know what they are drinking without paying for a test. The 2025 settlement with 3M directed 250 million dollars to more than twenty Long Island water districts, usable for operations and maintenance rather than construction alone, which helps public supply and does nothing for a private well. If you are on your own well on Long Island, testing for 1,4-dioxane and the PFAS group is the single most useful thing you can do, and it comes before any equipment decision.

Utilities we have researched here

2 separate utilities supply the researched towns in this region, and they do not all treat water the same way.

• Multiple Nassau County water districts and village systems
• Suffolk County Water Authority (SCWA)

What that means for equipment

• 2 draw at least part of the supply from groundwater. Groundwater is steadier through the year than surface water and usually harder, and it tends to bring iron and manganese rather than the seasonal taste changes a reservoir produces.
• 2 have a documented lead service line position. In every one of them the lead comes from the service line or the plumbing inside the building rather than from the supply, so the measurement that answers it is a first draw sample taken after water has stood overnight.
• 2 have a published PFAS position. Where treatment is warranted it is granular activated carbon or reverse osmosis certified to NSF/ANSI 58. Where the utility already treats for it at the plant, a household system adds nothing.

Towns we cover in Long Island

Each has its own page carrying the utility, the source water, the treatment and the lead position, with every figure attributed to a publisher and the year it refers to.

We serve 10 areas in Long Island in total. The 8 not linked above are covered through the nearest listed town, usually because they share its water system and a separate page would repeat the same facts under a different name.

The researched towns side by side

Every figure below is taken from the town page it links to, where it carries its publisher and the year it refers to. A blank means we hold no sourced figure for that town rather than that the value is zero.

Systems we install here

Installation and service across Long Island

Other regions in New York

Or read the New York hub for the state regulators, the PFAS and lead rules that apply across New York, and every area we cover there.