What was found in Denver's water
The level at the city's main supplier, the highest level anywhere in the city, the EPA limit for each, and where every figure comes from.
| Contaminant | Level vs EPA limit | Suppliers | Source |
|---|---|---|---|
| Fluoride | 803 µg/L 20% of the EPA limit 4000 µg/L Main supplier: DENVER WATER BOARD · 1,287,000 people · 2019 | 1/4 | SYR4 |
| Nitrate-Nitrite | 252 µg/L 2.5% of the EPA limit 10000 µg/L Main supplier: DENVER WATER BOARD · 1,287,000 people · 2019 | 1/4 | SYR4 |
| Nitrate | 250 µg/L 2.5% of the EPA limit 10000 µg/L Main supplier: DENVER WATER BOARD · 1,287,000 people · 2019 | 1/4 | SYR4 |
| Barium | 43.51 µg/L 2.2% of the EPA limit 2000 µg/L Main supplier: DENVER WATER BOARD · 1,287,000 people · 2019 | 1/4 | SYR4 |
| TTHM | 32.59 µg/L 41% of the EPA limit 80 µg/L Main supplier: DENVER WATER BOARD · 1,287,000 people · 2019 | 1/4 | SYR4 |
| Cyanide | 24.85 µg/L 12% of the EPA limit 200 µg/L Main supplier: DENVER WATER BOARD · 1,287,000 people · 2015 | 1/4 | SYR4 |
| Total Haloacetic Acids (HAA5) | 23 µg/L 38% of the EPA limit 60 µg/L Main supplier: DENVER WATER BOARD · 1,287,000 people · 2019 | 1/4 | SYR4 |
| Chloroform | 20.265 µg/L No EPA limit set Main supplier: DENVER WATER BOARD · 1,287,000 people · 2019 | 1/4 | SYR4 |
| Dichloroacetic Acid | 12.8 µg/L No EPA limit set Main supplier: DENVER WATER BOARD · 1,287,000 people · 2019 | 1/4 | SYR4 |
| Lithium | 10.8 µg/L No EPA limit set Main supplier: DENVER WATER BOARD · 1,287,000 people · 2025 | 1/4 | UCMR-5 |
| Bromodichloromethane | 8.9 µg/L No EPA limit set Main supplier: DENVER WATER BOARD · 1,287,000 people · 2019 | 1/4 | SYR4 |
| Trichloroacetic Acid | 6.855 µg/L No EPA limit set Main supplier: DENVER WATER BOARD · 1,287,000 people · 2019 | 1/4 | SYR4 |
| Combined Uranium | 5.775 µg/L 19% of the EPA limit 30 µg/L Main supplier: DENVER WATER BOARD · 1,287,000 people · 2019 | 1/4 | SYR4 |
| Selenium | 5.44 µg/L 11% of the EPA limit 50 µg/L Main supplier: DENVER WATER BOARD · 1,287,000 people · 2019 | 1/4 | SYR4 |
| Dibromochloromethane | 3.9 µg/L No EPA limit set Main supplier: DENVER WATER BOARD · 1,287,000 people · 2019 | 1/4 | SYR4 |
| Gross Beta Particle Activity | 3 pCi/L No EPA limit set Main supplier: DENVER WATER BOARD · 1,287,000 people · 2018 | 1/4 | SYR4 |
| Monochloroacetic Acid | 2.9 µg/L No EPA limit set Main supplier: DENVER WATER BOARD · 1,287,000 people · 2019 | 1/4 | SYR4 |
| Monobromoacetic Acid | 2.82 µg/L No EPA limit set Main supplier: DENVER WATER BOARD · 1,287,000 people · 2019 | 1/4 | SYR4 |
| Gross Alpha, Excl. Radon And U | 2 pCi/L 13% of the EPA limit 15 pCi/L Main supplier: DENVER WATER BOARD · 1,287,000 people · 2018 | 1/4 | SYR4 |
| Combined Radium (-226 And -228) | 1.95 pCi/L 39% of the EPA limit 5 pCi/L Main supplier: DENVER WATER BOARD · 1,287,000 people · 2014 | 1/4 | SYR4 |
| Chromium | 1.7 µg/L 1.7% of the EPA limit 100 µg/L Main supplier: DENVER WATER BOARD · 1,287,000 people · 2019 | 1/4 | SYR4 |
| Dibromoacetic Acid | 1.4 µg/L No EPA limit set Main supplier: DENVER WATER BOARD · 1,287,000 people · 2019 | 1/4 | SYR4 |
| Arsenic | 1.14 µg/L 11% of the EPA limit 10 µg/L Main supplier: DENVER WATER BOARD · 1,287,000 people · 2019 | 1/4 | SYR4 |
| Bromoform | 0.8350 µg/L No EPA limit set Main supplier: DENVER WATER BOARD · 1,287,000 people · 2019 | 1/4 | SYR4 |
| Carbon Tetrachloride | 0.4930 µg/L 9.9% of the EPA limit 5 µg/L Main supplier: DENVER WATER BOARD · 1,287,000 people · 2019 | 1/4 | SYR4 |
| Antimony, Total | 0.2285 µg/L 3.8% of the EPA limit 6 µg/L Main supplier: DENVER WATER BOARD · 1,287,000 people · 2019 | 1/4 | SYR4 |
| 2,4-D | 0.1000 µg/L 0.1% of the EPA limit 70 µg/L Main supplier: DENVER WATER BOARD · 1,287,000 people · 2019 | 1/4 | SYR4 |
| Cadmium | 0.0960 µg/L 1.9% of the EPA limit 5 µg/L Main supplier: DENVER WATER BOARD · 1,287,000 people · 2019 | 1/4 | SYR4 |
| Mercury | 0.0700 µg/L 3.5% of the EPA limit 2 µg/L Main supplier: DENVER WATER BOARD · 1,287,000 people · 2019 | 1/4 | SYR4 |
| Beryllium, Total | 0.0600 µg/L 1.5% of the EPA limit 4 µg/L Main supplier: DENVER WATER BOARD · 1,287,000 people · 2019 | 1/4 | SYR4 |
| Thallium, Total | 0.0600 µg/L 3% of the EPA limit 2 µg/L Main supplier: DENVER WATER BOARD · 1,287,000 people · 2019 | 1/4 | SYR4 |
| Lead | 0.0031 mg/L 21% of the EPA limit 0.0150 mg/L Main supplier: DENVER WATER BOARD · 1,287,000 people · 2025
Highest in the city: 0.0090 mg/L — CHERRY CREEK VALLEY WSD · 22,000 people · 2002 | 4/4 | 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 95th percentile of the
system's samples — 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 Denver
| Supplier | Population served |
|---|---|
| DENVER WATER BOARD | 1,287,000 |
| CHERRY CREEK VALLEY WSD | 22,000 |
| ADVENIR FRENCH QUARTER | 3,447 |
| GARDEN MEADOWS | 250 |
Frequently asked questions about Denver tap water
Is Denver tap water safe to drink?
EPA testing detected 32 contaminants in the water serving Denver. 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 Denver?
4 public water suppliers report drinking-water monitoring for Denver, Colorado to the EPA. Each is listed above with its population served.
What contaminants are in Denver's water?
The contaminants EPA monitoring detected in Denver include Fluoride, Nitrate-Nitrite, Nitrate, Barium, TTHM. The full list, with the level at the main supplier 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.