We read 24 results from Denver Water Board’s 2025 water quality report. No results over a legal limit; 2 above a health goal or guideline.
Serves about 1,287,000 people · Water system ID CO0116001 · Read the district’s 2025 report (opens in a new tab)
Open this district in the water lookupCompare with your own test results, see the district map and get matched filters.
Results from the 2025 report
Each number is copied from the district’s report and links to the page it’s printed on. Where the report lists several plants, wells or purchased water, the highest is shown.
| Contaminant | Result | Health goal | Legal limit | What it means |
|---|---|---|---|---|
| Lead90th percentile of 337 homes tested, 1 over the action level · Customer taps, Jan-Jun 2025 (337 samples), highest of 2 sources · 2025 report, page 13 | 4 ppb | 0.2 ppb | 15 ppb (action level) | Above the health goal20x the health goal |
| Total coliform bacteriahighest month · Distribution system · 2025 report, page 13 | 0.5 % positive | 0 % positive | 5 % positive | Above the health goalThe health goal is zero |
| Aluminumaverage · range 0.02 to 0.09 · printed as 31.4 ppb · Distribution system · 2025 report, page 14 | 0.03 ppm | — | 0.2 ppm guideline | Within the guideline |
| Bariumaverage · range 0.04 to 0.04 · printed as 40.1 ppb · Marston plant, highest of 3 sources · 2025 report, page 11 | 0.04 ppm | 2 ppm | 2 ppm | Below the health goal |
| Chlorideaverage · range 6.8 to 35 · printed as 24,000 ppb · Distribution system · 2025 report, page 14 | 24 ppm | — | 250 ppm guideline | Within the guideline |
| Chromium (total)average · range ND to 1.8 · Foothills plant, highest of 3 sources · 2025 report, page 10 | 0.5 ppb | None set | 100 ppb | Below the legal limit |
| Copper90th percentile of 337 homes tested, 0 over the action level · printed as 60 ppb · Customer taps, Jan-Jun 2025 (337 samples), highest of 2 sources · 2025 report, page 13 | 0.06 ppm | 0.3 ppm | 1.3 ppm (action level) | Below the health goal |
| Disinfection byproducts (HAA5)highest running annual average · range 7.2 to 26.7 · Distribution system · 2025 report, page 13 | 19.5 ppb | None set | 60 ppb | Below the legal limit |
| Disinfection byproducts (TTHM)highest running annual average · range 8.8 to 41.1 · Distribution system · 2025 report, page 13 | 35.5 ppb | None set | 80 ppb | Below the legal limit |
| Fluorideaverage · range 0.53 to 0.75 · printed as 619 ppb · Marston plant, highest of 3 sources · 2025 report, page 11 | 0.62 ppm | 1 ppm | 4 ppm | Below the health goal |
| Manganeseaverage · range ND to 0.03 · printed as 1.9 ppb · Distribution system · 2025 report, page 14 | 0.0019 ppm | — | 0.05 ppm guideline | Within the guideline |
| Mercuryaverage · range ND to 0.12 · Foothills plant · 2025 report, page 10 | Not detected | 1.2 ppb | 2 ppb | Not detected |
| Nitrate (as N)average · range ND to 0.18 · printed as 104 ppb · Foothills plant, highest of 3 sources · 2025 report, page 10 | 0.1 ppm | 10 ppm | 10 ppm | Below the health goal |
| PFOA (a PFAS)average · printed as BRL ppb · Entry points, all plants (UCMR 5) · 2025 report, page 15 | Not detected | 0.007 ppt | 4 ppt from 2029 | Not detected |
| PFOS (a PFAS)average · printed as BRL ppb · Entry points, all plants (UCMR 5) · 2025 report, page 15 | Not detected | 1 ppt | 4 ppt from 2029 | Not detected |
| Sulfateaverage · range 23 to 83 · printed as 58,300 ppb · Distribution system · 2025 report, page 14 | 58.3 ppm | — | 250 ppm guideline | Within the guideline |
| Turbidity (cloudiness)highest measured · Northwater plant, highest of 3 sources · 2025 report, page 12 | 0.17 NTU | None set | 1 NTU | Below the legal limit |
| Zincaverage · range ND to 0.01 · printed as 2.8 ppb · Distribution system · 2025 report, page 14 | 0.0028 ppm | — | 5 ppm guideline | Within the guideline |
| Alkalinityaverage · range 41 to 82 · printed as 65,037 ppb · Distribution system · 2025 report, page 14 | 65 ppm | None set | None | No health limit |
| Conductivityaverage · range 150 to 420 · Distribution system · 2025 report, page 14 | 338 µS/cm | None set | None | No health limit |
| Hardnessaverage · range 3.22 to 7.25 · Distribution system · 2025 report, page 14 | 6.14 gpg (105 ppm) | — | — | Moderately hard |
| Lithiumaverage · range 9 to 9.4 · sampled 2023 · Marston plant, highest of 2 sources · 2025 report, page 15 | 9.23 ppb | None set | None | No health limit |
| Nickelaverage · range ND to 1.6 · Foothills plant, highest of 2 sources · 2025 report, page 10 | 1 ppb | None set | None | No health limit |
| Sodiumaverage · range 19.1 to 27.2 · printed as 23,820 ppb · Marston plant, highest of 3 sources · 2025 report, page 11 | 23.8 ppm | None set | None | No health limit |
Utility results describe the whole system, measured where water enters the pipes, not your tap. Your home’s plumbing can add lead or copper.
EPA testing for PFAS and lithium
EPA’s own nationwide testing (UCMR 5) found these in Denver Water Board’s water between Mar 2023 and Apr 2025. These are EPA lab results, separate from the district’s report. Anything not listed was not detected.
- Lithium10.8 ppbFound in 5 of 15 samples · highest resultAbove EPA’s health reference level of 10 ppb (a guide, not a legal limit)
Source: EPA UCMR 5 occurrence data. The highest single result is shown; one high sample doesn’t mean every glass is that high.
What you can do
Nothing here is an emergency notice: if the district has a violation, it must tell customers directly. If you’d like to lower these at your tap, these are the treatments that remove them, and the catalog shows the models certified for each. Ranking is by certified removal; commissions never change the order.
Lead
Found: Lead
What removes it: Certified carbon block or RO.
Bacteria and viruses
Found: Total coliform bacteria
What removes it: UV purification (and tell your utility).
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