PFAS in tap water, Montgomery County, Pennsylvania
12 of 15 water systems had PFAS-4 above our 0.5 ng/L benchmark at the latest sample. Highest: Collegeville Trappe Joint PWD, 253.1 ng/L. 13 had PFOA or PFOS above the 4 ng/L federal MCL in at least one sample.
15 community water systems · 1,219,993 people served · newest sample December 9, 2025
Water systems in Montgomery County
| Water system | People served | PFAS-4 at the latest sample | Entry points | Latest sample |
|---|---|---|---|---|
| Aqua PA Main System | 822,600 | 24.5 ng/L above the 2029 federal MCL | 19 | December 11, 2024 |
| North Penn Water Authority | 91,941 | 5.1 ng/L above the 2029 federal MCL | 5 | January 14, 2025 |
| PA American Norristown | 88,885 | below the 3 to 4 ng/L reporting limit | 1 | October 9, 2024 |
| North Wales Water Authority | 72,496 | 12.5 ng/L above the 2029 federal MCL | 7 | May 14, 2025 |
| Pottstown Borough Water Auth | 36,000 | below the 3 to 4 ng/L reporting limit | 1 | June 18, 2025 |
| Horsham Water&sewer Authority | 26,000 | 61.9 ng/L above the 2029 federal MCL | 11 | August 18, 2025 |
| Ambler Boro Water Dept | 20,000 | 38.8 ng/L above the 2029 federal MCL | 9 | May 13, 2025 |
| Aqua PA Hatboro | 12,901 | 38 ng/L above the 2029 federal MCL | 3 | October 16, 2024 |
| Aqua PA Superior Main System | 11,400 | 15.8 ng/L above the 2029 federal MCL | 8 | February 19, 2025 |
| Collegeville Trappe Joint PWD | 8,470 | 253.1 ng/L above the 2029 federal MCL | 7 | September 20, 2023 |
| PA American Audubon | 8,200 | 71.3 ng/L above the 2029 federal MCL | 8 | October 16, 2024 |
| Telford Borough Authority | 7,700 | 32 ng/L above the 2029 federal MCL | 7 | December 8, 2025 |
| Schwenksville Borough Auth | 5,200 | 12.6 ng/L above the 2029 federal MCL | 4 | January 17, 2024 |
| Upper Hanover Water Authority | 4,600 | below the 3 to 4 ng/L reporting limit above the 2029 federal MCL in an earlier sample | 4 | December 9, 2025 |
| Aqua PA Perkiomen Township | 3,600 | 18.2 ng/L above the 2029 federal MCL | 5 | July 8, 2024 |
| Merck and CO INC non-transient non-community water system | 8,550 | monitored under UCMR 5, no page | ||
| Radisson Valley Forge Hotel non-transient non-community water system | 3,500 | 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.
ZIP codes in Montgomery 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.
- 18041
- 18070
- 18073
- 18074
- 18076
- 18914
- 18915
- 18936
- 18964
- 18969
- 19001
- 19002
- 19003
- 19004
- 19006
- 19009
- 19012
- 19025
- 19027
- 19031
- 19034
- 19035
- 19038
- 19040
- 19041
- 19044
- 19046
- 19066
- 19072
- 19075
- 19083
- 19085
- 19087
- 19090
- 19095
- 19096
- 19118
- 19128
- 19401
- 19403
- 19405
- 19406
- 19422
- 19426
- 19428
- 19436
- 19437
- 19438
- 19440
- 19444
- 19446
- 19454
- 19460
- 19462
- 19464
- 19468
- 19473
- 19474
- 19477
- 19490
- 19492
- 19505
- 19512
- 19525
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.