How many water violations are in Suffolk County?

Suffolk County has 3,402 total drinking water violations across 152 water systems, of which 513 are health-based violations. 80.9% of systems have at least one violation.

How many people get water from Suffolk County systems?

Water systems in Suffolk County serve approximately 1,387,905 people through 152 public water systems.

Has PFAS been detected in Suffolk County water?

Under EPA UCMR5, 7 of 10 tested systems in Suffolk County had at least one PFAS detection (70.0% of the UCMR5-tested subset - not of all 152 SDWIS systems).

What types of water sources supply Suffolk County?

Water systems in Suffolk County use GW (151 systems), SW (1 systems) as their primary water sources.

Are health-based violations serious?

Health-based violations indicate that drinking water exceeded Maximum Contaminant Levels (MCLs) set by the EPA or failed treatment technique requirements. 15.1% of Suffolk County's violations are health-based. Among counties with any SDWIS violations, this extract puts Suffolk County in the middle health-based share band. Not all violations indicate immediate health risk, but they require corrective action.

Where does Suffolk County sit among U.S. counties for water-system population?

According to EPA SDWIS county population served used on /counties, Suffolk County ranks #35 of 3,254 counties by people served, and #2 of 58 counties in New York. Ordinals use the same total_population DESC sort as the counties directory. See /methodology#corpus-placement.

Counties → New York

Suffolk County, New York

Compiled by PlainWater · May 15, 2026

SDWIS compliance plate

Sheet NY103 · Suffolk County 152 sys · 3,402 viol · #35/3254

VIOL-SEVERE · HEALTH-LOW · RANK-TOP · ABOVE-PEER · PFAS-HIGH · SRC-GW · SYS-LARGE · BOOK-FULL

VIOL-SEVERE 80.9% flagged
HEALTH-LOW 15.1% health
RANK-TOP #35/3254
ABOVE-PEER +1.3 pp
PFAS-HIGH 70.0% detect
SRC-GW GW lead 99%
SYS-LARGE 152 systems
BOOK-FULL 7/7 fields

Nearest flagged-rate peer: Rockland County ( -1.3 pp flagged-rate)

According to EPA SDWIS county population served used on /counties, Suffolk County ranks #35 of 3,254 counties by people served, and #2 of 58 counties in New York. See methodology · corpus placement.

Suffolk County standing, lower-flagged corpus third

Flagged-system rate 80.9% is at or below the corpus lower third (≤ 92.7% flagged) across 2,973 counties with ≥3 SDWIS systems . Health-based share 15.1% is health-based share in the middle third (≤ 24.5%) . UCMR5 detect rate 70.0% is UCMR5 detect rate above the tested-pool upper third (> 33.3%) . Population served ranks #35 of 3,254 · #2 of 58 in New York.

Water Systems

System Name	Population	Violations	PFAS
Suffolk County Water Authority	1,100,000	42	Detected
South Huntington Water District	81,760	11	Clean
Greenlawn Water District	42,000	87	Detected
Riverhead Water District	35,000	156	Detected
Dix Hills Water District	34,522	89	Detected
Smithtown Water District	19,635	10	Clean
Hampton Bays Water District	12,500	106	Detected
Robert Moses State Park	11,600	126	-
St James Water District	10,587	9	Detected
Ocean Beach Water District	4,500	226	Clean
Captree State Park	4,100	9	-
Brookhaven National Laboratory	3,500	3	Detected
Northport VA Hospital	3,088	221	-
Greenport Water District	2,050	29	-
Riverside Water District	2,050	3	-
Saltaire Water District	2,000	88	-
Seaview Water Company	1,400	42	-
Valero	1,000	3	-
Calverton Hills Owners Association	897	220	-
Orient Beach State Park	800	8	-
Gilgo Beach	500	3	-
Cedar Beach (Golf Course/Concession)	500	10	-
Kingdom Hall of Jehovah Witnesses	500	0	-
East Moriches Primary Care	500	0	-
Shelter Island Heights Association	463	330	-
Overlook Beach	450	0	-
Shelter Island School	315	13	-
Fishers Island Water Works	300	183	-
West Gilgo Beach Association	300	14	-
Shelter Island Library	258	2	-
Dering Harbor Corp	250	9	-
Camp Blue Bay	200	15	-
Cedar Beach Sportfishing Educ. Center	200	3	-
Atlantic Bluffs Club	200	0	-
Long Island Game Farm	200	18	-
Caribbean Spot	200	6	-
Swans Marina	200	13	-
Joes Kwik Mart	200	6	-
Sag Harbor State Golf Course	200	6	-
Speedway #7794 (Fna Hess General Store)	200	0	-
1983 Montauk Hwy Offices Coparts	190	16	-
Coecles Harbor Marina	150	6	-
Camp Quinipet	150	45	-
D. S. Shanahans	150	4	-
Townline BBQ	150	0	-
Old Stove Pub	150	39	-
Hampton Hills Golf Club	150	4	-
Rock Hill Country Club	150	6	-
La Antigua	150	3	-
Whales Tale	150	3	-

Compare beyond New York

Lower-flagged peers for Suffolk County

Cross-state counties nearest Suffolk County on flagged-system share (80.9%) and cumulative violation count (3,402). In-state neighbours stay on the compliance plate above.

Similar flagged-system rate

Nearest cross-state counties by % of SDWIS systems with at least one violation on record.

4 peers

Similar violation load

Nearest cross-state counties by cumulative SDWIS violation count (all systems in the county).

4 peers

Read our methodology · Check your water system - how this data is sourced, computed, and verified.

Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater

Compiled by PlainWater, Drinking Water Quality Editorial Process · May 15, 2026

Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This page draws directly on EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.