Why does this concern me?The further away from developed cities and regions one gets the higherthe probability that there are contaminants in water sources.There are 3 primary types of Pathogens we are trying to avoid:Protozoa – Cryptosporidium and Giardia. Hard outer cystprotects against some chemicals. Relatively large (1-20 microns)and easy to filter out.Bacteria – E. Coli, Salmonella, Campylobacter, Shigella.Midsized pathogens between .1 and 10 microns.Viruses – Hepatitis A, Rotavirus, and norovirus. These aretoo small to be filtered out, between .005 and .1 microns. Aconcern for underdeveloped countries and overcrowded areas(human waste). These need to be removed or neutralized. Notusually a concern in US and Canada. 1 micron = 1 millionth of a meter. < This period is 50 microns As few as 10 microorganisms can cause symptoms.
Filtration – physically straining out protozoan cysts and
bacteria through a filter element. This is accomplished by “sizeexclusion” but only effective down to .4 microns (viruses are too small).
Purification – this method is effective against all 3 typespathogens and can be done by chemical or UV treatment.
Factors to ConsiderFilter vs. Purifier – know what you are trying to avoid andbasic methods of avoiding it.Types of Filters and Purifiers – effort required varies, asdoes the wait time before water is ready.Know best practices – follow basic hygiene and usage guidelines.
Tips and Best Practices- Separate and clearly designate dirty and clean containers- Pay close attention to directions (cross contamination)- Seek out the cleanest water possible (murky sources)- Keep your hands clean- Gather water from the surface- Keep camp, toilet, dishwashing station areas at least200ft. from water source.All devices used to treat water (other than chemical) will have aninternal element or cartridge. Filter components utilize microscopicpores that catch debris, protozoa, and bacteria. Many filters andpurifiers will use an “activated carbon” element that is effective atremoving unpleasant taste (leaf tannins) and reduces contaminants likepesticides and industrial chemicals.Pre-Filter – a pre-filter removes large particles before they reachthe main filter/purifying element. Although natural particles pose nohealth risk they can affect the ease of the process, frequency ofmaintenance, and the lifespan of the element. A pre-filter is a greataccessory when dealing with murky water (leaf debris, mud, silt,sediment).Improves treatment process and flow rate as well as improvingeffectiveness of chemical treatmentEssential prior to UV treatment of unclean waterTypes of Filters-Pump Filters:
Pros: precise output, access to shallow sources, element is replaceable.
Cons: pumping sucks, field cleaning required, heavier and bulkier than other options.
Pros: gravity does all the work, large output, element is replaceable.
Cons: hanging can be tricky, slower process, shallow source can be a challenge, field cleaning required.
Bottle Filters/Purifiers:Pros: easy & quick, element is replaceable, lighter & cheaperCons: quantity is limited to bottle size, field cleaning required
Squeeze Filters:Pros: easy & quick, element is replaceable, can double as a gravity or straw style, lighter, smaller, and cheaper.Cons: quantity is limited to vessel size, field cleaning required.
Straw Style:Pros: quick & easy, lighter, cheaperCons: must be at water source, 1 person option, cleaning, and not all elements are replaceable.
Types of PurifiersUV Purifier: disrupts DNA so the pathogen cannot reproduce,therefore not cause illness. Pre-filter is highly recommended.
Pros: easy & quick process, no element cleaningCons: batteries, water quality impairs treatment, pre-filtration required, and multiple treatments for large groups.
Chemical Purification– this treatment method is effectiveagainst all pathogens and usually iodine or chlorine based. Can be drops,pills, or gadgets that mix base chemicals.Pros: easy use, very inexpensive, small and very light, great backup method.Cons: wait time (up to 4 hours), taste (iodine), Iodine is noteffective against Cryptosporidium and a concern for pregnant womenand those with thyroid issues.
Boiling – combats everything. Bring to rolling boil for 1 minute, 3minutes if above 6,500 ft.Pros: water quality not a factor, readily available backupCons: time and effort, wait time (cooling), need extra fuel.
Common Filters and PurifiersFilters: MSR MIniWorksMSR Trail ShotSawyer SqweezeSawyer MiniKatadyn HikerKatadyn VarioKatadyn Hiker ProKatadyn BeFreeLifestrawPlatapus Gravity Filter