Is Boulder, CO Tap Water Safe? Quality & Contaminants

What was found in Boulder'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
Nitrate	3400 µg/L 34% of the EPA limit 10000 µg/L	5/10	SYR4
Fluoride	1910 µg/L 48% of the EPA limit 4000 µg/L	5/10	SYR4
Nitrate-Nitrite	1100 µg/L 11% of the EPA limit 10000 µg/L	2/10	SYR4
Total Haloacetic Acids (HAA5)	185.84 µg/L 310% of the EPA limit, in the worst sample — 60 µg/L	10/10	SYR4
TTHM	137.02 µg/L 171% of the EPA limit, in the worst sample — 80 µg/L	10/10	SYR4
Barium	119 µg/L 5.9% of the EPA limit 2000 µg/L	5/10	SYR4
Chloroform	60.2 µg/L No EPA limit set	9/10	SYR4
Trichloroacetic Acid	33.1 µg/L No EPA limit set	7/10	SYR4
Bromodichloromethane	23 µg/L No EPA limit set	9/10	SYR4
Dichloroacetic Acid	20.6 µg/L No EPA limit set	8/10	SYR4
Dibromochloromethane	18 µg/L No EPA limit set	9/10	SYR4
Bromoform	7.3 µg/L No EPA limit set	6/10	SYR4
Gross Alpha, Excl. Radon And U	5.9 pCi/L 39% of the EPA limit 15 pCi/L	4/10	SYR4
Combined Uranium	5 µg/L 17% of the EPA limit 30 µg/L	1/10	SYR4
Dibromoacetic Acid	4.5 µg/L No EPA limit set	6/10	SYR4
Selenium	3.5 µg/L 7% of the EPA limit 50 µg/L	3/10	SYR4
Tetrachloroethylene	3.1 µg/L 62% of the EPA limit 5 µg/L	1/10	SYR4
Chromium	3 µg/L 3% of the EPA limit 100 µg/L	5/10	SYR4
Monochloroacetic Acid	2.5 µg/L No EPA limit set	6/10	SYR4
Combined Radium (-226 And -228)	2 pCi/L 40% of the EPA limit 5 pCi/L	3/10	SYR4
Monobromoacetic Acid	1.2 µg/L No EPA limit set	2/10	SYR4
Arsenic	1 µg/L 10% of the EPA limit 10 µg/L	1/10	SYR4
Lead	0.0040 mg/L 27% of the EPA limit 0.0150 mg/L	9/10	LCR

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 Boulder

Supplier	Population served
BOULDER CITY OF	166,080
PINE BROOK HILLS WD	1,100
MILE HI WATER INC HAULER	1,000
BASELINE WD	820
VISTA VILLAGE MHP	750
SHANNON WSD	450
EAST BOULDER COUNTY WD	300
LEFTHAND WSD LAKE PINES	250
SANS SOUCI COOPERATIVE	150
SPRING VALLEY MUTUAL WA	100

Frequently asked questions about Boulder tap water

Is Boulder tap water safe to drink?

EPA testing detected 23 contaminants in the water serving Boulder. 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 Boulder?

10 public water suppliers report drinking-water monitoring for Boulder, Colorado to the EPA. Each is listed above with its population served.

What contaminants are in Boulder's water?

The contaminants EPA monitoring detected in Boulder include Nitrate, Fluoride, Nitrate-Nitrite, Total Haloacetic Acids (HAA5), TTHM. 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.