Fairfield County Water Quality: 3 Cities Ranked by the Records
Fairfield County, Connecticut: 3 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.
Perfluorooctanoic acid (PFOA)Detected in 3 systems4.0 ng/L federal MCL (2024) · US EPAHighest10.9 ng/L
- AQUARION-EASTERN FAIRFIELD COUNTY10.9 ng/LSample date: 2023-01-17 to 2024-02-20
- BETHEL WATER DEPT5.9 ng/LSample date: 2024-03-05 to 2024-09-10
- DANBURY WATER DEPARTMENT5.4 ng/LSample date: 2024-12-10 to 2025-09-17
Perfluorooctanesulfonic acid (PFOS)Detected in 1 system of 3 tested4.0 ng/L federal MCL (2024) · US EPAHighest6.6 ng/L
- AQUARION-EASTERN FAIRFIELD COUNTY6.6 ng/LSample date: 2023-01-17 to 2024-02-20
- BETHEL WATER DEPTNot detected · below 4.0 ng/L lab reporting limitSample date: 2024-03-05 to 2024-09-10
- DANBURY WATER DEPARTMENTNot detected · below 4.0 ng/L lab reporting limitSample date: 2024-12-10 to 2025-09-17
Perfluorobutanesulfonic acid (PFBS)Detected in 3 systems2,000 ng/L EPA health advisory (screening, not a legal limit) · US EPAHighest4.3 ng/L
- DANBURY WATER DEPARTMENT4.3 ng/LSample date: 2024-12-10 to 2025-09-17
- AQUARION-EASTERN FAIRFIELD COUNTY4.1 ng/LSample date: 2023-01-17 to 2024-02-20
- BETHEL WATER DEPT3.9 ng/LSample date: 2024-03-05 to 2024-09-10
Perfluorohexanoic acid (PFHxA)Detected in 2 systems of 3 tested400,000 ng/L Michigan EGLE state MCL (strictest US state) · Michigan EGLEHighest7.4 ng/L
- AQUARION-EASTERN FAIRFIELD COUNTY7.4 ng/LSample date: 2023-01-17 to 2024-02-20
- DANBURY WATER DEPARTMENT3.6 ng/LSample date: 2024-12-10 to 2025-09-17
- BETHEL WATER DEPTNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-03-05 to 2024-09-10
Perfluorobutanoic acid (PFBA)Detected in 1 system of 3 testedNo federal or state limit; shown for transparencyHighest7.6 ng/L
- AQUARION-EASTERN FAIRFIELD COUNTY7.6 ng/LSample date: 2023-01-17 to 2024-02-20
- BETHEL WATER DEPTNot detected · below 5.0 ng/L lab reporting limitSample date: 2024-03-05 to 2024-09-10
- DANBURY WATER DEPARTMENTNot detected · below 5.0 ng/L lab reporting limitSample date: 2024-12-10 to 2025-09-17
Perfluoroheptanoic acid (PFHpA)Detected in 1 system of 3 testedNo federal or state limit; shown for transparencyHighest3.9 ng/L
- AQUARION-EASTERN FAIRFIELD COUNTY3.9 ng/LSample date: 2023-01-17 to 2024-02-20
- BETHEL WATER DEPTNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-03-05 to 2024-09-10
- DANBURY WATER DEPARTMENTNot detected · below 3.0 ng/L lab reporting limitSample date: 2024-12-10 to 2025-09-17
Perfluoropentanoic acid (PFPeA)Detected in 3 systemsNo federal or state limit; shown for transparencyHighest6.7 ng/L
- AQUARION-EASTERN FAIRFIELD COUNTY6.7 ng/LSample date: 2023-01-17 to 2024-02-20
- DANBURY WATER DEPARTMENT3.4 ng/LSample date: 2024-12-10 to 2025-09-17
- BETHEL WATER DEPT3 ng/LSample date: 2024-03-05 to 2024-09-10
24 substances tested, none detected in any systemShow
Tested in these 3 systems: AQUARION-EASTERN FAIRFIELD COUNTY, BETHEL WATER DEPT, DANBURY 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)
- Lead (90th percentile)
- 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)
- Perfluorohexanesulfonic acid (PFHxS)
- 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 3 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 Fairfield County tap water compare across cities?
PurityMap ranks 3 cities in Fairfield 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 Danbury's main water system: DANBURY WATER DEPARTMENT · PWSID CT0340011 · Purity Score 70 (Fair) · 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 Fairfield County cities had a PFAS sample above a 2024 EPA limit?
3 of 3 Fairfield County city reports had a PFAS sample above a 2024 EPA limit in EPA's UCMR 5 testing, including Stamford (PFOA 10.9 ng/L), Bethel (PFOA 5.9 ng/L), Danbury (PFOA 5.4 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 3.
Is there lead in Fairfield County tap water?
Utilities report lead as a 90th-percentile result from home taps. 0 of 3 Fairfield 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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