A normally active person needs to drink at least two quarts of water each day. Hot environments and intense physical activity can double that amount. Children, nursing mothers, and ill people will need more. Store your three-day supply in a handy place. You need to have water packed and ready in case there is no time to fill water bottles when disaster strikes.
Water needs to be treated only if it is of questionable purity.
Boiling is the safest method of treating water. Strain water through a clean cloth to remove bulk impurities. Bring water to a rolling boil for about one full minute, keeping in mind that some water will evaporate. Let the water cool before drinking. Boiled water will taste better if you put oxygen back into it by pouring the water back and forth between two clean containers.