One of the first things we learned building this site: neither the United States nor Canada maintains a single, unified “boil water advisory” list. Advisories are announced locally, so here is the honest map of where to look.
The U.S. patchwork
In the U.S., the Safe Drinking Water Act makes the water system itself responsible for notifying customers, usually within 24 hours, and states with primacy (almost all of them) enforce that duty. That means the ground truth lives with tens of thousands of local utilities. A few states publish up-to-the-minute alert data — Alaska’s DEC and Florida’s Department of Health, for example — while others post PDF lists, interactive maps, or nothing statewide at all. The EPA’s federal database captures compliance history, not minute-by-minute advisories.
The Canadian patchwork
Canada regulates drinking water provincially. Québec publishes a consolidated advisory list, Manitoba maintains official advisory maps, Nova Scotia publishes its complete advisory history, and Indigenous Services Canada tracks short- and long-term advisories in First Nations communities federally. B.C. spreads advisories across five regional health authorities. There is no single cross-country list — but the pieces are out there if you know where to look.
How this site keeps up
We gather every official alert list we could verify and refresh it automatically, so the same notice appears once — with its source — and leaves the active list as soon as the authority lifts it. Everywhere else, region pages link you straight to the authority that issues notices. If you know of an official alert page we missed, tell us and we will add it.