Our mission
Make US drinking water quality legible to the people who drink it. We translate federal compliance data, EWG health-guideline research, and utility Consumer Confidence Reports into a single letter grade per water system, with clear explanations of what’s actually in the water and what to do about it.
How we’re funded
TapWaterSafety earns affiliate commissions when readers purchase water filters through our recommended product links. We disclose this on every page that contains affiliate links. We never recommend a product based on commission rate — recommendations are matched to a utility’s specific contaminants based on third-party filter certifications.
We are not funded by, owned by, or affiliated with any water utility, filter manufacturer, government agency, or advocacy organization. We do reference data published by the EPA and EWG, but we have no formal partnership with either.
How we calculate grades
Every utility receives a score from 0 to 100, derived from a weighted formula across five components: health-guideline performance, legal compliance, high-risk contaminant presence, compliance history, and source water vulnerability. The score maps to a letter grade A through F.
The full algorithm is published on our methodology page. Anyone can verify our scores by recreating them from public data using the same formula.
Editorial standards
Every utility page is generated from regulatory data sources (EPA SDWIS, EPA ECHO, EWG Tap Water Database, utility CCRs). We do not write narrative descriptions of utilities that aren’t backed by data.
Our blog content is researched and reviewed against current peer-reviewed literature on water contaminants and filtration technology. We cite sources for health-related claims and update articles when significant new evidence emerges.
We make mistakes. When we discover them — or when readers identify them — we correct them publicly and note what changed. Methodology criticism is welcomed; we have a public dispute process documented on the methodology page.
Limitations we’re upfront about
Our scores are based on what utilities and the EPA make public. They reflect the quality of water leaving the treatment plant, not water at any specific tap. Lead, in particular, often enters water through home plumbing — your tap-level lead exposure can differ significantly from your utility’s grade.
Our data is as fresh as the public sources allow. EPA SDWIS data refreshes quarterly, EWG annually. Significant contamination events between cycles may not appear on a utility page immediately — we update urgently when alerted but cannot guarantee real-time accuracy.
For precise tap-level information about your specific home, we recommend ordering a personal water test from an EPA-certified laboratory.