New Haven County Water Quality: 4 Cities Ranked by the Records
New Haven County, Connecticut: 4 city reports built from EPA and utility records. A county has many suppliers; each city shows the system that serves it.
Highest result for each contaminant
One row per contaminant: the highest result any system in the county reported, against its limit. Open a row for the systems behind it.
Perfluorooctanesulfonic acid (PFOS)Detected in 2 systems of 4 tested4.0 ng/L federal MCL (2024) · US EPAHighest10.7 ng/L
- REGIONAL WATER AUTHORITY10.7 ng/LSample date: 2023-09-18 to 2024-06-11
- MERIDEN WATER DIVISION9.5 ng/LSample date: 2023-07-26 to 2024-04-30
- CTWC - NAUGATUCK REGION-CENTRAL SYSTEMNot detected · below 4.0 ng/L lab reporting limitSample date: 2023-04-11 to 2024-01-16
- WATERBURY WATER DEPARTMENTNot detected · below 4.0 ng/L lab reporting limitSample date: 2023-10-06 to 2024-06-04
Perfluorooctanoic acid (PFOA)Detected in 2 systems of 4 tested4.0 ng/L federal MCL (2024) · US EPAHighest7.1 ng/L
- REGIONAL WATER AUTHORITY7.1 ng/LSample date: 2023-09-18 to 2024-06-11
- MERIDEN WATER DIVISION6.1 ng/LSample date: 2023-07-26 to 2024-04-30
- CTWC - NAUGATUCK REGION-CENTRAL SYSTEMNot detected · below 4.0 ng/L lab reporting limitSample date: 2023-04-11 to 2024-01-16
- WATERBURY WATER DEPARTMENTNot detected · below 4.0 ng/L lab reporting limitSample date: 2023-10-06 to 2024-06-04
Perfluorohexanesulfonic acid (PFHxS)Detected in 1 system of 4 tested10 ng/L federal MCL (2024) · US EPAHighest4 ng/L
- MERIDEN WATER DIVISION4 ng/LSample date: 2023-07-26 to 2024-04-30
- CTWC - NAUGATUCK REGION-CENTRAL SYSTEMNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-04-11 to 2024-01-16
- REGIONAL WATER AUTHORITYNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-09-18 to 2024-06-11
- WATERBURY WATER DEPARTMENTNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-10-06 to 2024-06-04
Lead (90th percentile)Detected in 1 system of 4 tested15 µg/L federal action level · US EPAHighest4 µg/L
- WATERBURY WATER DEPARTMENT4 µg/LMonitoring period: 2023–2025
- CTWC - NAUGATUCK REGION-CENTRAL SYSTEMNot detectedMonitoring period: 2026–2026 (still open)
- MERIDEN WATER DIVISIONNot detectedMonitoring period: 2026–2026 (still open)
- REGIONAL WATER AUTHORITYNot detectedMonitoring period: 2024–2026 (still open)
Perfluorobutanesulfonic acid (PFBS)Detected in 2 systems of 4 tested2,000 ng/L EPA health advisory (screening, not a legal limit) · US EPAHighest3.7 ng/L
- MERIDEN WATER DIVISION3.7 ng/LSample date: 2023-07-26 to 2024-04-30
- REGIONAL WATER AUTHORITY3.5 ng/LSample date: 2023-09-18 to 2024-06-11
- CTWC - NAUGATUCK REGION-CENTRAL SYSTEMNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-04-11 to 2024-01-16
- WATERBURY WATER DEPARTMENTNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-10-06 to 2024-06-04
Perfluorohexanoic acid (PFHxA)Detected in 1 system of 4 tested400,000 ng/L Michigan EGLE state MCL (strictest US state) · Michigan EGLEHighest5.8 ng/L
- MERIDEN WATER DIVISION5.8 ng/LSample date: 2023-07-26 to 2024-04-30
- CTWC - NAUGATUCK REGION-CENTRAL SYSTEMNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-04-11 to 2024-01-16
- REGIONAL WATER AUTHORITYNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-09-18 to 2024-06-11
- WATERBURY WATER DEPARTMENTNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-10-06 to 2024-06-04
Perfluorobutanoic acid (PFBA)Detected in 1 system of 4 testedNo federal or state limit; shown for transparencyHighest5 ng/L
- MERIDEN WATER DIVISION5 ng/LSample date: 2023-07-26 to 2024-04-30
- CTWC - NAUGATUCK REGION-CENTRAL SYSTEMNot detected · below 5.0 ng/L lab reporting limitSample date: 2023-04-11 to 2024-01-16
- REGIONAL WATER AUTHORITYNot detected · below 5.0 ng/L lab reporting limitSample date: 2023-09-18 to 2024-06-11
- WATERBURY WATER DEPARTMENTNot detected · below 5.0 ng/L lab reporting limitSample date: 2023-10-06 to 2024-06-04
Perfluoropentanoic acid (PFPeA)Detected in 2 systems of 4 testedNo federal or state limit; shown for transparencyHighest4.8 ng/L
- MERIDEN WATER DIVISION4.8 ng/LSample date: 2023-07-26 to 2024-04-30
- REGIONAL WATER AUTHORITY3.1 ng/LSample date: 2023-09-18 to 2024-06-11
- CTWC - NAUGATUCK REGION-CENTRAL SYSTEMNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-04-11 to 2024-01-16
- WATERBURY WATER DEPARTMENTNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-10-06 to 2024-06-04
23 substances tested, none detected in any systemShow
Tested in these 4 systems: CTWC - NAUGATUCK REGION-CENTRAL SYSTEM, MERIDEN WATER DIVISION, REGIONAL WATER AUTHORITY, WATERBURY WATER DEPARTMENT
- 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS)
- 1H, 1H, 2H, 2H-perfluorodecane sulfonic acid (8:2 FTS)
- 1H, 1H, 2H, 2H-perfluorohexane sulfonic acid (4:2 FTS)
- 1H, 1H, 2H, 2H-perfluorooctane sulfonic acid (6:2 FTS)
- 4,8-Dioxa-3H-perfluorononanoic acid (ADONA)
- 9-Chlorohexadecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS)
- Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals)
- Lithium
- N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA)
- N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA)
- Nonafluoro-3,6-dioxaheptanoic acid (NFDHA)
- Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA)
- Perfluoro-3-methoxypropanoic acid (PFMPA)
- Perfluoro-4-methoxybutanoic acid (PFMBA)
- Perfluorodecanoic acid (PFDA)
- Perfluorododecanoic acid (PFDoA)
- Perfluoroheptanesulfonic acid (PFHpS)
- Perfluoroheptanoic acid (PFHpA)
- Perfluorononanoic acid (PFNA)
- Perfluoropentanesulfonic acid (PFPeS)
- Perfluorotetradecanoic acid (PFTA)
- Perfluorotridecanoic acid (PFTrDA)
- Perfluoroundecanoic acid (PFUnA)
Cities ranked by the records
Ranked by the Purity Score of each city's main water system, highest first. Scores belong to water systems; there is no county score. The score is computed only from contaminants measured in the published EPA record, so this ranks the record, not which city's water is safest. How the score works.
0of 4 cities above the 15 µg/L action level
Based on each system's 90th-percentile result. Lead from household plumbing isn't in this record.
Lead in ConnecticutLargest water systems
Frequently asked
How does New Haven County tap water compare across cities?
PurityMap ranks 4 cities in New Haven County by the Purity Score of each city's main water system, computed only from contaminants measured in the published EPA record. Scores belong to water systems, not to cities. The highest published score is Naugatuck's main water system: CTWC - NAUGATUCK REGION-CENTRAL SYSTEM · PWSID CT0880011 · Purity Score 100 (Excellent) · Confidence: moderate · Assessed at the water-system level. The ranking compares the records, not which city's water is safest, and your own tap can differ with household plumbing.
How many New Haven County cities had a PFAS sample above a 2024 EPA limit?
2 of 4 New Haven County city reports had a PFAS sample above a 2024 EPA limit in EPA's UCMR 5 testing, including New Haven (PFOS 10.7 ng/L), Meriden (PFOS 9.5 ng/L). That limit is judged on a yearly average, and water systems have until 2029 to meet it, so a single sample is not a violation. PFAS were detected at any level in 2.
Is there lead in New Haven County tap water?
Utilities report lead as a 90th-percentile result from home taps. 1 of 4 New Haven County cities reported a value above zero, and none was above the 15 µg/L federal action level. Lead usually comes from a building's own pipes and fixtures, so only a test at your tap tells you what you drink.
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