PFAS in tap water, Suffolk County, New York
2 of 10 water systems had PFAS-4 above our 0.5 ng/L benchmark at the latest sample. Highest: Suffolk County Water Authority, 29.1 ng/L. 3 had PFOA or PFOS above the 4 ng/L federal MCL in at least one sample.
10 community water systems · 1,344,004 people served · newest sample December 8, 2025
Water systems in Suffolk County
| Water system | People served | PFAS-4 at the latest sample | Entry points | Latest sample |
|---|---|---|---|---|
| Suffolk County Water Authority | 1,100,000 | 29.1 ng/L above the 2029 federal MCL | 242 | September 29, 2025 |
| South Huntington Water District | 81,760 | below the 3 to 4 ng/L reporting limit | 11 | April 15, 2025 |
| Greenlawn Water District | 42,000 | 3.2 ng/L | 12 | August 14, 2024 |
| Riverhead Water District | 35,000 | below the 3 to 4 ng/L reporting limit above the 2029 federal MCL in an earlier sample | 10 | May 3, 2024 |
| Dix Hills Water District | 34,522 | below the 3 to 4 ng/L reporting limit | 8 | December 8, 2025 |
| Smithtown Water District | 19,635 | below the 3 to 4 ng/L reporting limit | 1 | August 12, 2025 |
| Hampton Bays Water District | 12,500 | below the 3 to 4 ng/L reporting limit | 5 | July 30, 2024 |
| St James Water District | 10,587 | below the 3 to 4 ng/L reporting limit above the 2029 federal MCL in an earlier sample | 1 | February 3, 2025 |
| Ocean Beach Water District | 4,500 | below the 3 to 4 ng/L reporting limit | 2 | August 20, 2024 |
| Brookhaven National Laboratory | 3,500 | below the 3 to 4 ng/L reporting limit | 4 | August 11, 2025 |
Not sure which one is yours? The systems report their own service areas to EPA. Check your water bill or your utility's Consumer Confidence Report.
Cities and towns
ZIP codes in Suffolk County
Census ZIP code tabulation areas that overlap the county. A ZIP served by one system opens that system's page; a ZIP shared by several systems lists them.
- 11701
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How to read these numbers
We compare PFAS-4 (PFOA + PFOS + PFNA + PFHxS) with this site's 0.5 ng/L benchmark, the same line as on the European pages. UCMR 5 reporting limits are 3 to 4 ng/L. So any quantified PFAS-4 compound is above the benchmark, and a clean result reads "below the 3 to 4 ng/L reporting limit", never zero. The US legal limit is the 4 ng/L federal MCL for PFOA and PFOS, which systems must meet from April 26, 2029 ("above the 2029 federal MCL").
EPA: "UCMR 5 results do not indicate compliance or noncompliance with the PFAS drinking water standards". Samples are taken where water enters the distribution system, not at your tap. A system may have changed sources or added treatment since. Source: U.S. Environmental Protection Agency (EPA), Office of Water, PFAS National Primary Drinking Water Regulation (NPDWR). Regulation details retrieved September 19, 2026. Every system page tracks the 2029 compliance date and the proposed rescission of the PFHxS, PFNA, HFPO-DA and Hazard Index limits.
This site is a data project, not an official source. If in doubt, check with your water supplier or local authority.