Ninja,

Welcome to the fire and that's a very good question. As others have mentioned water collected from your roof should be easily treatable assuming you aren't in a heavily polluted area (say, China). As for the sump-pump, even that could be treated mith the right sorts of filters. Make sure they have some activated charcoal to catch chemicals.

Depending on the space, time and money you have a system like this sand filtration unit used in refugee camps might be your ticket.

-Blast