Is Boulder, CO tap water safe?
Supplied by City of Boulder · serves 166,080 people (31,959 connections) · Surface water · EPA ID CO0107152
Data: U.S. EPA · How we read the data · How we check it
Most of Boulder gets its water from City of Boulder. Parts of the city are served by 2 smaller systems: Left Hand Water District (20,280 people), Vista Village MHP (750 people). Your water bill names your system.
Summary
No federal limits exceeded in EPA data.
- PFAS
- Not detectedNone of 29 PFAS found above EPA's reporting limits in 8 samples (2023–2025).
- Lead
- Below action level2 ppb (parts per billion) at the 90th percentile: 9 in 10 homes sampled were at or below it. Action level 15 ppb, falling to 10 ppb in Nov 2027. Monitoring period ending Dec 2025. Your home's pipes can make yours higher.
- Violations
- Resolved2 health-based violations since 2016, most recently Jul 2017.
- Built before 1986, or not sure what your service line is made of? Check your service line and test your tap. Utility data can't show your pipes.
- Want to reduce what was found? Filters for these results.
- Tested your own tap? Compare your result with these numbers. Moving? Compare this system with another.
- Read City of Boulder's annual water quality report (Consumer Confidence Report). It lists every regulated contaminant tested and is usually on the utility's website or mailed with your bill, and you can also request it at (720) 564-2320. EPA: how to find it.
PFAS (“forever chemicals”)
EPA UCMR 5: 2 entry points tested Feb 2023 to Nov 2023. "Average" is the highest entry-point average (non-detects counted as zero), the way EPA compares UCMR 5 results to the limits. ppt = parts per trillion. These results do not determine compliance.
| Contaminant | Highest average |
|---|---|
| PFOA Not detected Limit 4 ppt | – |
| PFOS Not detected Limit 4 ppt | – |
| PFHxS Not detected Limit 10 ppt | – |
| PFNA Not detected Limit 10 ppt | – |
| HFPO-DA (GenX) Not detected Limit 10 ppt | – |
| Hazard Index (a combined score for PFHxS, PFNA, GenX and PFBS, where above 1 is over the limit) Not detected Limit 1 | – |
| PFBS Not detected Guideline 2,000 ppt | – |
| PFBA Not detected Guideline 6,000 ppt | – |
| PFHxA Not detected Guideline 3,000 ppt | – |
29 PFAS tested, 0 detected at least once. "Not detected" means below EPA's reporting limit (about 2 to 20 ppt depending on the chemical), not proven zero. PFAS not listed were not detected. The limits for PFHxS, PFNA, GenX and the Hazard Index were proposed for rescission in May 2026. That proposal is not final. Systems have until 2029 to meet the limits.
Lithium
Not detected in 8 samples (reporting limit 9 ppb). About lithium.
Lead and copper
Latest 90th percentile: 2 ppb lead (Jan 2023 – Dec 2025). Below action level
Highest since 2016: 3.6 ppb (Dec 2017).
| Monitoring period | Lead (90th pct.) |
|---|---|
| Jan 2023 – Dec 2025 | 2 ppb |
| Jan 2021 – Dec 2021 | 1.7 ppb |
| Jan 2020 – Dec 2020 | 1.9 ppb |
Earlier results (9)
| Jan 2019 – Dec 2019 | 1.6 ppb |
| Jan 2018 – Dec 2018 | 2 ppb |
| Jan 2017 – Dec 2017 | 3.6 ppb |
| Jan 2014 – Dec 2016 | 2.1 ppb |
| Jan 2011 – Dec 2013 | 2 ppb |
| Jan 2008 – Dec 2010 | 3.05 ppb |
| Jan 2005 – Dec 2007 | 2.7 ppb |
| Jan 2002 – Dec 2004 | 6 ppb |
| Jan 1999 – Dec 1999 | 4 ppb |
Lead comes from pipes and fixtures, not the source water, so it varies home to home. The 90th percentile means 9 in 10 sampled homes were at or below it. More on lead.
Violations
| When | What happened |
|---|---|
| Apr 2017 – Jul 2017 2 times | The running annual average for Total Haloacetic Acids (HAA5) was above the legal limit. EPA record: Total Haloacetic Acids (HAA5) · Maximum Contaminant Level Violation, Average · measured 0.061 mg/l (limit 0.060 mg/L) Resolved |
Health-based violations mean a contaminant exceeded a limit or a required treatment step was missed. Monitoring and reporting violations mean required tests or reports were late or missing, so the water's quality during that time is unknown. The total includes every violation in EPA's records, most of them paperwork.
Earlier EPA testing (2013–2020)
| Contaminant | Highest | Guideline |
|---|---|---|
| Manganese | 0.51 ppb | 300 ppb |
| Chromium-6 | 0.34 ppb | – |
| Strontium | 0.34 ppm | 1.5 ppm |
| Molybdenum | 1.7 ppb | 40 ppb |
| Vanadium | 0.3 ppb | 21 ppb |
| Chlorate | 250 ppb | 210 ppb |
Where it serves
Boulder
ZIP codes the system reported serving: 80301, 80302, 80303, 80304, 80305, 80310
Nearby utilities
- County of Broomfield City and Broomfield · 12 mi
- City of Longmont Longmont · 13 mi
- City of Westminster Westminster · 14 mi
- City of Arvada Arvada · 14 mi
- City of Thornton Thornton · 18 mi
- Todd Creek Village Metropolitan District Thornton · 18 mi · PFAS above limit
Questions
Is Boulder tap water safe to drink?
Most of Boulder gets its water from City of Boulder. City of Boulder had 2 health-based violations since 2016, all since resolved. EPA testing found no PFAS above the federal limits. Federal data can't tell you about your own pipes: lead comes from service lines and plumbing, so test your tap if your home was built before 1986. For the official word, read the utility's annual Consumer Confidence Report.
Does Boulder water have PFAS?
EPA tested City of Boulder for 29 PFAS between Feb 2023 and Nov 2023 and none were detected above the reporting limits (about 2 to 20 ppt depending on the chemical).
What is the lead level in Boulder water?
The most recent 90th-percentile lead result for City of Boulder is 2 ppb, for the period ending Dec 2025. The federal action level is 15 ppb, falling to 10 ppb in November 2027. The 90th percentile means 9 in 10 homes sampled were at or below this number. Individual homes can be higher.
Check these numbers yourself
Every figure on this page comes from public EPA records. You don't have to take our word for it:
- EPA's own report for CO0107152: violations, enforcement and inspections, straight from EPA.
- EPA UCMR 5 data: the PFAS and lithium results (search the file for PWSID CO0107152).
- EPA SDWIS download: the lead results, population and violation records we use.
- The utility's annual water quality report (Consumer Confidence Report): ask City of Boulder at (720) 564-2320, or see EPA's guide to finding it.
Found something that doesn't match? Tell us and we'll check it against EPA's records. How we check our data.
Source: U.S. EPA drinking water records and PFAS testing (UCMR 5). How we read the data.