Turn on the tap and nothing comes out. Think it can't happen?
Check out Cape Town which is going to have to stop delivering water to all but emergency locations on Earth Day. It would be ironic if it weren't so alarming.
Years of drought have left them counting down the days, praying for rain, and building plans for emergency water distribution. At least they are on the coast where desalination is feasible (with associated environmental impacts, of course, depending on how they do it) but those plants won't be up and running in time. May usually starts the rainy season so they might get lucky, but brinksmanship with water is never smart.
As climate change makes weather anomalies more likely, we should all be thinking about Plan B.