What was found in Centennial'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 |
|---|---|---|---|
| Nitrate | 6685 µg/L 67% of the EPA limit 10000 µg/L Highest in the city: JOINT WATER PURIFICATION PLANT · 0 people · 2019 | 2/4 | SYR4 |
| Nitrate-Nitrite | 1325 µg/L 13% of the EPA limit 10000 µg/L Highest in the city: ARAPAHOE CNTY WWWA · 31,000 people · 2015 | 2/4 | SYR4 |
| Fluoride | 1310 µg/L 33% of the EPA limit 4000 µg/L Highest in the city: ARAPAHOE CNTY WWWA · 31,000 people · 2019 | 2/4 | SYR4 |
| Barium | 291.1 µg/L 15% of the EPA limit 2000 µg/L Highest in the city: ARAPAHOE CNTY WWWA · 31,000 people · 2019 | 2/4 | SYR4 |
| TTHM | 50.55 µg/L 63% of the EPA limit 80 µg/L Highest in the city: JOINT WATER PURIFICATION PLANT · 0 people · 2019 | 2/4 | SYR4 |
| Combined Uranium | 37.4 µg/L 125% of the EPA limit, at the 95th percentile of samples — 30 µg/L Highest in the city: JOINT WATER PURIFICATION PLANT · 0 people · 2018 | 2/4 | SYR4 |
| Lithium | 23.2 µg/L No EPA limit set Highest in the city: ARAPAHOE CNTY WWWA · 31,000 people · 2023 | 1/4 | UCMR-5 |
| Bromoform | 18.36 µg/L No EPA limit set Highest in the city: ARAPAHOE CNTY WWWA · 31,000 people · 2019 | 2/4 | SYR4 |
| Selenium | 17.6 µg/L 35% of the EPA limit 50 µg/L Highest in the city: JOINT WATER PURIFICATION PLANT · 0 people · 2019 | 2/4 | SYR4 |
| Gross Alpha, Excl. Radon And U | 17.395 pCi/L 116% of the EPA limit, at the 95th percentile of samples — 15 pCi/L Highest in the city: JOINT WATER PURIFICATION PLANT · 0 people · 2018 | 2/4 | SYR4 |
| Dibromochloromethane | 17.04 µg/L No EPA limit set Highest in the city: ARAPAHOE CNTY WWWA · 31,000 people · 2019 | 2/4 | SYR4 |
| Total Haloacetic Acids (HAA5) | 12.026 µg/L 20% of the EPA limit 60 µg/L Highest in the city: ARAPAHOE CNTY WWWA · 31,000 people · 2019 | 1/4 | SYR4 |
| Bromodichloromethane | 9.96 µg/L No EPA limit set Highest in the city: ARAPAHOE CNTY WWWA · 31,000 people · 2019 | 2/4 | SYR4 |
| Chloroform | 7.57 µg/L No EPA limit set Highest in the city: ARAPAHOE CNTY WWWA · 31,000 people · 2019 | 1/4 | SYR4 |
| Arsenic | 6.95 µg/L 70% of the EPA limit 10 µg/L Highest in the city: ARAPAHOE CNTY WWWA · 31,000 people · 2019 | 2/4 | SYR4 |
| Dibromoacetic Acid | 6.74 µg/L No EPA limit set Highest in the city: ARAPAHOE CNTY WWWA · 31,000 people · 2019 | 1/4 | SYR4 |
| Combined Radium (-226 And -228) | 5.05 pCi/L 101% of the EPA limit, at the 95th percentile of samples — 5 pCi/L Highest in the city: ARAPAHOE CNTY WWWA · 31,000 people · 2019 | 2/4 | SYR4 |
| Dichloroacetic Acid | 3.985 µg/L No EPA limit set Highest in the city: ARAPAHOE CNTY WWWA · 31,000 people · 2019 | 1/4 | SYR4 |
| Trichloroacetic Acid | 2.18 µg/L No EPA limit set Highest in the city: ARAPAHOE CNTY WWWA · 31,000 people · 2019 | 1/4 | SYR4 |
| Di(2-ethylhexyl) Adipate | 1.4 µg/L 0.4% of the EPA limit 400 µg/L Highest in the city: ARAPAHOE CNTY WWWA · 31,000 people · 2019 | 1/4 | SYR4 |
| Di(2-ethylhexyl) Phthalate | 1.3 µg/L 22% of the EPA limit 6 µg/L Highest in the city: ARAPAHOE CNTY WWWA · 31,000 people · 2019 | 1/4 | SYR4 |
| Antimony, Total | 1.167 µg/L 19% of the EPA limit 6 µg/L Highest in the city: ARAPAHOE CNTY WWWA · 31,000 people · 2019 | 1/4 | SYR4 |
| Chromium | 0.2700 µg/L 0.3% of the EPA limit 100 µg/L Highest in the city: ARAPAHOE CNTY WWWA · 31,000 people · 2019 | 1/4 | SYR4 |
| Cadmium | 0.1162 µg/L 2.3% of the EPA limit 5 µg/L Highest in the city: ARAPAHOE CNTY WWWA · 31,000 people · 2019 | 1/4 | SYR4 |
| Thallium, Total | 0.0771 µg/L 3.9% of the EPA limit 2 µg/L Highest in the city: ARAPAHOE CNTY WWWA · 31,000 people · 2019 | 1/4 | SYR4 |
| Mercury | 0.0397 µg/L 2% of the EPA limit 2 µg/L Highest in the city: ARAPAHOE CNTY WWWA · 31,000 people · 2019 | 1/4 | SYR4 |
| Lead | 0.0090 mg/L 60% of the EPA limit 0.0150 mg/L Main supplier: SOUTHGATE WSD · 55,000 people · 2002 | 3/4 | LCR |
| Pfpea | 0.0079 µg/L No EPA limit set Highest in the city: ARAPAHOE CNTY WWWA · 31,000 people · 2023 | 1/4 | UCMR-5 |
| Pfhxa | 0.0068 µg/L No EPA limit set Highest in the city: ARAPAHOE CNTY WWWA · 31,000 people · 2023 | 1/4 | UCMR-5 |
| PFBS | 0.0061 µg/L No EPA limit set Highest in the city: ARAPAHOE CNTY WWWA · 31,000 people · 2023 | 1/4 | UCMR-5 |
| Pfba | 0.0055 µg/L No EPA limit set Highest in the city: ARAPAHOE CNTY WWWA · 31,000 people · 2023 | 1/4 | UCMR-5 |
| PFOA | 0.0046 µg/L No EPA limit set Highest in the city: ARAPAHOE CNTY WWWA · 31,000 people · 2023 | 1/4 | UCMR-5 |
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 Centennial
| Supplier | Population served |
|---|---|
| SOUTHGATE WSD | 55,000 |
| ARAPAHOE CNTY WWWA | 31,000 |
| WILLOWS WD | 19,000 |
| JOINT WATER PURIFICATION PLANT | 0 |
Frequently asked questions about Centennial tap water
Is Centennial tap water safe to drink?
EPA testing detected 32 contaminants in the water serving Centennial. 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 Centennial?
4 public water suppliers report drinking-water monitoring for Centennial, Colorado to the EPA. Each is listed above with its population served.
What contaminants are in Centennial's water?
The contaminants EPA monitoring detected in Centennial include Nitrate, Nitrate-Nitrite, Fluoride, 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.