PFAS in tap water, Mercer County, New Jersey
2 of 5 water systems had PFAS-4 above our 0.5 ng/L benchmark at the latest sample. Highest: Aqua NJ - Hamilton Square, 32.2 ng/L. 2 had PFOA or PFOS above the 4 ng/L federal MCL in at least one sample.
5 community water systems · 295,183 people served · newest sample September 3, 2025
Water systems in Mercer County
| Water system | People served | PFAS-4 at the latest sample | Entry points | Latest sample |
|---|---|---|---|---|
| Trenton Water Works | 217,000 | below the 3 to 4 ng/L reporting limit | 1 | January 22, 2024 |
| Aqua NJ - Hamilton Square | 39,128 | 32.2 ng/L above the 2029 federal MCL | 5 | September 3, 2025 |
| East Windsor MUA | 25,000 | below the 3 to 4 ng/L reporting limit | 4 | September 17, 2024 |
| Aqua NJ - Lawrence | 8,655 | 12.3 ng/L above the 2029 federal MCL | 2 | July 15, 2025 |
| Hightstown Water Department | 5,400 | below the 3 to 4 ng/L reporting limit | 1 | July 14, 2025 |
| Pennington Shop-Rite non-transient non-community water system | 3,663 | monitored under UCMR 5, no page | ||
| Bear Tavern School non-transient non-community water system | 555 | monitored under UCMR 5, no page | ||
2 systems without a page are not a community water system (schools, workplaces, campgrounds). Nobody's home tap water.
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 Mercer 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.
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.