Is Williston, ND Tap Water Safe? Quality & Contaminants

What was found in Williston's water

The highest level seen across the city's suppliers, the EPA limit for each, and where the figure comes from.

Contaminant	Level vs EPA limit	Suppliers	Source
Fluoride	810 µg/L 20% of the EPA limit 4000 µg/L	1/5	SYR4
Nitrate-Nitrite	300 µg/L 3% of the EPA limit 10000 µg/L	1/5	SYR4
Copper	293 µg/L 23% of the EPA limit 1300 µg/L	4/5	SYR4
Lead	89.4 µg/L 596% of the EPA limit, in the worst sample — 15 µg/L	3/5	SYR4
Lithium	79 µg/L No EPA limit set	2/5	UCMR-5
TTHM	46.87 µg/L 59% of the EPA limit 80 µg/L	4/5	SYR4
Total Haloacetic Acids (HAA5)	40.2 µg/L 67% of the EPA limit 60 µg/L	4/5	SYR4
Chloroform	38.7 µg/L No EPA limit set	4/5	SYR4
Dichloroacetic Acid	28.3 µg/L No EPA limit set	4/5	SYR4
Barium	14.3 µg/L 0.7% of the EPA limit 2000 µg/L	1/5	SYR4
Bromodichloromethane	10.09 µg/L No EPA limit set	4/5	SYR4
Trichloroacetic Acid	7.54 µg/L No EPA limit set	4/5	SYR4
Monochloroacetic Acid	4.36 µg/L No EPA limit set	2/5	SYR4
Gross Alpha, Excl. Radon And U	3.9 pCi/L 26% of the EPA limit 15 pCi/L	1/5	SYR4
Dibromochloromethane	3.18 µg/L No EPA limit set	4/5	SYR4
Selenium	1.44 µg/L 2.9% of the EPA limit 50 µg/L	1/5	SYR4
Chromium	1.17 µg/L 1.2% of the EPA limit 100 µg/L	1/5	SYR4
Dibromoacetic Acid	1.14 µg/L No EPA limit set	3/5	SYR4
Combined Radium (-226 And -228)	0.7800 pCi/L 16% of the EPA limit 5 pCi/L	1/5	SYR4
Bromoform	0.2800 µg/L No EPA limit set	1/5	SYR4
Pentachlorophenol	0.0300 µg/L 3% of the EPA limit 1 µg/L	1/5	SYR4
Pfba	0.0063 µg/L No EPA limit set	1/5	UCMR-5
Lead	0.0 mg/L 0% of the EPA limit 0.0150 mg/L	4/5	LCR
Combined Uranium	-0.44 µg/L -1.5% of the EPA limit 30 µg/L	1/5	SYR4

Each bar shows the measured level as a share of the EPA limit: green is well under, amber is close to it, red is over. For lead and copper the limit applies to exactly the 90th-percentile figure shown, so red there means a real exceedance. For everything else the limit applies to a running annual average while the figure is the single worst sample on record — over 100% is worth reading, but is not by itself a violation. Formal violations are listed separately. These are the utilities' own EPA-reported results, not a city-wide average. A detection means the lab measured the substance — it isn't the same as exceeding a legal limit. Hover a source tag to see the EPA program and years behind each figure.

Water suppliers serving Williston

Supplier	Population served
WILLISTON CITY OF	26,426
NORTHWEST RURAL WATER DISTRICT	5,102
INSPIRE COMMUNITIES-SPRINGBROOK	300
PRAIRIE VIEW HOA	226
WESTERN AREA WATER SUPPLY AUTHORITY	0

Frequently asked questions about Williston tap water

Is Williston tap water safe to drink?

EPA testing detected 24 contaminants in the water serving Williston. A detection isn't the same as a violation — most detected levels are within federal limits. Check the level and source for each contaminant above, and your utility's annual Consumer Confidence Report for the official compliance status.

How many water suppliers serve Williston?

5 public water suppliers report drinking-water monitoring for Williston, North Dakota to the EPA. Each is listed above with its population served.

What contaminants are in Williston's water?

The contaminants EPA monitoring detected in Williston include Fluoride, Nitrate-Nitrite, Copper, Lead, Lithium. The full list, with the highest level found and the data source, is in the table above.

Where does this data come from?

Every figure is official EPA drinking-water monitoring — the Lead & Copper Rule, the UCMR-5 nationwide testing program, and the EPA Six-Year Review — not our own testing. Each number is labelled with its source and period.