Our data & methodology
How we score your water — and why you can trust it.
PurityRadar is only as good as it is transparent. Every figure traces back to a public source with a date attached. Here’s exactly where our data comes from and how the 0–100 score is built.
Reviewed by
Dr. Elena Marsh, PhD — Environmental Engineering
18 years in drinking-water treatment & public-health policy. Last review: Jun 2026.
Where our data comes from
Safe Drinking Water Information System (SDWIS)
Federal violation records, system boundaries, and the regulated contaminant limits we score against.
Consumer Confidence Reports
The annual water-quality reports utilities are required to publish, parsed for measured contaminant levels.
Groundwater & aquifer models
Regional groundwater chemistry used to model private-well risk where no public system exists.
State agency advisories
Boil-water notices and do-not-drink advisories from state primacy agencies, feeding Water Pulse.
How the 0–100 score works
A system starts at 100 and loses points as measured contaminants approach or exceed their EPA limit. Readings well below the limit barely move the score; readings at or above it carry the most weight.
Accuracy & limitations
Our scores reflect the most recent public data for a water system, which can lag real conditions and never account for your home’s own plumbing. PurityRadar is an information tool, not a certified lab result or a substitute for your utility’s official reporting. For decisions about your health, test your own tap and consult your water provider.