Provenance record · public source
Fifth Unregulated Contaminant Monitoring Rule (UCMR5) — PFAS occurrence data
Nationwide entry-point monitoring for 29 PFAS and lithium under the fifth UCMR cycle.
What this source covers
- Coverage
- U.S. public water systems in the fifth UCMR monitoring cycle · sampling year 2024
- Used by PurityMap
- Results for 29 PFAS and lithium at each system’s entry points
- Document type
- UCMR5 Analytical Results
What it can’t tell you
- Results are entry-point-to-distribution samples, not household-tap measurements.
- It covers the public water systems in the UCMR 5 sample: those serving 3,300 people or more and a representative set of smaller ones. Private wells have no record here.
- Publication lag: EPA releases results in batches, so the newest samples may not be in this file yet.
How PurityMap uses it
From the file to 17,203 findings
- Step 1
Ingest the national file
UCMR5_All.txt from EPA’s UCMR 5 occurrence data, collected 2026-01-15.
- Step 2
Keep each system’s results
Every sample per analyte, with sample dates and the minimum reporting level.
- Step 3
Compare with a cited reference
The highest detected value per analyte, compared with its cited limit or reference where one exists.
- Step 4
17,203 findings depend on it
Each finding links back here, so you can trace a value to this record.
Update history
When this source last changed
UCMR5 PFAS occurrence data ingested and linked to system findings.
How to interpret this source
A source is a public record, not a verdict.
Coverage, sampling location, reporting limits, and publication lag determine what any finding drawn from it can support.