Thursday, July 17, 2008

Treating Suspect Water: Additional Methods

Provident Principles and Practices
© David Edwards, 2008
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PRINCIPLES: LDS leaders have asked us to obtain and lay up in store not only food but also other supplies that we may need in an emergency or a disaster so that we may live (See, for example, L. Tom Perry, General Conference, October 1995),

PRACTICES: Here, we briefly describe six additional water treatment methods and associated supplies that may help sustain life in an emergency. We do not endorse any particular product.

Solar Distillation (SD). Properly maintained swimming-pool water, if not otherwise treated, may be used for washing, cleaning, etc. However, most experts recommend against using it “as is” for drinking. But a homemade solar still ($300) purifies even swimming pool water. ~ 67% of the water is “wasted” but that can be used for bathing, etc. SD also works for brackish or turbid water.
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Reverse Osmosis (RO). Katadyn is the only company in the world that makes hand-operated RO units. RO can be used to treat many types of water. The Katadyn Survivor 35, often used by military forces and ocean adventurers, requires lots of arm power, but it can produce up to a gallon of clean fresh water per hour, even from seawater. One couple, the Butlers, survived at sea in a raft for 66 days, drinking only water treated by one of these units! Unfortunately, chlorinated water, as found in swimming pools, destroys membranes in the Survivor 35 and most other RO units; these cannot be used to treat pool water. 80-90% of water is “wasted”. These units are not cheap: ~ $1,900.00.

Condensation from Air. New machines running on electricity may condense up to several gallons of clean drinking water per day from humidity in the atmosphere, if relative humidity is sufficiently high. Relatively expensive, these machines treat air and water with filtration and/or UV light.
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MIOX. About 7” long, the MIOX Water Purifier by MSR uses 3V lithium-cell current, salt and water to electrolytically produce a solution of mixed oxidants, which is poured into water requiring treatment; it then kills viruses, bacteria, and protozoa. Unit cost is $120-140. Batteries and salt need replacement after treating 200 L water. Shelf life for batteries is 7-10 years. Salt lasts indefinitely.

Steripen Adventurer. Treating up to 1 L of water at a time, this handheld, UV-based, battery- or solar-powered device kills viruses, bacteria and protozoa in ~ 1-2 minutes. It works only with clear, non-turbid water. Unit cost: $100 (battery) or $150 (battery/solar). Battery shelf life: 7-10 years.

Solar Disinfection (SODIS). A cheap and proven technology for water treatment used worldwide, SODIS kills pathogenic viruses, bacteria, and protozoa using UV light and heat from the sun. Water is filtered through a cheesecloth or cloth and poured into clean, clear 1-L or 2-L PET bottles and set in sunlight from 6 hours (on a sunny summer day) up to 2 days (cloudy or wintry days). Bottles are placed on a reflective metal or foil surface, if possible.

Photo of sun retrieved 17 July 2008 from www.swpc.noaa.gov/primer/primer_graphics/Sun.png
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Picture of raft is clip art modified in Paint.

Photo of people using SODIS retrieved 21 June 2008 from http://en.wikipedia.org/?title=Solar_power and used under GNU license.

Additional info: See results from a Google search on Humidity Machine Water; http://solar.nmsu.edu/publications/1437ISESpaper05.pdf; www.solaqua.com/solstilbas.html#stillop; http://www.katadyn.com/; http://www.miox.com/; http://www.steripen.com/; http://www.sodis.ch/. Next: Creative Storage Spaces.