Drinking water may not be available or safe to use, particularly after floods, which can contaminate well water with chemicals, human sewage, and livestock waste.
You should only use bottled, boiled, or treated water for drinking, cooking, and personal hygiene.
The best way to make water safer is by boiling it, which will kill disease-causing bacteria and parasites. If boiling isn't possible, you can use a disinfectant like unscented household chlorine bleach, iodine, or chlorine dioxide tablets.
Keep in mind that water contaminated with toxic chemicals won't ever become safe to use through boiling or the application of disinfectants.