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See every US state's tap water grade A–F from EPA data — then compare any two cities side-by-side: contaminants detected, EPA violations, safety scores & a personalized filter pick. Free, no signup.
206+ city-to-city comparisons available
Compare water quality between the largest US cities
Compare water quality between cities in the same state
Compare water quality between neighboring cities and regions
Common relocation routes - compare water quality before you move
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Our water quality comparison tool lets you see side-by-side differences between any two US cities. Each comparison includes:
All data is sourced from the EPA's Safe Drinking Water Information System (SDWIS) and updated quarterly.
Whether you're considering a move, curious about how your city stacks up, or want to make informed decisions about water filtration, our comparison tool gives you objective, data-driven insights. Understanding water quality differences can help you:
Pick any two US cities and our comparison tool shows their water side-by-side: overall A–F safety grades, detected contaminant levels as a percent of EPA limits, EPA violation history, infrastructure age, and which city has better water in each category. All figures come from the EPA Safe Drinking Water Information System (SDWIS) and are updated quarterly.
Each city receives a 0–100 score and a corresponding A+ to F letter grade based on three weighted factors: how far detected contaminants sit below EPA maximum limits, the city’s EPA compliance and violation record, and the age and condition of its distribution infrastructure. Cities with protected source water, modern treatment, and no recent violations score highest.
State rankings aggregate the scores of the public water systems within each state, so states where most cities have low contaminant levels and clean EPA compliance records rank near the top. Because water systems are managed locally, quality can still vary widely between cities in the same state — always check your specific city for the most accurate picture.
The cleanest tap water is usually found in cities with protected aquifers or reservoirs, modern treatment plants, and no lead service lines — these earn A and A+ grades. Cities with aging infrastructure, industrial contamination, or repeated EPA violations score D or F. See our Best Water Quality and Worst Water Quality rankings for the current city-by-city lists.
Yes. Each comparison highlights the specific contaminants detected in each city, so you can match a filter to the actual problem — for example reverse osmosis for arsenic, fluoride, or PFAS, or an activated-carbon pitcher for chlorine taste and odor. Our Water Filter Guide pairs the most common contaminants with proven filtration methods.