Research, explainers, and practical guides that connect public water evidence to the questions households actually ask.
28 published articles6 disciplines180 cited source recordsLatest 2026-11-04
EPA's 2024 sampling found a PFOS sample above the new 4.0 ng/L limit in 746 monitored cities. Here is what the records show and how to read them.
Federal monitoring recorded lead above the 15 µg/L action level at 18 water systems that serve a city in PurityMap’s reports. Here is what that number means, and what it does not.
The systems serving the most Americans span a wide range of Purity Scores. Size isn't a quality signal — here's what the biggest US water utilities' records actually show.
The cities at the top of our Purity Score ranking all sit at 100/100 — but a perfect score means something narrower than it sounds. Here's how to read the list.
What a low Purity Score does (and does not) tell you, and how to read our national rankings without drawing the wrong conclusion.
Journal analysis adds context; it does not replace a water-system report, source document, ranking methodology, or certified household test.