Disclaimer

Scores are independent estimates for general guidance, based on public information and infrastructure analysis — not laboratory results or medical advice. Conditions vary by city, building, and season. When in doubt, filter, boil, or choose bottled water.

Not a live water-quality reading

Our scores are periodic snapshots built from published official data (WHO/UNICEF JMP, US EPA SDWIS, and French Hub’Eau). They are not real-time measurements of the water coming out of your tap right now. Conditions can change between testing cycles, and local events — a main break, a boil-water notice, construction — will not be reflected immediately.

Compliance is not the same as zero risk

A country, state, or région meeting regulatory standards can still carry localized risk. Lead, for example, commonly enters water from household service lines and plumbing even when the public supply is fully compliant. Older buildings, private wells, and rural systems may differ significantly from the headline score.

Not medical advice

Nothing here is medical advice. If you are pregnant, have a compromised immune system, are caring for an infant, or have specific health concerns, follow the guidance of a qualified medical professional and your local water authority. When in doubt, filter, boil, or choose bottled water.

How scores are built

For full transparency on data sources, time windows, and how each 0–100 score is calculated, see our methodology. Every place page also links directly to its underlying official source so you can verify the figures yourself.