Open dataset
U.S. drinking water — every contaminant, every federal limit, in one dataset.
Every number on this site is transcribed from a utility's own annual drinking-water report and compared to the federal limit. Free to read, free to query, free to redistribute. CC BY 4.0.
Most-measured contaminants
Browse every contaminant, A–Z → — each defined, with every system that reports it.
See the PFAS Hotspots leaderboard → — every U.S. system over EPA's finalized PFAS limit, from the UCMR5 lab dataset.
Get the data
How the data is built
Every U.S. public water utility is required to publish an annual Consumer Confidence Report. We collect those PDFs, transcribe each contaminant measurement into a structured row, and surface it on a per-city page alongside the federal limit. The source document is archived and linked from every page so any figure can be checked.
Contaminant rollup logic, the "over the limit" threshold, and the federal-standard preference rules are documented in the code and on the API page.