A good source of information about emergency water supplies and disinfect ion is found on the Washington State Health Department web site.
Drinking Water Emergencies
At this link you will find both facts sheets and publications related to emergency water supplies and water treatment. Some additional short-cuts are provided below:
Flood advice for drinking water systems
Floods (includes instructions for disinfecting drinking water and wells)
Drinking Water for Emergency Use (pdf)
Truck Transportation Guidelines: Emergency Water Supply for Public Use