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Tap water quality report

Southold, NY

EPA monitoring detected 11 contaminants across the 3 water suppliers serving Southold. A detection doesn't automatically mean the water is unsafe — see the level at the main supplier for each below, with its EPA source and period.

3
water suppliers
1,102,430
people served
11
contaminants found
New York rankings Lead in New York PFAS in New York

What was found in Southold's water

The level at the city's main supplier, the highest level anywhere in the city, the EPA limit for each, and where every figure comes from.

ContaminantLevel vs EPA limitSuppliersSource
Pfhxa
0.0435 µg/L
No EPA limit set
Main supplier: SUFFOLK COUNTY WATER AUTHORITY · 1,100,000 people · 2025
1/3 UCMR-5
Pfpea
0.0394 µg/L
No EPA limit set
Main supplier: SUFFOLK COUNTY WATER AUTHORITY · 1,100,000 people · 2025
1/3 UCMR-5
6:2 Fts
0.0236 µg/L
No EPA limit set
Main supplier: SUFFOLK COUNTY WATER AUTHORITY · 1,100,000 people · 2025
1/3 UCMR-5
PFOS
0.0174 µg/L
No EPA limit set
Main supplier: SUFFOLK COUNTY WATER AUTHORITY · 1,100,000 people · 2025
1/3 UCMR-5
Pfba
0.0126 µg/L
No EPA limit set
Main supplier: SUFFOLK COUNTY WATER AUTHORITY · 1,100,000 people · 2025
1/3 UCMR-5
PFHXS
0.0108 µg/L
No EPA limit set
Main supplier: SUFFOLK COUNTY WATER AUTHORITY · 1,100,000 people · 2025
1/3 UCMR-5
Pfhpa
0.0096 µg/L
No EPA limit set
Main supplier: SUFFOLK COUNTY WATER AUTHORITY · 1,100,000 people · 2025
1/3 UCMR-5
PFOA
0.0065 µg/L
No EPA limit set
Main supplier: SUFFOLK COUNTY WATER AUTHORITY · 1,100,000 people · 2025
1/3 UCMR-5
PFNA
0.0057 µg/L
No EPA limit set
Main supplier: SUFFOLK COUNTY WATER AUTHORITY · 1,100,000 people · 2025
1/3 UCMR-5
PFBS
0.0052 µg/L
No EPA limit set
Main supplier: SUFFOLK COUNTY WATER AUTHORITY · 1,100,000 people · 2025
1/3 UCMR-5
Lead
0.0013 mg/L 8.3%
of the EPA limit 0.0150 mg/L
Main supplier: SUFFOLK COUNTY WATER AUTHORITY · 1,100,000 people · 2027
3/3 LCR
Each bar shows the measured level as a share of the EPA limit: green is well under, amber is close to it, red is over. For lead and copper the limit applies to exactly the 90th-percentile figure shown, so red there means a real exceedance. For everything else the limit applies to a running annual average while the figure is the 95th percentile of the system's samples — over 100% is worth reading, but is not by itself a violation. Formal violations are listed separately. These are the utilities' own EPA-reported results, not a city-wide average. A detection means the lab measured the substance — it isn't the same as exceeding a legal limit. Hover a source tag to see the EPA program and years behind each figure.

Water suppliers serving Southold

SupplierPopulation served
SUFFOLK COUNTY WATER AUTHORITY 1,100,000
GREENPORT WATER DISTRICT 2,050
FISHERS ISLAND WATER WORKS 380

Frequently asked questions about Southold tap water

Is Southold tap water safe to drink?

EPA testing detected 11 contaminants in the water serving Southold. A detection isn't the same as a violation — most detected levels are within federal limits. Check the level and source for each contaminant above, and your utility's annual Consumer Confidence Report for the official compliance status.

How many water suppliers serve Southold?

3 public water suppliers report drinking-water monitoring for Southold, New York to the EPA. Each is listed above with its population served.

What contaminants are in Southold's water?

The contaminants EPA monitoring detected in Southold include Pfhxa, Pfpea, 6:2 Fts, PFOS, Pfba. The full list, with the level at the main supplier and the data source, is in the table above.

Where does this data come from?

Every figure is official EPA drinking-water monitoring — the Lead & Copper Rule, the UCMR-5 nationwide testing program, and the EPA Six-Year Review — not our own testing. Each number is labelled with its source and period.