Pay attention to local authorities on the status of your water supply. Use only bottled or disinfected water for drinking and cooking until the public water supplies have been declared safe. The danger with tainted public supplies is from bacterial contamination that can cause severe diarrhea. Untreated diarrhea can be life-threatening. Water that you saved in bottles before the storm should be good for up to six months, if properly stored.
Proper storage means leaving no air in the container and storing in the dark.
When in doubt, disinfect it. Use disinfected or bottled water to brush your teeth and to give to pets. To prevent the spread of disease, wash your hands frequently with disinfected water and soap. Don't use water that has a dark color, an odor or contains floating material. Use water stored in the bathtub, from the pool, or from the tap to flush the toilet.