If you're talking about the water filling the streets, it's salt water and no amount of filtering can make it drinkable.

Drink fresh water that's being brought in by truck. There's more and more of it now, in insane 1/2 liter bottles. The Red Cross is getting thousands of these bottles and also thousands of 1 gallon and 2.5 gallon bottles. But they're only giving out the 1/2 liter ones, in order to keep you dependent on them, I guess. They're using the larger bottles to flush toilets with, according to a guy on CPF who visited one of their centers.