Trust center · policy
Our Data Sources
The public datasets behind every finding, and how fresh they are.
EPA SDWIS
The Safe Drinking Water Information System supplies public-water-system inventory and compliance monitoring, including lead and copper (LCR) results.
UCMR5
The fifth Unregulated Contaminant Monitoring Rule provides nationwide occurrence data for PFAS and other emerging contaminants — the basis for our PFAS findings.
Utility Consumer Confidence Reports
Annual CCRs published by utilities supply hardness, disinfectant type and additional analyte results that federal datasets do not always carry.
Census geography
Census TIGER place files resolve city and place names to the systems that serve them.
Freshness
Each finding carries its own sampling and publication dates. Where a system’s record is stale or sparse, we say so rather than filling the gap.
Responsible: PurityMap Editorial Team
This document is maintained by the PurityMap Editorial Team and updated with a visible modification date. See a discrepancy or have a question about this policy? Use the paths below.