Learn About Your Tap Water

Learn how to read water reports, understand EPA standards, and make informed decisions about your tap water.

39 articles

Deep-dives on specific water contaminants including lead, PFAS, arsenic, and more. Learn about health effects and removal methods.

4 articles

NSF certification explained, filter comparisons, and expert recommendations for removing specific contaminants.

11 articles

City-specific water quality analysis, contamination issues, and local recommendations.

5 articles

Home test kits, certified lab reviews, and guidance on when and how to test your tap water.

0 articles

An MCL is the enforceable legal limit your utility must meet; an MCLG is the non-enforceable health goal set with a margin of safety. They're often different numbers — for arsenic the legal limit is 10 ppb while the health goal is zero — which is why "meets EPA standards" means compliant, not risk-free.

Pediatric and public-health guidance tracks the health goal (MCLG), not the legal limit (MCL). The EPA set the 10 mg/L nitrate limit specifically to protect infants under six months — there the limit is the pediatric limit — while for carcinogens like arsenic, health-only goals sit far below the legal limit.

An NSF/ANSI certification verifies a filter cuts a contaminant from a fixed challenge concentration down to a pass threshold — NSF 53 takes lead from 150 ppb to ≤ 5 ppb. That pass level is chosen for repeatable testing, not the health-goal MCLG of zero, so 'certified to reduce' isn't 'reduced to the health goal.'

Four layers protect your child's tap — EPA, your state, and your utility — but the chain stops at your property line, and infants on mixed formula can get 40-60% of their lead exposure from water (EPA, 2024).

The EPA writes national rules for more than 90 contaminants, your state enforces them and can go stricter, your utility treats and tests the water to your property line, the FDA governs bottled water — and your home's pipes and any private well are on you.

Nothing official. EPA does not test, certify, or endorse home water-treatment units, and says so in plain text (EPA, 2005). The mark that actually proves a filter reduces lead is third-party certification to NSF/ANSI 53 — not anything with "EPA" in it.