Survival Tip of the Day - Water Disinfection
Cardboard and aluminum foil are unlikely tools for disinfection water until you factor in sunshine. Solar water pasteurization uses the heat of the sun to raise the temperature of water to a point where microbial pathogens are destroyed. Disease-causing organisms in water are killed by exposure to heat in a process called pasteurization. Water that has been heated to 165 degrees F is free from living microbes including Escherichia coli, Rotaviruses, Giardia and the Hepatitis-A virus.
[JWR Adds: The water need not be "held" at a boiling point for any period of time. Just make the water reach 165 degrees F, and it is done]