Water is essential for human life and unfortunately some sources provide water unsafe for human consumption. There are several methods for treating water including osmosis, distillation, ultra violet, boiling, filtering, and chemicals such as chlorine or iodine. Most of these treatments are aimed at biological contamination and each of them has disadvantages in a WTSHTF scenario. My solution is to first pre-filter the water using coffee filters or a clean rag, then use a quality microfilter such as the Katadyn Pocket filter, and then boil or chemical treat the water as the situation allows. In this article we will briefly examine biological contaminates and why I came to my solution. Contaminates may also include chemicals but is beyond the scope of this article.
Biological contaminates consist of microorganisms also called microbes. There are four different groups. Arranged from largest to smallest they are, fungi, protista, bacteria, and viruses. The smallest bacteria which causes human disease is Mycoplasma pneumoniae which is approximately 0.2 microns in size. When selecting a microfilter, I want one that filters down to at least 0.2 microns (a micron is one micrometer or 0.000001 meter or 1 x 10-6 meter). While effective against bacteria and larger microorganisms, even a good microfilters (0.2 microns) can not be counted on to filter out viruses unless there is another mechanism to trap or destroy the virus. All the viruses I am familiar with are smaller in diameter than 0.3 microns, examples include Smallpox 0.250 microns, Rabies 0.150 microns, Influenza (Flu) 0.100 microns, and Polio 0.028 microns. Viruses are composed of DNA or RNA surrounded by a protein coat called a capsid. This construction allows them to be easily destroyed by boiling or chemicals such as iodine or bleach. While iodine or bleach is effective against viruses, it is ineffective against the protista Cryptosporidium. Since the first recorded human case of Cryptosporidiosis in 1976, it has grown to become one of the most common waterborne diseases. Rates from 6%, to as high as 54% have been found in day care centers in the United States. In 1993, an outbreak in Milwaukee, Wisconsin infected approximately 400,000 residents. 4,400 people had to be hospitalized and the cost of the outbreak was estimated at over $54 million. If this is a problem now, imagine what it would be in WTSHTF scenario. See the CDC web site for additional information. What about boiling water to kill microbes? Unfortunately, some bacteria produce spores (also called endospores) which can survive extreme conditions. They can survive being boiled in water (100 degrees Celsius) for two hours, survive in 70% ethyl alcohol for 20 years, or survive one million REMs ([just] 600 REMs is fatal to most people). One of the most infamous bacteria that forms spores is Bacillus anthracis which causes Anthrax. By using a microfilter, I am eliminating fungi, protista, bacteria including spores and leaving only viruses that can easily be destroyed with chemicals or by boiling.
I came across another product called “First Need Portable Water Purifier” that is supposed to remove viruses without any chemicals. I have no experience with this product but will be checking it out. See their web site for more information. – Bill N.