Tap Water Results

Is Islip, NY tap water safe?

Data: U.S. EPA · How we read the data · How we check it

Summary

Suffolk County Water Authority, the largest system here, had PFAS above the 2024 federal limits (PFOA, PFOS) in EPA's 2023–2025 testing.

Is it an emergency? No: PFAS limits are about years of exposure, not a glass of water, and nothing in EPA's data calls for you to stop drinking the water today. If your utility issues a boil-water or do-not-drink notice, follow it.

3 public water systems serve parts of Islip. The largest, Suffolk County Water Authority, serves 1.1 million people, and one system here had PFAS above a federal limit. Your water bill names your system.

Largest system

Suffolk County Water Authority

1.1 million people · Groundwater · EPA ID NY5110526

PFASHighest averageLimitStatus
PFOA
Above limit
6.05 ppt4 pptAbove limit
PFOS
Above limit
12.1 ppt4 pptAbove limit
PFHxS
Detected, below limit
6.85 ppt10 pptDetected, below limit
PFNA
Detected, below limit
4.95 ppt10 pptDetected, below limit
HFPO-DA (GenX)
Not detected
–10 pptNot detected

ppt = parts per trillion. "Highest average" is the highest average at any of the system's entry points, the way EPA compares results with the limits.

For context: the PFOA average is higher than at 95% of the New York systems EPA tested and the PFOS average is higher than at 99% of the New York systems EPA tested.

Lead: 1.25 ppb at the 90th percentile (Nov 2026, and 9 in 10 homes sampled were at or below it) Below action level
Health-based violations since 2016: 1

Full Suffolk County Water Authority results

Across New York, 31 of 322 water systems EPA tested had PFAS above a 2024 federal limit, and 16 systems were above the lead action level in results from the last five years. New York results.

Islip homes and lead pipes

75%
of homes built before 1980 (New York 74%, US 50%)
14%
built before 1950 (New York 38%)
20%
of households rent (New York 46%)

Lead service lines and lead solder were allowed until 1986, so homes from before then are the ones to check. Suffolk County Water Authority publishes a service line inventory you can search by address. Look up your address. How to check your own line.

Housing: Census American Community Survey 2020–2024 5-year estimates for Islip town (tables B25034, B25003). Estimates for small places have a margin of error.

Other water systems serving Islip

  • Ocean Beach Water District
    4,500 people · Groundwater · New York · lists this city
    No PFAS above limits
  • Saltaire Water District
    2,000 people · Groundwater · New York · lists this city
    Not in EPA's PFAS sample

How nearby cities compare

CityMain water systemPFASLead (90th pct.)
Babylon 8 mi
Suffolk County Water Authority
Suffolk County Water AuthorityAbove limit1.25 ppb
Smithtown 14 mi
Suffolk County Water Authority
Suffolk County Water AuthorityAbove limit1.25 ppb
Huntington 15 mi
Suffolk County Water Authority
Suffolk County Water AuthorityAbove limit1.25 ppb
Brookhaven 16 mi
Suffolk County Water Authority
Suffolk County Water AuthorityAbove limit1.25 ppb
Oyster Bay 18 mi
Jericho Water District
Jericho Water DistrictNone above limits2 ppb
Freeport 21 mi
Village of Freeport
Village of FreeportNone above limits3 ppb
Islip ZIP codes (19)
  • 11705
  • 11706
  • 11716
  • 11717
  • 11718
  • 11722
  • 11730
  • 11739
  • 11741
  • 11749
  • 11751
  • 11752
  • 11769
  • 11770
  • 11779
  • 11782
  • 11788
  • 11795
  • 11796

Questions

Is Islip tap water safe to drink?

Suffolk County Water Authority had 1 health-based violation since 2016, and EPA testing found PFAS above the 2024 federal limits, which it must meet by 2029. Utility data can't show lead from your own pipes: if your home was built before 1986, test your tap. Your utility's annual Consumer Confidence Report is the official summary.

Who supplies water in Islip, NY?

3 public water systems serve parts of Islip. The largest is Suffolk County Water Authority (1.1 million people). Your water bill names your system. The EPA ID is also on your utility's Consumer Confidence Report.

Does Islip tap water have PFAS?

Yes. EPA's 2023–2025 testing found entry-point averages above the 2024 federal limits for PFOA and PFOS at Suffolk County Water Authority. Systems have until 2029 to meet them.

Do Islip homes have lead pipes?

Census estimates put 75% of Islip homes as built before 1980 (New York: 74%). Lead service lines and lead solder were allowed until 1986, so older homes are more likely to have them. Suffolk County Water Authority's service line inventory says what your line is made of. The only way to know for your home is to check the line where it enters the house and test your tap.

Source: U.S. EPA drinking water records and PFAS testing (UCMR 5). How we read the data.