Methodology & Sources

Clear Tap exists to make drinking water information trustworthy and usable. This page explains where our information comes from and how we handle it.

Primary sources

We rely on public, primary sources rather than secondhand summaries wherever possible. Our main references include:

• US Environmental Protection Agency (EPA) for national drinking water regulations, maximum contaminant levels, and the Safe Drinking Water Act.
• US Geological Survey (USGS) for data on water resources and naturally occurring contaminants such as arsenic.
• Centers for Disease Control and Prevention (CDC) for health effects and guidance on waterborne illness, boiling, and emergencies.
• NSF and ANSI standards for what independent certification of water treatment products actually means.
• State drinking water programs and your utility’s annual Consumer Confidence Report for local data.

How we handle regulatory figures

Standards change. We date our regulatory statements and update them when rules change. For example, drinking water rules for lead and for PFAS have both been revised in recent years, and we note the current status rather than a single fixed number frozen in time. Where a rule is in transition, we say so.

How we handle data and charts

The charts on Clear Tap visualize documented regulatory thresholds and well-established milestones, not invented measurements. When we describe how contaminant levels or rules have changed over time, we describe what public records show and point you to the source. We do not fabricate datasets or precise figures.

What we do not do

We do not sell water products, accept payment for reviews, or name specific brands in exchange for compensation. Treatment guidance is given by technology and certification standard. Clear Tap is general information, not personalized engineering, legal, or medical advice. For decisions about your specific water, consult your utility, a certified laboratory, or a licensed professional.