Your tap water has a story.We translate it.
Every public water system in America has to report its test results to the EPA. H2Oh! reads those reports for 302 cities and turns them into one clear score.
A strong record of following federal rules, with few violations in the categories we track. Every signal below is explained in plain words.
Out of all the homes tested here, the highest readings still came in under the EPA’s limit of 15 parts per billion.
No reported E. coli or other bacteria, and no failures in how the water is treated.
No fines or formal legal orders from the EPA or the state.
The EPA doesn’t release this data in a form we can pull automatically. We leave PFAS out of the score rather than assume it is safe.
A real example, captured August 2026.
The data is public. It’s just hard to read.
These records are written for regulators and engineers, not for the people drinking the water.
Put into one format, weighted, explained and scored the same way every time.
One score. Multiple signals.
We score several things separately, then combine them into one number. Each one counts for a set share of the total. Every city is scored the same way, so two cities with the same record get the same score.
Germs in the water: E. coli, coliform bacteria, Giardia, Cryptosporidium and Legionella, plus cloudy water and failures in how the water is treated. Anything that could make people sick counts as a serious failure.
Tap water samples from the last two years, where they exist, compared to the EPA’s limit of 15 parts per billion. If a system has no samples on record we leave it out, rather than assume the water is clean.
Times the water went over the legal limit for a contaminant. Recent ones count more, and more dangerous contaminants count more.
PFAS are long-lasting industrial chemicals. We would compare PFOA and PFOS to a limit of 4 parts per trillion, and PFNA, PFHxS and GenX to 10 parts per trillion. The EPA only publishes this data as large downloads with no way to pull it automatically, so this factor scores nothing today and its share is spread across the others.
Tests the system was required to run but missed or filed late. A missed test means a problem could go unnoticed, so it lowers the score even when nothing was found.
Chemicals left behind when water is treated with chlorine. Only going over the legal limit lowers the score. Missing a test here does not.
Official action taken against the utility by the EPA or the state, such as legal orders or fines. Recent action counts more.
If there is an active notice telling people to boil their water, this factor scores zero. We check the Florida and Georgia health departments, EPA enforcement records and National Weather Service alerts.
Whether the utility told residents about problems on time. We track it and show it, but keep it out of the score so the same failure is not counted twice.
Recent problems count more
Older violations count for less over time. Serious contaminants like E. coli, nitrate, arsenic and lead count for more than minor ones.
Size is accounted for
Large utilities run more tests, so they naturally record more violations. We compare the number of violations to the number of homes served. Big systems aren’t punished for being big.
Missing data isn’t treated as good news
When we have no data for something, we leave it out and spread its share across the rest. We never treat missing data as a pass.
Compliance is a floor, not a guarantee
A high WaterScore means the system met the federal rules for testing, treating and reporting its water. That matters. It is still not a promise about any single glass of water.
A note on what this measures. H2Oh! shows what your public water system reported. Your own home can be different. The pipes inside your house, the line running to it and the age of the building all change what comes out of your tap.
Know. Understand. Act.
Data on its own changes nothing. H2Oh! takes you from a number, to what it means, to what to do.
What has been reported
What your water system has actually reported to regulators.
- WaterScore and A–F grade
- Reported violations by category
- Lead & copper sample results
What the numbers mean
What each measurement means, and who it matters most for.
- Plain explanations of each contaminant
- Guidance for children, pregnancy and older adults
- Available in English and Spanish
What you can do
Next steps that match the situation, which is often nothing at all.
- Filters that match the contaminants found, and the NSF/ANSI certification to look for
- When independent tap testing is worth it
- Alerts when a notice is issued for your area
How does your city’s water compare?
A score means more when you can compare it. Every city we cover is ranked against the others in its state.
Ranking is a starting question, not a verdict.
A city near the bottom usually has one specific reason why. The ranking points you to it. The report explains it.
Find my cityWater information shouldn’t be this hard to explain.
H2Oh! is exploring how its data and plain-language reports could help utilities, researchers and partners.
Areas we’re exploring
- 01 Explaining water quality to residents
- 02 Comparing systems and regions
- 03 Pulling public data into one place
- 04 Spotting trends in water quality
- 05 Data and API partnerships
- 06 Helping utilities reach residents
These are areas we are exploring, not products you can buy today.