How we check the data

Every number on this site comes from a public record, and every number is traced back to the exact line in the original report before it's published.

Where the data comes from

• Utility water quality reports (Consumer Confidence Reports). Every community water system must publish one each year. This is our main source for PFAS, lead and hardness.
• EPA's Safe Drinking Water Information System, for the list of water systems, who buys water from whom, and violations.
• EPA's fifth Unregulated Contaminant Monitoring Rule (UCMR 5), nationwide testing for 29 PFAS and lithium.
• U.S. Census Bureau geography and population estimates, to match ZIP codes and water systems to towns.

How each number is checked

We extract values from each report, then confirm that every value appears word for word in the original document. Any value we can't match to the report isn't published. Reports whose tables are images get a manual check instead.

We don't rely on EPA's records alone to say where a town's water comes from. In our checks, those records sometimes list a system as buying most of its water when the utility's own report says it runs its own wells. Where they disagree, we follow the utility's report.

Which limits we compare against

We show two limits side by side. New Jersey's limits are the ones utilities must meet today: 14 ppt for PFOA and 13 ppt for PFOS. EPA's national limits, set in 2024, are stricter: 4 ppt for each. A report that says a system is "in compliance" is usually measuring against New Jersey's limits.

EPA kept its 4 ppt limits for PFOA and PFOS. Utilities must meet them by 2029; EPA has proposed letting systems request until 2031. In May 2026, EPA proposed withdrawing its national limits for PFNA, PFHxS, GenX (HFPO-DA) and a combined limit for PFAS mixtures. The proposal isn't final yet; EPA plans to decide in 2026. New Jersey's own PFNA limit is unaffected. We'll update these pages when EPA decides. (Status as of September 2026.)

What we don't know

Utility reports describe water across a whole system. Your own tap can differ, especially for lead, which usually comes from pipes inside or leading to the home. Towns served by more than one water system are marked on their pages.

Corrections

If you see a number that doesn't match your utility's report, tell us. We check it against the source and correct the page.