U.S. water quality by state

State hubs collect the headline water-quality figures for major utilities, link out to city-level guides, and suggest the type of whole-house treatment that fits the local water profile.

U.S. water quality is not uniform. The Mountain West and Southwest run hard and high in chromium-6 and arsenic from the underlying geology. The Gulf Coast and Florida deal with sulfur, color, and disinfection byproducts. The Great Lakes region is comparatively soft but still flags lead service lines in older housing stock. The Northeast and Mid-Atlantic have aging infrastructure and growing PFAS detections. Every utility on these pages meets the federal EPA legal limits. The flagged contaminants are values sitting above EWG's stricter, non-enforceable health guideline, which is the benchmark most home-treatment decisions are made against.

Start with your state, then drill down to your city. If your city is not yet listed, the nearest metro inside the same state is usually a reasonable proxy because regional source water and treatment plants tend to be shared.

• AZArizonaAn estimated 6M+ residents affected by contamination. Up to 670 utilities reported elevated nitrate, arsenic and chromium-6.
• CACaliforniaMixed surface and groundwater across regions; chromium-6, nitrate and arsenic are recurring concerns, particularly in Central Valley agricultural areas.
• FLFloridaHard water and disinfection byproducts are widespread; aquifer-fed utilities commonly test for elevated hardness and TTHM.
• ILIllinoisLake Michigan supplies most of northern Illinois with soft–moderate water; lead service lines remain a concern in older Chicago-area homes.
• INIndianaLimestone aquifers produce some of the hardest water in the Midwest; many utilities serve water at 12+ gpg.
• MNMinnesotaSurface and groundwater are typically very hard; Mississippi-fed utilities also test for nitrate.
• MOMissouriMixed surface and limestone-aquifer sources; hardness is the main issue for most households.
• NENebraskaAgricultural runoff drives nitrate concerns in many Nebraska utilities; some surface systems also see elevated TTHM.
• NVNevadaMost population served by Colorado River water via Lake Mead. Arsenic and chromium-6 are recurring concerns in groundwater-served communities.
• NYNew YorkCatskill / Delaware surface water serves NYC; older buildings statewide still have legacy lead service lines.
• PAPennsylvaniaRanks among the most contaminated states. About 19% of tested systems had PFAS above the EPA standard; USGS found PFAS in 76% of sampled PA rivers and streams.
• TXTexasUp to 207 contaminants detected statewide. Over 700 water systems reported TTHM above the EPA legal limit of 80 ppb, reaching an estimated 8.6M people.
• UTUtahMountain snowmelt and groundwater produce hard water in most Wasatch Front communities.