Data: EPA Safe Drinking Water Information System (SDWIS), EPA ECHO

ZipCheckup tracks EPA drinking-water compliance for 561 public water systems serving 307 ZIP codes in Colorado. The state record shows 4,246 EPA violations, 498 health-based.

City Water Quality Map: Colorado

Each circle represents a city. Size indicates population, color indicates water quality grade. Tap a circle for details.

A B C D F Circle size = population

Cities with Most Violations in Colorado

#	City	Grade	Violations	Systems	Population
1	Colorado Springs		301	24	613,448	Details →
2	Telluride		172	2	5,626	Details →
3	Florissant		141	4	6,372	Details →
4	Ophir		134	1	144	Details →
5	Pueblo		123	5	161,607	Details →
6	Evergreen		113	5	24,877	Details →
7	Boulder		110	14	129,202	Details →
8	Alamosa		108	3	15,454	Details →
9	Leadville		106	2	7,049	Details →
10	Littleton		101	16	318,691	Details →

Most Common Contaminants in Colorado

Contaminant	Category	Violations	ZIPs Affected	Health Risk
Surface Water Treatment Rule	Treatment Technique	549	148	Yes
Public Notice Rule	Reporting	472	99	No
Interim Enhanced Surface Water Treatment Rule	Treatment Technique	463	163	Yes
Haloacetic Acids (HAA5)	Disinfection Byproducts	315	102	Yes
Total Trihalomethanes (TTHM)	Disinfection Byproducts	295	110	Yes
Lead and Copper Rule	Treatment Technique	295	113	Yes
Consumer Confidence Rule	Reporting	140	92	No
Chlorine	Disinfectant	117	77	No
Chlorite	Disinfection Byproducts	117	32	No
Combined Radium (-226 and -228)	Radionuclides	115	39	Yes

Water Quality Overview

Colorado has 561 community water systems represented across 307 directly mapped ZIP records. The associated city records cover approximately 5,599,404 people. The available records contain 4,246 EPA violations, including 498 health-based violations.

Health-based violations account for 12% of all violations in Colorado. These violations indicate contaminant levels that may pose direct risks to human health, as opposed to monitoring or reporting failures.

Violation Breakdown

Violation Type	Count	Percentage
Health-based	498	11.7%
Monitoring/Reporting	3,748	88.3%
Total	4,246	100%

Health-based violations are MCL, MRDL (disinfectant) and treatment-technique violations. Monitoring violations indicate failures to test or report - these do not necessarily mean unsafe water, but they mean the water was not properly verified.

Cities with Most Violations

The following cities in Colorado have the highest number of EPA violations:

Violation counts are cumulative across all water systems serving each city. Higher counts may reflect larger systems with more monitoring requirements, not necessarily worse water quality.

Violation Trend Over Time

Year-by-year EPA violations recorded across all water systems in Colorado:

Health-based violations have decreased from 100 in 2021 to 12 in 2026, suggesting improving compliance across Colorado.

Most Common Contaminants

The following contaminants have caused the most violations across Colorado water systems:

How to Check Your Water in Colorado

1. Enter your ZIP code on ZipCheckup for detailed water-system data including contaminant levels and violation history; the separate Home Safety Score is a multi-source index

2. Request your CCR - every water utility must provide an annual Consumer Confidence Report

3. Get a home test - certified kits ($20-$50) or professional lab tests ($150-$400)

4. Consider filtration - NSF-certified filters can address specific contaminants found in your area

EPA Enforcement

The EPA and state regulators have taken enforcement actions against water systems in Colorado. Enforcement actions range from compliance assistance to formal orders and penalties.

Data Sources

• Water quality: EPA Safe Drinking Water Information System (SDWIS)
• Enforcement: EPA ECHO

Updated daily.

What are EPA violations?

Health-based violations are EPA violations of a Maximum Contaminant Level (MCL), a Maximum Residual Disinfectant Level (MRDL) or a required treatment technique - the enforceable standards designed to protect human health. Colorado has 498 such violations across its water systems. Not all violations cause illness; review each violation type and duration to understand possible health implications.

Understanding water quality grades

ZipCheckup grades water systems from A to F based on EPA violation history, contaminant levels, and system compliance. Grades summarize ZipCheckup's scoring inputs; review the underlying records for specific issues. Grades are calculated per ZIP code and aggregated at the city, county, and state level.

Frequently Asked Questions

Is the tap water safe to drink in Colorado?

Records for 561 community water systems mapped to ZIPs in Colorado show 4,246 reported violations, including 498 health-based. Water quality varies by city and ZIP code - check your specific location for detailed results.

How many violations are on record for water systems serving Colorado?

Colorado has 4,246 EPA violations on record across 307 ZIP codes; 498 are classified as health-based violations. The remainder are monitoring or reporting violations.

Which city in Colorado has the worst water quality?

Colorado Springs, CO has the most recorded EPA violations (301) among the cities with mapped water systems in Colorado in our data. Check your water supplier's report and test your tap water for the most accurate picture of your local water quality.

Which city in Colorado has the best water quality?

Violation records vary by water system across Colorado. Check individual city reports for details.

What contaminants are found in Colorado drinking water?

EPA regulates over 90 drinking-water contaminants nationally; water systems in Colorado monitor those applicable to each system, which can include lead, copper, nitrate, disinfection byproducts, and bacteria. The most common violations vary by region - check your ZIP code for contaminant-specific data.