Tap Water Quality Report
Tap water quality in BOULDER, Colorado
Tap water in BOULDER, Colorado receives a grade of C (79/100) from TapWaterSafety.org. It's served by BOULDER CITY OF. The most significant water quality concerns are: Haloacetic acids (HAA9) significantly above health guideline; Haloacetic acids (HAA5) significantly above health guideline; Total trihalomethanes (TTHMs) significantly above health guideline. Data sources: EPA SDWIS, EPA ECHO, EWG Tap Water Database.
What's in BOULDER's tap water
Top water quality concerns identified by the EPA and Environmental Working Group across the utility serving BOULDER.
Haloacetic acids (HAA9) significantly above health guideline
Moderate concernHaloacetic acids (HAA9) detected at 30.6 ppb, 509x above the EWG health guideline of 0.06 ppb.
Haloacetic acids (HAA5) significantly above health guideline
Moderate concernHaloacetic acids (HAA5) detected at 25.9 ppb, 259x above the EWG health guideline of 0.1 ppb.
Total trihalomethanes (TTHMs) significantly above health guideline
Moderate concernTotal trihalomethanes (TTHMs) detected at 29.6 ppb, 198x above the EWG health guideline of 0.15 ppb.
EPA compliance record
Official U.S. EPA records for BOULDER CITY OF (system ID CO0107152) for the last 3 years. Checked 2026-10-07.
| Rule | Type | Since | Status |
|---|---|---|---|
| Interim and Long Term 1 Enhanced Surface Water Treatment Rule | Missed testing or reporting | 10/01/2024 | Resolved |
Source: U.S. EPA Enforcement and Compliance History Online (ECHO), from the Safe Drinking Water Information System. See EPA's full report.
Recommended filters for BOULDER
Filters matched to the specific contaminants in BOULDER's water supply.
Carbon filter certified for VOCs (NSF/ANSI 53)
$180-$599Activated carbon is effective for disinfection byproducts. Look for NSF/ANSI 53 VOC reduction.
Disclosure: TapWaterSafety earns a commission from purchases made through these links. This does not influence our scoring methodology or filter selection.
All contaminants detected in BOULDER's tap water
Every contaminant identified, compared side-by-side against US EPA legal limits, the EU Drinking Water Directive (2020/2184), WHO Guidelines, and California's Public Health Goal. Why we show multiple standards →
| Contaminant | Detected | EWG US health-based |
EPA US legal |
EU DWD Europe |
WHO global |
CA PHG strictest US |
Tested sample year |
Status |
|---|---|---|---|---|---|---|---|---|
| Haloacetic acids (HAA9) Disinfection byproduct |
30.6 ppb | 0.06 | — | — | — | — | — | 509× over |
| Haloacetic acids (HAA5) Disinfection byproduct |
25.9 ppb | 0.1 | 60.0 | 60 | — | — | — | 259× over |
| Total trihalomethanes (TTHMs) Disinfection byproduct |
29.6 ppb | 0.15 | 80.0 | 100 | — | — | — | 198× over |
| Trichloroacetic acid Disinfection byproduct |
13.4 ppb | 0.1 | — | — | — | — | — | 134× over |
| Chloroform Disinfection byproduct |
27.4 ppb | 0.4 | — | — | — | — | — | 69× over |
| Dichloroacetic acid Disinfection byproduct |
12.3 ppb | 0.2 | — | — | — | — | — | 62× over |
| Bromodichloromethane Disinfection byproduct |
2.17 ppb | 0.06 | — | — | — | — | — | 36× over |
| Chromium (hexavalent) Heavy metal |
0.171 ppb | 0.02 | — | — | — | — | — | 8.5× over |
| Chlorate Disinfection byproduct |
115.8 ppb | 210.0 | — | — | — | — | — | Below guideline |
| Dibromochloromethane Disinfection byproduct |
0.0292 ppb | 0.1 | — | — | — | — | — | Below guideline |
| Nitrate Inorganic |
0.0167 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | Below guideline |
| Barium Heavy metal |
11.3 ppb | 700.0 | 2000.0 | — | 1300 | 2000 | — | Below guideline |
| Vanadium Other |
0.179 ppb | 21.0 | — | — | — | — | — | Below guideline |
| Molybdenum Other |
0.2 ppb | 40.0 | — | — | — | — | — | Below guideline |
| Manganese Heavy metal |
0.239 ppb | 100.0 | — | 50 | 80 | — | — | Below guideline |
| Monochloroacetic acid Disinfection byproduct |
0.11 ppb | 53.0 | — | — | — | — | — | Below guideline |
| Strontium Radiological |
0.119 ppb | 1500.0 | — | — | — | — | — | Below guideline |
| Chromium (total) Heavy metal |
0.167 ppb | — | 100.0 | — | — | — | — | Below guideline |
| Fluoride Inorganic |
0.618 ppm | — | 4.0 | 1.5 | 1.5 | — | — | Below guideline |
| Testosterone Other |
0.016 ppt | — | — | — | — | — | — | Below guideline |
All values in the unit of the detected level. Red cells indicate the detected level exceeds that standard. Some contaminants have limits in some jurisdictions but not others (shown as —). The "Tested" column shows the year each contaminant sample was collected.
Sources: US EPA, EU Drinking Water Directive 2020/2184, WHO Guidelines, California OEHHA PHGs, EWG Tap Water Database.
Treatment plant contact info
For service issues, water quality concerns, or to request a Consumer Confidence Report from BOULDER CITY OF.