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

ZipCheckup tracks EPA drinking-water compliance for 423 public water systems serving 235 ZIP codes in Connecticut. The state record shows 2,592 EPA violations, 106 health-based.

City Water Quality Map: Connecticut

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 Connecticut

#	City	Grade	Violations	Systems	Population
1	Brookfield		275	5	17,871	Details →
2	New Milford		167	5	27,133	Details →
3	Danbury		113	9	85,705	Details →
4	Trumbull		92	2	36,928	Details →
5	Bethel		78	4	20,498	Details →
6	New Fairfield		59	5	13,558	Details →
7	Storrs Mansfield		55	6	17,505	Details →
8	Southbury		52	3	19,973	Details →
9	Sandy Hook		52	3	11,808	Details →
10	Oakdale		46	5	7,547	Details →

Most Common Contaminants in Connecticut

Contaminant	Category	Violations	ZIPs Affected	Health Risk
Consumer Confidence Rule	Reporting	416	93	No
Lead and Copper Rule	Treatment Technique	217	92	Yes
Public Notice Rule	Reporting	110	45	No
Cadmium	Inorganic	91	46	No
Arsenic	Inorganic	90	45	No
Barium	Inorganic	90	45	No
Chromium	Inorganic	90	45	No
Cyanide	Inorganic	90	45	No
Mercury	Inorganic	90	45	No
Nickel	Inorganic	90	45	No

Water Quality Overview

Connecticut has 423 community water systems represented across 235 directly mapped ZIP records. The associated city records cover approximately 3,486,063 people. The available records contain 2,592 EPA violations, including 106 health-based violations.

Health-based violations account for 4% of all violations in Connecticut. 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	106	4.1%
Monitoring/Reporting	2,486	95.9%
Total	2,592	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 Connecticut 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 Connecticut:

Health-based violations have increased from 6 in 2021 to 14 in 2026. This trend warrants monitoring and may reflect expanded testing requirements rather than worsening quality.

Most Common Contaminants

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

How to Check Your Water in Connecticut

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 Connecticut. 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. Connecticut has 106 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 Connecticut?

Records for 423 community water systems mapped to ZIPs in Connecticut show 2,592 reported violations, including 106 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 Connecticut?

Connecticut has 2,592 EPA violations on record across 235 ZIP codes; 106 are classified as health-based violations. The remainder are monitoring or reporting violations.

Which city in Connecticut has the worst water quality?

Brookfield, CT has the most recorded EPA violations (275) among the cities with mapped water systems in Connecticut 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 Connecticut has the best water quality?

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

What contaminants are found in Connecticut drinking water?

EPA regulates over 90 drinking-water contaminants nationally; water systems in Connecticut 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.