PFAS in tap water, ZIP 19317 (Chester County and Delaware County)
1 of 3 water systems had PFAS-4 above our 0.5 ng/L benchmark at the latest sample. Highest: Aqua PA Main System, 24.5 ng/L. 3 had PFOA or PFOS above the 4 ng/L federal MCL in at least one sample.
3 community water systems report serving ZIP 19317 (Chester County and Delaware County, Pennsylvania) · 970,846 people served
Water systems serving ZIP 19317
| Water system | People served | PFAS-4 at the latest sample | Entry points | Latest sample |
|---|---|---|---|---|
| Aqua PA Main System reported by the system to EPA | 822,600 | 24.5 ng/L above the 2029 federal MCL | 19 | December 11, 2024 |
| Chester Water Authority reported by the system to EPA | 140,437 | below the 3 to 4 ng/L reporting limit above the 2029 federal MCL in an earlier sample | 1 | November 13, 2024 |
| Veolia Water Bethel reported by the system to EPA | 7,809 | below the 3 to 4 ng/L reporting limit above the 2029 federal MCL in an earlier sample | 4 | October 20, 2025 |
Not sure which one is yours? The systems report their own ZIP lists to EPA. Check your water bill or your utility's Consumer Confidence Report.
Where this ZIP is
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.