For all who use portable water filtration whether from Katadyn or Aquamira, a coffee filter around the intake will greatly extend internal filter life. Extended water filter life is paramount in any survival situation. All of my portable filtration is stored with multiple coffee filters. Water filtration is not necessary everywhere but given our population density, is always a ‘best practice’.
The following excerpt is from the excellent 13,000 gallon Katadyn pocket filter (http://shop.katadyn.
com/product/153548/8013618/_/ Katadyn_Pocket) manual (my favorite filter):
“Ceramic capacity depends on water quality. The dirtier the water the more often you will have to clean the element. This reduces the capacity of approx. 13’000 gallons (50’000 liters). If the gap of the measuring gauge fits over the ceramic it is time to replace the filter element. (Figure 2-2) Inspect the ceramic for cracks after cleaning, if you dropped the filter or if you had freezing temperatures. If the filterelement shows cracks it will no longer protect you from microorganisms and must be replaced.”
For this Katadyn pocket filter with remote intake, I secure the coffee filter pre-filter around the intake pre-filter with a rubber band and drop into the water source. I like this unit because of its 0.2 micron filtration, excellent design and packaging including small size, long filtration life, ability to quantitatively determine when the element needs to be replaced, availability of spares, remote pick up, and of course excellent reputation of the Swiss manufacturer. The disadvantage to all of this engineering is price which is in the low $300 range. My wife’s ruck is equipped with the Katadyn Vario. This unit is 1/3 the cost of the pocket filter and is rated at only 100 gallons or so. She liked the pump lever design and direct connection to water bottles or bladders. This unit also comes with remote pickup, pre-filter, and bottle clip but is much more complex mechanically than the Katadyn pocket model (more parts to break) and is made of plastic (which is known to break).
Ideally, one would draw contaminated water into a transparent container and wait 24 hours or so for gravity filtration of contaminants and sunlight UV sterilization of any biological component. The coffee filter protected water filter intake would then be applied to the top of any water thus treated. In other than a fixed camp this is an impossibility so I just use the coffee filter pre-filter to remove the largest dissolved solids from whatever body of water I tap.
For units that depend upon a ceramic filter, a wet filter then frozen may develop cracks from the trapped and ice expanded water. Wet filters subjected to freezing temperatures that develop cracks should no longer be relied upon for potable water. Body heat can be used to keep the filter from freezing but the filtration unit itself would have to be kept in contact with the body, perhaps under a shirt layer.
Filtration straws indeed have their place but more perhaps more as a real emergency backup to expedition quality filters. I recommend securing a dozen or so coffee filters around the intake of whatever filtration device(s) you might have with a rubber band and covering the whole thing with aluminum foil. For use, I carefully remove the foil and separate the outside filter. I begin use with this most outside coffee filter, discard, and for the next use, the filter below it, working my way per use from the outside toward the most innermost coffee filter, carefully replacing the aluminum foil between uses. The reason for this sequence is that the outside filter would likely be the first to become environmentally contaminated.
My first Katadyn pocket filter was bought for a Kodiak brown bear hunt. I flew my single engine airplane from Texas to the Alaskan mainland Kodiac island region on what turned out to be a several month wandering round trip of about 6000nm total duration, much of which was flown over uninhabited and remote areas.
For the transit of Canada, their flight rules required an emergency kit in the airplane, whose contents I reproduce below if for no other reasons than for comparison with the contents of your cold weather ruck and to score a point mentioned in para 1 above.
“1. Canadian required emergency equipment includes:
- food having a calorific value of at least 10,000 calories per person carried, not subject to deterioration by heat or cold and stored in a sealed waterproof container bearing a tag or label on which the operator of the aircraft or his representative has certified the amount and satisfactory condition of the food in the container following an inspection made not more than six months prior to the flight
- cooking utensils
- matches in a waterproof container
- a stove and a supply of fuel or a self-contained means of providing heat for cooking when operating north of the tree line
- a portable compass
- an axe of at least 2 ½ lbs or one kilogram weight with a handle of not less than 28 inches or 70 centimeters in length
- a flexible saw blade or equivalent cutting tool
- snare wire of at least 30 feet and instructions for use
- fishing equipment including still fishing bait and a gill net of not more than a 2 inch mesh
- mosquito nets or netting and insect repellant sufficient to meet the needs of all persons carried when operating in an area where insects are likely to be hazardous
- tents or engine and wing covers of suitable design and color, or having panels colored in international orange or other high visibility color, sufficient to accommodate all persons carried when operating north of the tree line
- winter sleeping bags sufficient in quantity to accommodate all persons carried when operating in an area where the mean daily temperature is likely to be 7 degrees C or less
- two pairs of snow shoes when operating in areas where the ground snow cover is likely to be 12 inches or more
- a signaling mirror
- at least 3 pyrotechnic distress signals
- a sharp jackknife or hunting knife of good quality
- a suitable survival instruction manual
- a conspicuity panel
Further to the equipment above, the following additional items are suggested:
- spare axe handle
- honing stone or file
- ice chisel
- snow knife or snow saw-knife
- snow shovel
- flashlight with spare bulbs and batteries
- a pack sack
- firearms are carried at the operators discretion
Note: However, if it is proposed to carry firearms in an aircraft as additional emergency equipment the operator should be aware that hand held pistols, revolvers, etc., known as small arms, and fully automatic weapons are not authorized to be carried or worn in Canada. (Know this and the remainder of this regulation thoroughly before entering Canada with a firearm.)
The above information is excerpted from the 8/8/2002 issue of the Alaska Supplement published by the U.S. DOT, FAA and the National Aeronautical Charting Office. www.naco.faa.gov The Alaska Supplement is the Alaska version of the Airport Facility Directory (A/FD) which is printed for the Southern 48 U.S. States. All information should be verified current and accurate by the owner/operator prior to use.”
Serious stuff, this and regulatory minimums too. If you carry a small camp axe in your ruck, have a close look at the axe specifications above. Anywhere a camp axe is carried so should be a file and stone because a dull axe is a dangerous axe. A spare handle can be whittled out of hickory or ash so I am not very worried about carrying this sort of spares, especially in forested regions.
Now imagine my surprise at what African hunters call ‘fly camp’, when my experienced partner in Alaska just dipped his canteen into a freshet and drank directly (note that there are no water filtration or purification requirements in the above regulatory minimums). We were at least 300 miles and probably 600 miles from the nearest human habitation. In the mornings I would watch small mammals riding chunks of ice down the river toward the ocean. We drank freely from our nearby stream for months with no adverse effect. Please understand I am not advocating this practice, especially in the lower 48, but mention it for those whose travels may take them far to the north. This hunt was my first experience camping in the cold and several months of living in a canvass tent in Alaska taught this flatlander much.
Buy the very best water filter you can afford and then a spare. Use it with pre-filtration and always in the clearest water available always being careful to extend filter life. Montezuma’s revenge and worse is no laughing matter, especially in a survival situation.