Water Quality in Boulder, CO: 192 Violations — Grade C
Grade C · Score 62/100 · 5 water systems · Updated 2026-05-03
Boulder's water has moderate compliance issues. Residents in affected areas should consider filtration.
Data: EPA Safe Drinking Water Information System (SDWIS) Last verified: 2026-05-03
Compliance records maintained by the EPA for Boulder, CO log 192 violations — accumulated reportable events drawn from every local utility in the SDWIS national tracking system.
Water Quality Map: Boulder, CO
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Water Quality by ZIP Code in Boulder
Water quality varies across Boulder's 16 ZIP codes. Check your specific ZIP for detailed contaminant data.
| ZIP Code | Grade | Score | Violations | Health | |
|---|---|---|---|---|---|
| 80302 | D | 53 | 12 | 2 | View report → |
| 80303 | D | 53 | 12 | 2 | View report → |
| 80304 | D | 53 | 12 | 2 | View report → |
| 80301 | C | 58 | 12 | 2 | View report → |
| 80305 | C | 58 | 12 | 2 | View report → |
| 80307 | C | 64 | 12 | 2 | View report → |
| 80309 | C | 64 | 12 | 2 | View report → |
| 80310 | C | 64 | 12 | 2 | View report → |
| 80314 | C | 64 | 12 | 2 | View report → |
| 80321 | C | 64 | 12 | 2 | View report → |
| 80322 | C | 64 | 12 | 2 | View report → |
| 80323 | C | 64 | 12 | 2 | View report → |
| 80328 | C | 64 | 12 | 2 | View report → |
| 80329 | C | 64 | 12 | 2 | View report → |
| 80306 | C | 68 | 12 | 2 | View report → |
Violation Trend
EPA violations recorded for water systems serving Boulder.
Water Quality Overview
Boulder, Colorado receives a water quality grade of C with an overall score of 62 out of 100, based on EPA compliance data from the Safe Drinking Water Information System (SDWIS).
The 5 water systems serving Boulder have accumulated 192 EPA violations, including 32 health-based violations. These violations are tracked across 16 ZIP codes serving approximately 169,750 people.
What Grade C Means
A grade of C indicates moderate compliance issues. Boulder's water systems have some violations that warrant attention. While the water may still be safe for most people, residents in affected ZIP codes should consider additional testing or filtration.
Lead Levels
The average 90th percentile lead level across Boulder water systems is 0.0020 mg/L — within EPA limits. No ZIP codes exceed the EPA lead action level.
With 67% of homes built before 1986, Boulder has a higher-than-average risk of lead from older plumbing. Lead solder was banned in 1986, and homes built before this date may have lead in pipes, solder joints, or fixtures.
Radon Risk
Boulder is in EPA Radon Zone 1 (High risk). The EPA recommends all homes in Zone 1 areas be tested for radon. Radon is the second leading cause of lung cancer after smoking.
Water Systems Serving Boulder
Boulder is served by 5 community water systems regulated under the Safe Drinking Water Act. These systems collectively serve approximately 169,750 people across 16 ZIP codes.
Each water system is identified by a Public Water System ID (PWSID) and is required to:
- Test for over 90 regulated contaminants on a regular schedule
- Report results to the EPA and state regulators
- Issue an annual Consumer Confidence Report (CCR) to all customers
- Take corrective action when violations occur
The EPA has taken 160 enforcement actions against water systems serving Boulder. Enforcement actions range from informal compliance assistance to formal orders and penalties.
How to Check Your Water in Boulder
Enter your ZIP code on ZipCheckup to see your specific water system data, including contaminant levels, violation history, and safety scores
Request your CCR — your water utility must provide an annual Consumer Confidence Report with detailed test results for all monitored contaminants
Get a home test — certified kits cost $20–$50 and test for lead, bacteria, and common contaminants. Professional lab tests ($150–$400) cover a broader panel
Consider filtration — NSF-certified filters can remove specific contaminants. Reverse osmosis removes the broadest range; activated carbon is effective for chlorine and many organics
Check for advisories — monitor your local utility website and local news for boil water advisories or system alerts
Contaminants Detected in Boulder Water Systems
The following contaminants have been detected or caused violations across Boulder's water systems:
| Contaminant | Category | MCL | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|---|
| Lead and Copper Rule | Treatment Technique | N/A | 96 | 16 | No |
| Surface Water Treatment Rule | Treatment Technique | N/A | 32 | 16 | No |
| Chlorine residual | Disinfectant | 4 mg/L | 32 | 16 | Yes |
| E. coli | Microbiological | N/A | 16 | 16 | No |
| Fecal Coliform | Microbiological | N/A | 16 | 16 | No |
MCL = Maximum Contaminant Level (EPA enforceable standard). Health-based violations indicate levels that may pose direct health risks.
Violation Trend Over Time
Year-by-year EPA violations recorded for water systems serving Boulder:
| Year | Total Violations | Health-Based |
|---|---|---|
| 2021 | 16 | 16 |
| 2022 | 16 | 16 |
Violation counts have remained stable over the observed period.
EPA Enforcement History
The EPA and state regulators have taken 10 enforcement actions against water systems serving Boulder. Recent actions:
| Date | Action Type |
|---|---|
| 2025-09-03 | State Informal Action |
| 2025-08-25 | State Order Extension |
| 2025-08-14 | State Informal Action |
| 2025-08-14 | State Informal Enforcement |
| 2025-07-22 | State Informal Action |
| 2025-07-22 | State Informal Enforcement |
| 2025-07-17 | State Informal Action |
| 2025-07-17 | State Informal Enforcement |
| 2025-07-15 | State Informal Action |
| 2025-07-15 | State Informal Enforcement |
Enforcement actions range from informal compliance assistance to formal orders and penalties. The most recent action was on 2025-09-03.
Boulder vs. Nearby Colorado Cities
How Boulder's water quality compares to similar cities in Colorado:
| City | Grade | Violations | Systems | Population |
|---|---|---|---|---|
| Boulder | C | 192 | 5 | 169,750 |
| Arvada | C | 35 | 3 | 173,420 |
| Eldorado Springs | D | 0 | 1 | 166,080 |
| Bellvue | D | 0 | 1 | 179,901 |
Water Quality by ZIP Code in Boulder
Water quality varies across Boulder's ZIP codes. The table below shows the worst-scoring and best-scoring areas:
| ZIP Code | Score | Grade | Violations | Health-Based |
|---|---|---|---|---|
| 80302 | 53 | D | 12 | 2 |
| 80303 | 53 | D | 12 | 2 |
| 80304 | 53 | D | 12 | 2 |
| 80301 | 58 | C | 12 | 2 |
| 80305 | 58 | C | 12 | 2 |
| 80307 | 64 | C | 12 | 2 |
| 80309 | 64 | C | 12 | 2 |
| 80310 | 64 | C | 12 | 2 |
| 80314 | 64 | C | 12 | 2 |
| 80321 | 64 | C | 12 | 2 |
| 80308 | 68 | C | 12 | 2 |
| 80306 | 68 | C | 12 | 2 |
| 80329 | 64 | C | 12 | 2 |
| 80328 | 64 | C | 12 | 2 |
| 80323 | 64 | C | 12 | 2 |
Common Questions About Boulder Water
These are the most common questions residents search for about water quality in Boulder, Colorado:
Is Boulder water hard or soft? Water hardness varies by source. Boulder's 5 water systems use multiple sources. Check your ZIP code report for specific hardness data.
Can I drink Boulder tap water? Boulder's water receives a grade of C (62/100). There are 32 health-based violations — consider filtration.
What is the best water filter for Boulder? A NSF/ANSI 53-certified filter for lead removal is a good general choice. See our Water Filter Matcher for personalized recommendations.
Boulder vs. Colorado Average
Understanding how Boulder compares to the broader Colorado average helps contextualize your local water quality. Factors like water source, treatment methods, and infrastructure age all contribute to differences between cities in the same state.
To see how individual neighborhoods compare, check the ZIP code reports below — water quality can vary significantly even within Boulder.
ZIP Codes in Boulder
Boulder spans 16 ZIP codes. The ZIP with the lowest water quality score is 80301. Each ZIP code has its own water quality profile based on the specific water system serving that area. Check each ZIP code for detailed contaminant data, violation history, and system information.
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Lead/copper: EPA Lead and Copper Rule sampling data
- Radon: EPA Map of Radon Zones
- Enforcement: EPA ECHO database
- Filter recommendations: NSF/ANSI certified products
Updated daily.