US States With the Cleanest Tap Water (and the Least Safe)
In the United States, there’s no single answer to “is the tap water safe?” — it depends on your state, your city, and even your home’s pipes. Using real EPA data, here are the states with the cleanest tap water, and the ones with the most drinking-water problems.
We score each state from the EPA’s Safe Drinking Water Information System: the share of the population served by community water systems with no recent health-based violation, weighted by how many people each system serves. Higher is cleaner.
US states with the cleanest tap water
- 1Hawaii99
- 2North Dakota99
- 3Washington99
- 4Iowa97
- 5Nevada97
- 6Virginia97
- 7Delaware96
- 8Connecticut95
- 9District of Columbia95
- 10Oregon95
These states combine strong utilities with good compliance records. Most of the country scores well — US public water is tightly regulated under the Safe Drinking Water Act — but the gap between the best and worst states is real.
States with the least safe tap water
These states have a larger share of people served by systems with recent health-based violations. It doesn’t mean every tap is unsafe — it means there’s more variability, so checking your specific city matters more here.
- 1Oklahoma54
- 2Louisiana59
- 3Arizona63
- 4New Mexico64
- 5New Jersey66
- 6Maryland68
- 7Texas70
- 8West Virginia71
The catch: compliance isn’t the whole story
A state can score well and still have local risks. The biggest is lead, which typically enters water from old household service lines and plumbing — not the public supply — so it won’t show up in a state-level compliance score. If your home was built before the 1990s, run the cold tap before drinking and consider a filter certified for lead.
Check your state
See the full, population-weighted breakdown for every state on our United States page, or read how the numbers are built in our methodology.
Frequently asked questions
Which US state has the cleanest tap water?
On EPA drinking-water compliance, states like Hawaii, North Dakota, Washington and Virginia rank near the top — nearly all of their population is served by community water systems with no recent health-based violation.
Which US states have the worst tap water?
States such as Oklahoma, Louisiana, Arizona and New Mexico have a larger share of the population served by systems with recent health-based violations, which pulls their compliance scores down.
Is US tap water safe to drink?
Broadly, yes — US public tap water is among the most regulated in the world under the Safe Drinking Water Act. But safety is set locally by your utility, and older homes can add lead from service lines, so it pays to check your city and state.