I know I seem to be perseverating about water and making it a big deal in one’s emergency planning. But according to the World Health Organization 80 % of the illnesses of the world are spread through contaminated water. Heating water to 65 degrees centigrade or 149 degrees Fahrenheit makes it free from disease organisms making it safe to drink. This process is called Pasteurization. Water stays safe to drink if it is kept in sealed containers after pasteurization.
If you put a WAPI (water pasteurization indicator) in water when you heat it, it tells you if the water has been pasteurized, even if the water has already been cooled. The WAPI is a sealed tube with special soy way inside that melts at 65 degrees centigrade or 149 degrees Fahrenheit. Melting of the wax is actually a bit above pasteurizing temperatures after the heat penetrates the tube.
The WAPI is also ideal for use with a solar oven. First, adjust the WAPI so the long string and the wax are at the tope of the tube and one washer is at the empty bottom of the tube. Hold the string and place the WAPI into the water so it touches the bottom center of the container. Keep one end of the long string outside the container to lift the WAPI out later. The washer weighs down the empty end of the tube in the water. When the water gets hot enough to melt the wax the water has been pasteurized. The wax will run to the bottom of the tube (by the washer).
Even if the water cools before you check it, if the wax is at the bottom by the washer the water is safe. If the wax is still at the top the water is not yet pasteurized.
IMPORTANT: After the water is pasteurized, cover with a lid and don’t put anything into the water that could re-contaminate it. Lift the WAPI out of the water by the string and keep it clean.
With a solar oven use thin-walled metal or glass containers painted black outside. Put a loose lid on the container so all stream wont escape, then put in solar oven. On a good sunny day 4 liters will take about 4 hours in a solar oven. You can decrease your pasteurization time by using a larger solar oven, using several small containers rather than a large one, and pasteurize the waster in the middle of the day and on a full sunny day with no clouds or dusty wind.
This is an easy, reusable, low cost and safe method to pasteurize your water needs during emergency situations.
All information was taken directly from WAPI information sheet to ensure proper communication of the information.