iVerify · PFAS Report

Extreme PFAS in U.S. Drinking Water

Public water systems far over the federal limit · Generated June 8, 2026 · Source: EPA UCMR 5

What this report shows

Two "forever chemicals," PFOA and PFOS, are now limited in drinking water by the U.S. EPA. The federal limit is 4 parts per trillion (ppt) for each. A part per trillion is a tiny amount — about one drop in a few hundred swimming pools — but these chemicals are harmful at very low levels, so the limit is strict.

This report focuses on the extreme systems: public water systems testing at 10 times the limit or more (40 ppt or higher). These systems are legally over the limit and must lower their PFAS, which makes them the most urgent places for treatment.

1,141

U.S. systems over the 4 ppt limit

Extreme systems (10×+ over)

Of those, drawing from groundwater

86×

Worst system (Nashville, Town Of, NC)

Why it matters: Of the 1,141 systems nationwide that test over the federal limit, these 27 are the worst. Each one serves real people water that exceeds the federal safety standard by at least ten times, and each is required to bring those levels down.

Where they are: CA (4), FL (4), PA (3), NY (3), WV (2), AZ (2), NC (1), WA (1), GU (1), MS (1), MA (1), MD (1), AK (1), GA (1), NJ (1).

The 27 extreme systems

Ranked by the worst of their two readings. "× over" is how many times higher the system tests than the 4 ppt limit.

#	Water system	State	Size	Source	PFOA (ppt)	PFOS (ppt)	× over
1	Nashville, Town Of	NC	Small	Groundwater	5.775	345.0	86.2×
2	Potrero Elementary School	CA	Small	Groundwater	181.4	57.15	45.4×
3	Artondale Water System	WA	Small	Groundwater	6.3	153.6	38.4×
4	Running Springs Water District	CA	Small	Groundwater	11.7	131.0	32.8×
5	Emmaus Borough Public Water	PA	Large	Groundwater	19.5	127.0	31.8×
6	New Martinsville	WV	Small	Groundwater	8.0	121.8	30.4×
7	Pequenakonck Elementary School	NY	Small	Groundwater	111.5	10.0	27.9×
8	Yeshiva Farm Settlement	NY	Small	GW/surface-influenced	24.95	94.45	23.6×
9	Lubeck Psd	WV	Large	Groundwater	89.75	0.0	22.4×
10	Orangewood Water System	FL	Small	Groundwater	26.45	78.05	19.5×
11	Gwa Northern Water System	GU	Large	Groundwater	13.4	67.5	16.9×
12	Tempe City Of	AZ	Large	Groundwater	37.95	55.15	13.8×
13	Liberty Utilities - Bellflower-Norwalk	CA	Large	Surface water	15.5	55.0	13.8×
14	Audubon Water Company	PA	Small	Groundwater	28.95	54.1	13.5×
15	Somers Town House/Hall	NY	Small	Groundwater	20.4	53.35	13.3×
16	City Of Oxford	MS	Large	Groundwater	4.35	52.95	13.2×
17	Caernarvon Twp Auth	PA	Small	Groundwater	51.8	0.0	12.9×
18	Raynham Center Water District	MA	Large	Groundwater	48.65	0.0	12.2×
19	Montebello Land & Water Co.	CA	Large	Groundwater	14.0	46.5	11.6×
20	Fkaa J. Robert Dean W.T.P.	FL	Large	Groundwater	9.1	46.15	11.5×
21	North Miami, City Of	FL	Large	Groundwater	12.0	44.5	11.1×
22	Town Of Thurmont	MD	Small	GW/surface-influenced	14.0	44.5	11.1×
23	Lake Panasoffkee Water Assn 2Wps	FL	Small	Groundwater	6.4	44.1	11.0×
24	Barrow Utilities & Elec. Coop., Inc. (Bu	AK	Small	Surface water	0.0	44.05	11.0×
25	Augusta-Richmond Co Ws	GA	Large	Surface water	26.6	43.65	10.9×
26	Verona Water Department	NJ	Large	Surface water	42.3	12.2	10.6×
27	Liberty Water Rio Rico	AZ	Large	Groundwater	7.95	40.45	10.1×