The tap doesn't always stop all at once.
If you're on well water, your pump runs on electricity. No power means no water, even though the pipes are fine.
If you're on city water, floodwater and storm damage can get into water mains before it ever reaches your tap, even if the power never goes out.
That's why boil-water advisories follow floods and water main breaks just as often as blackouts.
Asheville was under a boil water advisory for 53 days after Hurricane Helene. Jackson, Mississippi went weeks without safe water after its treatment plant was overwhelmed. Calgary lost its water main the week before New Year's.
And sometimes there's no tap at all.
Evacuations, flooded roads, and downed power lines can put you in your car, a shelter, or outdoors with no faucet in reach, just whatever water's actually around you. The bottled water aisle empties within hours every time this happens, and most families have nothing in the house but what's already in the fridge.