In preparation for emergency situations, there is a need to have a supply of stored water and the ability to disinfect that water and other sources of water that may be available. In emergencies, the main threat from drinking water for people is disease causing organisms. It is important that all water be disinfected before using when there is an uncertainty as to its purity. Stored water that has been disinfected and placed into disinfected containers does not give a person complete certainty of the absence of disease organisms when it is opened because the lids of these containers can not be sealed to prevent these organisms from entering the containers. As the temperature changes in a container, the container breathes; that is, air enters and leaves the container as the air expands and contracts with the rise and fall of the temperature. The residual chlorine in the water when it was put into a container will dissipate with time. The residual chlorine does prevent contamination only while it is present. Therefore, any stored water should treated prior to use.
Taraba, Joseph L.; Ilvento, Thomas W.; and Heaton, Linda M., "Emergency Disinfection of Drinking Water" (1990). Agricultural Engineering Extension Updates. 28.