Government Data Watchlist
PFAS in U.S. Drinking Water
Official EPA UCMR 5 monitoring records for public water systems nationwide. Search for your water system below, or browse by state.
Search by utility name, city, or PWSID — 6,189 systems with official records
Data disclosure: This watchlist uses only EPA UCMR 5 and official government datasets. Monitoring results are not compliance determinations. Missing records do not establish absence of PFAS. Do not use this data as a substitute for official utility communications or professional water testing. Full methodology
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UCMR 5 Scope
Analytes Monitored
The following PFAS analytes were monitored under EPA UCMR 5. EPA limits shown are from the PFAS National Primary Drinking Water Regulation (April 2024). Results in this watchlist are monitoring data — not compliance determinations.
Source: EPA UCMR 5 Occurrence Data
Understanding the Data
Frequently Asked Questions
What is PFAS?
PFAS (per- and polyfluoroalkyl substances) are a large group of synthetic chemicals used in many products since the 1940s. Some PFAS have been found in drinking water sources. This watchlist displays only official government monitoring records — it does not make health judgments.
What is EPA UCMR 5?
UCMR 5 is the fifth Unregulated Contaminant Monitoring Rule, which required large public water systems to monitor for 29 PFAS and lithium between 2023 and 2025. EPA published the resulting occurrence data publicly. This watchlist uses only that official UCMR 5 dataset.
Does an official PFAS detection mean my water is unsafe?
No. This watchlist does not make safety determinations. An official detection means EPA monitoring records show a reported result for that analyte at that system. Whether that result has regulatory significance depends on the official EPA rules in effect at the time. See the EPA PFAS National Primary Drinking Water Regulation for current enforceable limits.
What does 'official non-detect' mean?
An official non-detect means the monitoring result was reported as not detected above the minimum reporting limit (MRL) for that analyte. It does not mean zero concentration — only that the concentration, if present, was below the detection threshold used.
Does missing data mean no PFAS?
No. Not all public water systems were required to participate in UCMR 5. Absence of a record means no qualifying official record was located in the current dataset — it does not establish that PFAS are absent.
How often is this data updated?
This watchlist refreshes each time EPA publishes updated UCMR 5 occurrence data. Each record shows its source retrieval date. Check the Sources page for current dataset versions.