What H2Oh! can tell you — and what it can’t
Last updated 14 September 2026
H2Oh! has never tested your water. Every figure on this site comes from a public record filed by a water utility with the EPA or a state agency. We collect those records, simplify them, and score them. We do not take samples, run laboratory analysis, inspect homes, or make regulatory determinations.
A WaterScore is not a safety verdict. It summarises a utility’s reported compliance history — violations, enforcement actions, missed tests. A high score means a utility has a strong record of meeting federal requirements. It is not a promise about any single glass of water. A low score means there are reported compliance problems worth understanding. It does not mean the water is immediately dangerous.
Verify anything that matters. Before you act on something you read here, confirm it with your water utility, your state or local health department, a state-certified laboratory, or the original record we link to.
In an emergency, do not use this website. Follow the instructions of your utility and local authorities. H2Oh! is not an emergency service and can be hours or days behind a local announcement.
Where the numbers come from
Nothing here is our measurement. Here is the actual chain of custody for a figure on a city report:
| Step | Who does it |
|---|---|
| Water is sampled and analysed | The utility, using laboratories certified under state and federal programmes |
| Results and violations are reported | The utility, to its state primacy agency and to the EPA |
| Records are published | EPA (SDWIS, Lead & Copper Rule, enforcement actions) and state agencies |
| Records are collected, arranged, weighted and scored | H2Oh! — this is the only step that is ours |
| Plain-language explanations are written | H2Oh! — our interpretation, not the agency’s wording |
Wherever a report shows a figure, we try to show the source and a link to the original record beside it. If you ever see a number on this site without a source, treat it with suspicion and please tell us.
What the data cannot tell you
- What is in the water at your tap. Public records describe what leaves the treatment plant and what a sample of homes measured. The pipes in your street, your service line, and your own building’s plumbing all change what arrives at your faucet. A building with lead service lines can have lead problems in a city with an excellent score. Only a test at your tap can tell you about your tap.
- What is happening right now. EPA violation records are typically refreshed every 30 to 90 days. Lead and copper results can be one to three years old, because that is the required sampling frequency. Boil-water notices can reach a federal or state database a day or more after a utility has told its own residents. We also cache records for up to 24 hours.
- Everything that is in your water. A compliance record shows regulated contaminants that were measured and reported. Unregulated substances, and substances nobody was required to test for, do not appear.
- PFAS. We do not currently score PFAS for any city, because the EPA publishes that monitoring data only as bulk downloads with no live feed we can use. Where PFAS appears on a report we say what data we lack. No PFAS result on H2Oh! should be read as evidence that PFAS is absent — it means we do not know.
- Private wells. Wells are not regulated under the Safe Drinking Water Act and do not appear in these records at all. If you are on a well, testing is on you. The CDC’s private well guidance is the place to start.
- Whether a missing violation means a clean record. No reported violations can mean a system is genuinely clean — or that it did not report. We treat missing data as missing, never as a pass.
How we use standards, and who owns them
When we compare a measurement to a limit, the limit belongs to a regulator or a standards body, never to us. We name it every time so you can check it yourself:
| Measure | Standard | Set by |
|---|---|---|
| Lead | Action level of 15 parts per billion at the 90th percentile of sampled taps | EPA, Lead and Copper Rule |
| Copper | Action level of 1.3 parts per million | EPA, Lead and Copper Rule |
| Total trihalomethanes (TTHM) | Maximum contaminant level of 80 µg/L | EPA |
| Haloacetic acids (HAA5) | Maximum contaminant level of 60 µg/L | EPA |
| PFOA, PFOS | Maximum contaminant level of 4 parts per trillion | EPA, April 2024 PFAS rule — not currently scored by H2Oh! |
| PFNA, PFHxS, GenX | Maximum contaminant level of 10 parts per trillion | EPA, April 2024 PFAS rule — not currently scored by H2Oh! |
| Filter performance | NSF/ANSI 42 (taste and odour), 53 (health effects, including lead), 58 (reverse osmosis) | NSF International / ANSI |
An important distinction: a legal limit is a regulatory threshold, not a line between safe and unsafe. Limits balance health science against what treatment can practically achieve. For lead in particular, the EPA and CDC state there is no known safe level of exposure — so a system can be fully compliant and lead can still be worth reducing in your own home.
And when we say a system is or is not in compliance, we are reporting what a regulator recorded. H2Oh! makes no regulatory determinations of its own and has no authority to.
Our labels are our interpretation
Letter grades, category labels, risk levels and the plain-language summaries throughout the app are H2Oh!’s editorial interpretation of public data. No agency assigns them, reviews them, or endorses them. Reasonable people could weight these factors differently and arrive at a different grade for the same city. Our weighting is published in full on the WaterScore section so you can disagree with it knowledgeably.
Not professional advice
Nothing on H2Oh! — including the Water Assistant, which is an AI feature and can be wrong — is medical, health, legal, engineering, or regulatory advice. If you have a health concern, speak to a clinician or your local health department. If you need to know what is at your tap, use a state-certified laboratory.
Who to contact instead of us
- Your water utility — the authority on your system. Ask for the current Consumer Confidence Report, which is written for residents and published annually.
- Your state drinking-water agency or health department — for advisories, enforcement, and questions about a specific system.
- EPA Safe Drinking Water Hotline — 1-800-426-4791.
- A state-certified laboratory — to test your own tap.
- Your doctor — for any health question about exposure.
- 911 or your local emergency services — in an emergency.