I have often felt after talking with people that water purification is a major weakness that many of us share. In my family, we have the capability to treat large amounts of water. We have several good-quality gravity filters and numerous smaller units.
But with all of that, I still have an ace in the hole. The WAPI stands for Water Pasteurization Indicator
This new method of water purification using solar ovens and the sun has been developed by Dr. Bob Metcalf, a professor in microbiology at California State University at Sacramento.
Water Pasteurization Indicator (WAPI) is a simple thermometer that indicates when water has reached pasteurization temperature and is safe to consume. Pasteurization destroys all microorganisms that cause diseases from drinking contaminated water. The WAPI consists of a small polycarbonate tube that contains a soy wax that melts when water is heated enough to be pasteurized (65˚C/149˚F). Heating water to 149˚F kills E. coli, rotaviruses, giardia, and the hepatitis A virus. It is my understanding that the wax melts at 160°F.
Instruction on how to use a WAPI – The WAPI can be used in stoves heated with most fuels, including wood, gas, kerosene, charcoal, but it was originally designed to work with solar ovens.
Fill your container (do not use plastic) with water, place over heat or in solar oven. Place WAPI in water with the wax filled end up. To do this you have to slide the weigh so that it is on the opposite end from the wax.
This puts the wax end nearest the surface of the water. When the water reaches the correct temperature, the wax melts and falls to the bottom of the WAPI. This shows that the water has been pasteurized and is ready to drink.
Remember pasteurization does not remove dangerous chemicals. Pasteurization is not the same as sterilization and the WAPI should not be used for medical or food canning.
The WAPI can be purchased at https://www.disasterstuff.com/ for $8.00. This has to be an all time bargain for a water purification device that will last for many years and requires no maintenance or filters..