According to the EPA, if you can’t boil water, you can disinfect it using household bleach. Do not use non-chlorine bleach to disinfect water. Typically, household chlorine bleaches will be 5.25% available chlorine. Bleach will kill some, but not all, types of disease-causing organisms that may be in the water. If the water is cloudy, filter it through clean cloths or allow it to settle, and draw off the clear water for disinfection. Add 1/8 teaspoon (or 8 drops) of regular, unscented, liquid household bleach for each gallon of water, stir it well and let it stand for 30 minutes before you use it. Store disinfected water in clean containers with covers. There are two big disadvantages of treating water with chemicals. First chlorine can be potentially dangerous if used improperly and it may not be readily available when you need it. A safer product is ION. It is a non-toxic, stabilized oxygen liquid that is added to stored water and reportedly kills pathogenic bacteria. However, it is not readily available in most stores. But there is a safe chemical free option, inexpensive option for disinfecting your water.
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 65ºC (149ºF) for a short period of time is free from microbes including Escherichia coli, Rotaviruses, Giardia and the Hepatitis A virus.
Although traditional fuels can be used to pasteurize water, on sunny days solar energy is the better choice. A major problem with boiling water for disinfection is its energy consumption in relation to cost and availability of the fuel supply. If you do not have electricity you do not want to spend all of you fuel supply sanitizing your water. Boiling water for five to ten minutes takes a lot of fuel.
With full sunshine, it takes about 2 hours to pasteurize 2 liters of water. In order to determine when water has reached pasteurization you will need to invest in a simple device called a WAPI (Water Pasteurization Indicator). The WAPI is a simple reusable device containing a special soy wax. The wax melts at the same temperature as the water is pasteurized. The tube hangs on a string inside the container with the wax end up, and once the water around it becomes hot enough to kill the bacteria the wax melts, running from the top part of the tube to the lower end. Although it is designed for solar pasteurization, the WAPI can be used for pasteurizing over most fuel sources including gas, wood, and charcoal. WAPI’s generally cost between $5 and $10.
Solar water disinfection is also known as SODIS. The SODIS process involves filling clean PET (Polyethylene Terephtalate) transparent plastic bottles with water and exposing them to full sunlight for six or more hours. The combination of UV-A radiation and raised water temperature disinfects the water. There are a few drawbacks to this method. SODIS efficiency depends on the physical condition of the plastic bottles, with scratches reducing the efficiency of SODIS. Leaching of bottle material. There has been some concern over the question whether plastic drinking containers can release chemicals or toxic components into water, a process possibly accelerated by heat. A solar cooker will make the process more efficient.
While pasteurizing will solve a lot of disease problems, it does not remove other things found in the water such as chemicals, pesticides and heavy metals.
You can purchase elaborate solar cookers or build one using simple materials. You can find a large number of solar cooker building plans at http://solarcooking.org/plans. I have included instructions for a simple windshield shade solar cooker at the end of this article. I have also included instructions from Needful Provision, Inc. on how to construct a simple solar water-distilling unit.
Building and testing a solar cooker also makes an excellent school science project. The last project I worked on with my child was, “Can you bake cookies in a solar oven in North Carolina in the month of January?” The conclusion was yes. Solar cookers should certainly be one the items at the top of the list for TEOTWAWKI. They are portable, use only the sun as an energy source and they work!
”KEEP CALM AND CARRY ON”
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