Suffolk County Water Quality: 3 Cities Ranked by the Records
Suffolk County, New York: 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.
Perfluorooctanesulfonic acid (PFOS)Detected in 1 system of 3 tested4.0 ng/L federal MCL (2024) · US EPAHighest5.2 ng/L
- RIVERHEAD WATER DISTRICT5.2 ng/LSample date: 2023-06-14 to 2024-01-17
- GREENLAWN WATER DISTRICTNot detected · below 4.0 ng/L lab reporting limitSample date: 2023-10-23 to 2024-08-14
- HAMPTON BAYS WATER DISTRICTNot detected · below 4.0 ng/L lab reporting limitSample date: 2023-04-12 to 2024-07-30
Perfluorooctanoic acid (PFOA)Detected in 1 system of 3 tested4.0 ng/L federal MCL (2024) · US EPAHighest4 ng/L
- RIVERHEAD WATER DISTRICT4 ng/LSample date: 2023-06-14 to 2024-01-17
- GREENLAWN WATER DISTRICTNot detected · below 4.0 ng/L lab reporting limitSample date: 2023-10-23 to 2024-08-14
- HAMPTON BAYS WATER DISTRICTNot detected · below 4.0 ng/L lab reporting limitSample date: 2023-04-12 to 2024-07-30
Perfluorohexanesulfonic acid (PFHxS)Detected in 1 system of 3 tested10 ng/L federal MCL (2024) · US EPAHighest3.2 ng/L
- GREENLAWN WATER DISTRICT3.2 ng/LSample date: 2023-10-23 to 2024-08-14
- HAMPTON BAYS WATER DISTRICTNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-04-12 to 2024-07-30
- RIVERHEAD WATER DISTRICTNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-06-14 to 2024-01-17
Lead (90th percentile)Detected in 3 systems15 µg/L federal action level · US EPAHighest2 µg/L
- RIVERHEAD WATER DISTRICT2 µg/LMonitoring period: 2025–2027 (still open)
- HAMPTON BAYS WATER DISTRICT1.3 µg/LMonitoring period: 2025–2027 (still open)
- GREENLAWN WATER DISTRICT1 µg/LMonitoring period: 2025–2027 (still open)
Perfluorohexanoic acid (PFHxA)Detected in 1 system of 3 tested400,000 ng/L Michigan EGLE state MCL (strictest US state) · Michigan EGLEHighest3.3 ng/L
- RIVERHEAD WATER DISTRICT3.3 ng/LSample date: 2023-06-14 to 2024-01-17
- GREENLAWN WATER DISTRICTNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-10-23 to 2024-08-14
- HAMPTON BAYS WATER DISTRICTNot detected · below 3.0 ng/L lab reporting limitSample date: 2023-04-12 to 2024-07-30
1H, 1H, 2H, 2H-perfluorooctane sulfonic acid (6:2 FTS)Detected in 1 system of 3 testedNo federal or state limit; shown for transparencyHighest11 ng/L
- GREENLAWN WATER DISTRICT11 ng/LSample date: 2023-10-23 to 2024-08-14
- HAMPTON BAYS WATER DISTRICTNot detected · below 5.0 ng/L lab reporting limitSample date: 2023-04-12 to 2024-07-30
- RIVERHEAD WATER DISTRICTNot detected · below 5.0 ng/L lab reporting limitSample date: 2023-06-14 to 2024-01-17
Perfluoropentanoic acid (PFPeA)Detected in 3 systemsNo federal or state limit; shown for transparencyHighest5.4 ng/L
- HAMPTON BAYS WATER DISTRICT5.4 ng/LSample date: 2023-04-12 to 2024-07-30
- GREENLAWN WATER DISTRICT3.3 ng/LSample date: 2023-10-23 to 2024-08-14
- RIVERHEAD WATER DISTRICT3.2 ng/LSample date: 2023-06-14 to 2024-01-17
24 substances tested, none detected in any systemShow
Tested in these 3 systems: GREENLAWN WATER DISTRICT, HAMPTON BAYS WATER DISTRICT, RIVERHEAD WATER DISTRICT
- 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)
- 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)
- Perfluorobutanesulfonic acid (PFBS)
- Perfluorobutanoic acid (PFBA)
- 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 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 New YorkLargest water systems
- GreenlawnGREENLAWN WATER DISTRICT · NY510327142,000 served
- RiverheadRIVERHEAD WATER DISTRICT · NY510370535,000 served
- Hampton BaysHAMPTON BAYS WATER DISTRICT · NY510370412,500 served
Frequently asked
How does Suffolk County tap water compare across cities?
PurityMap ranks 3 cities in Suffolk 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 Hampton Bays's main water system: HAMPTON BAYS WATER DISTRICT · PWSID NY5103704 · Purity Score 99 (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 Suffolk County cities have PFAS above the federal limit?
1 city of 3 had at least one regulated PFAS (PFOA, PFOS or PFHxS) measured above the 2024 federal limit in EPA's UCMR 5 testing, including Riverhead (PFOS 5.2 ng/L). PFAS were detected at any level in 3.
Is there lead in Suffolk County tap water?
Utilities report lead as a 90th-percentile result from home taps. 3 of 3 Suffolk 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.
Have Suffolk County water systems had drinking-water violations?
1 city in Suffolk County has a health-based violation in the federal SDWIS record within about the last ten years. Each city report lists the contaminant, year and whether it was resolved.
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