We read 13 results from Riverhead Water District’s 2025 water quality report. 1 result over a legal limit and 5 above a health goal or guideline.
Serves about 35,000 people · Water system ID NY5103705 · Read the district’s 2025 report (opens in a new tab)
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Results from the 2025 report
Each number is copied from the district’s report and links to the page it’s printed on. Where the report lists several plants, wells or purchased water, the highest is shown.
| Contaminant | Result | Health goal | Legal limit | What it means |
|---|---|---|---|---|
| Perchloratehighest measured · range ND to 11.2 · listed as a violation in the report · Wells · 2025 report, page 3 | 11.2 ppb | 1 ppb | 6 ppb | Over the legal limit1.9x the legal limit |
| Arsenichighest measured · range ND to 5.9 · listed as a violation in the report · Wells · 2025 report, page 3 | 5.9 ppb | 0.004 ppb | 10 ppb | Above the health goal1,475x the health goal |
| Gross alpha (radioactivity)highest measured · range ND to 0.72 · listed as a violation in the report · Wells · 2025 report, page 4 | 0.72 pCi/L | 0 pCi/L | 15 pCi/L | Above the health goalThe health goal is zero |
| Gross beta (radioactivity)highest measured · range 0.38 to 1.41 · listed as a violation in the report · Wells · 2025 report, page 4 | 1.41 pCi/L | 0 pCi/L | 50 pCi/L | Above the health goalThe health goal is zero |
| Lead90th percentile of 32 homes tested · listed as a violation in the report · Customer taps · 2025 report, page 3 | 2 ppb | 0.2 ppb | 15 ppb (action level) | Above the health goal10x the health goal |
| Manganesehighest measured · range ND to 0.28 · listed as a violation in the report · Wells · 2025 report, page 3 | 0.28 ppm | — | 0.05 ppm guideline | Above the guideline5.6x the guideline (taste, odor or stains; not a health limit) |
| Bariumhighest measured · range ND to 0.07 · listed as a violation in the report · Wells · 2025 report, page 3 | 0.07 ppm | 2 ppm | 2 ppm | Below the health goal |
| Chloridehighest measured · range 5.3 to 40.8 · listed as a violation in the report · Wells · 2025 report, page 3 | 40.8 ppm | — | 250 ppm guideline | Within the guideline |
| Disinfection byproducts (TTHM)highest measured · range ND to 6.6 · listed as a violation in the report · Distribution system · 2025 report, page 3 | 6.6 ppb | None set | 80 ppb | Below the legal limit |
| Nitrate (as N)highest measured · range ND to 5.8 · listed as a violation in the report · Wells · 2025 report, page 3 | 5.8 ppm | 10 ppm | 10 ppm | Below the health goal |
| Sulfatehighest measured · range ND to 79.8 · listed as a violation in the report · Wells · 2025 report, page 3 | 79.8 ppm | — | 250 ppm guideline | Within the guideline |
| PFBA (a PFAS)highest measured · range ND to 2.51 · listed as a violation in the report · Wells · 2025 report, page 4 | 2.51 ppt | None set | None | No health limit |
| Sodiumhighest measured · range 4.6 to 21.8 · listed as a violation in the report · Wells · 2025 report, page 3 | 21.8 ppm | None set | None | No health limit |
Utility results describe the whole system, measured where water enters the pipes, not your tap. Your home’s plumbing can add lead or copper. 1 number we weren’t sure about is held back until a person checks.
EPA testing for PFAS and lithium
EPA’s own nationwide testing (UCMR 5) found these in Riverhead Water District’s water between Jun 2023 and Jan 2024. These are EPA lab results, separate from the district’s report. Anything not listed was not detected.
- PFOA4 pptFound in 1 of 20 samples · highest resultBelow the federal limit that takes effect in 2029 (4 ppt)
- PFOS5.2 pptFound in 1 of 20 samples · highest resultAbove the federal limit that takes effect in 2029 (4 ppt)
Source: EPA UCMR 5 occurrence data. The highest single result is shown; one high sample doesn’t mean every glass is that high.
What you can do
Nothing here is an emergency notice: if the district has a violation, it must tell customers directly. If you’d like to lower these at your tap, these are the treatments that remove them, and the catalog shows the models certified for each. Ranking is by certified removal; commissions never change the order.
Industrial chemicals and pesticides
Found: Perchlorate
What removes it: Carbon block or RO.
Radium and uranium
Found: Gross alpha (radioactivity), Gross beta (radioactivity)
What removes it: Reverse osmosis.
Lead
Found: Lead
What removes it: Certified carbon block or RO.
Sediment or cloudy water
Found: Manganese
What removes it: Oxidation filter.
PFAS ("forever chemicals")
Found: PFOS (EPA testing)
What removes it: Reverse osmosis.
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