How safe is U.S. tap water?
U.S. public drinking water is heavily regulated — but safety is uneven. This is the national picture, drawn directly from the EPA's Safe Drinking Water Act compliance records, with the tools to check your own city.
Source: EPA Safe Drinking Water Information System (SDWIS) · 2026 Q1 · health-based violations since 2016
The most common contaminants
Lead
5,736systems with violations
Lead leaches from old pipes and fixtures, not the source water — which is why it varies house to house and why service-line replacement is the real fix.
Disinfection byproducts
4,670systems with violations
The trade-off of disinfection itself: chlorine kills pathogens but forms cancer-linked byproducts, making DBPs one of the most widespread health-based violations.
Bacteria & coliform
2,462systems with violations
Coliform is the early-warning indicator that something could let pathogens into the water — the trigger behind most boil-water notices.
Radionuclides
791systems with violations
Naturally radioactive elements that seep from rock into groundwater; a geology-driven, region-specific cancer risk.
Arsenic
714systems with violations
A naturally occurring carcinogen in many groundwater systems; the fix is treatment, since you can't avoid the geology.
Nitrate
636systems with violations
An agricultural contaminant that's acutely dangerous to infants; common across farm country and rural groundwater.
Where violations cluster
Share of community water systems with a health-based violation since 2016.
Dig into the rankings
Texas leads "States With the Most Drinking-Water Violations" at 1,723 systems.
States With the Safest Community Tap WaterHawaii leads "States With the Safest Community Tap Water" at 6%.
States With the Most Lead Action-Level ExceedancesPennsylvania leads "States With the Most Lead Action-Level Exceedances" at 390 systems.
The Most Drought-Stricken States Right NowDelaware leads "The Most Drought-Stricken States Right Now" at 100%.
Common questions
Is U.S. tap water safe to drink?
For most Americans, yes — U.S. public drinking water is among the most regulated in the world. But the picture is uneven: of 48,769 community water systems serving about 330 million people, 14,233 (29%) have had at least one health-based Safe Drinking Water Act violation since 2016. Risk is concentrated in smaller systems and specific regions.
How do I find out if my city's water is safe?
Look up your state and city profile for the local water systems, their violations, and lead levels, then read your utility's annual Consumer Confidence Report (CCR), which every community water system must publish each year.
What are the most common drinking-water problems?
The most frequent health-based violations involve lead and copper, disinfection byproducts (TTHM and HAA5), coliform bacteria, the Groundwater Rule, and naturally occurring contaminants like arsenic, nitrate, and radionuclides.