Water Purification

While you may think any water will do in a pinch, water that is not purified may make you sick, possibly even killing you. In a survival situation, with little or no medical attention available, you need to remain as healthy as possible. A bad case of the runs is terribly uncomfortable in the best of times and potentially deadly in an emergency.  Cholera outbreaks and other illnesses during an after a flood, earthquake or other disaster are often caused by unclean drinking water.

Katadyn Vario Pump Filter

The Katadyn Pump Filter is designed to pump contaimnated water from a stream or pond through the filtration unit resulting in filtered water pumping directly into your bottle or container.

Boiling water is an excellent method for purifying running water you gather from natural sources. It doesn’t require any chemicals, or expensive equipment — all you need is a large pot and a good fire or similar heat source. Plus, a rolling boil for 20 or 30 minutes should kill common bacteria and cysts, such as giardia and cryptosporidium. One should remember that boiling water does not remove foreign contaminants such as radiation, chemicals, or heavy metals.

To remove these contaminants, you need to use a filter or distill the water.  The best way to distill water is to boil it and then capture the resulting steam and allow it to cool and condense back into water.  The devices required to do this resembles a still, and it’s quite a bit of trouble and consumes a great deal of fuel.  Using a filter is an easier, faster option.

Commercial purification/filter devices made by companies such as Katadyn are the best choices for rendering contaminated water safe. They range in size from small pump filters designed for backpackers to large filters designed for entire camps. Probably the best filtering devices for survival retreats are the model where you pour water into the top and allow it to slowly seep through the media into a reservoir on the bottom. No pumping is required. This let’s gravity do the work and the filters functions 24 hours a day.

Katadyn Drip Filter

Ideal for homes and base camps, the Katadyn Drip Filter uses gravity to purify water -- no pumping required. It can purify tens of thousands of gallons.

On the down side, most such filtering devices are expensive and have a limited capacity. Filters are good for anywhere from 200 liters for a small portable model to 20 or 30 thousands of gallons for a more expensive filter. Some filters used fiberglass and activated charcoal. Others use impregnated resin or even ceramic elements. Generally, activated charcoal removes chemicals and other toxic substances while filters remove bacteria, protozoa and, in some cases, viruses.

Chemical additives are another, often less suitable option for emergency purification. The water purification pills sold to hikers and campers have a limited shelf life, especially once the bottle has been opened. Captain Dave considers these good for the car’s emergency kit and bug out bag, but they should be rotated out and replaced every year or two. Chemical water treatments often add a taste to the water and are not ideal for long term, repetitive use.  The taste can usually be removed by adding vitamin C or a drink mix that contains Vitamin C, such as Tang.

Ideally, you should have several levels of filters ranging from camp-wide use to individual use:

  • First, you should filter any naturally gathered water through several layers of cloth to remove as much grit and dirt as possible.  This pre-filtering will extend the life of your traditional water filters and keep them from clogging.
  • Second, you should have a camp filter that is gravity fed for use in your home or retreat.
  • Third, you should have one or more portable filters that are easy to carry about and can be used to produce filtered water almost anywhere after just a few pumps.
  • Fourth, Captain Dave recommends sports-bottle type filters for bug out bags and car emergency kits.  Rather than use a pump, these have a straw-like aperture, and when you suck on the straw it draws the water through a filtration element. Captain Dave has one of these in his car survival kit and one attached to his bug out bag with a carabiner.

If you are caught unprepared and have no filtering mechanism, you can make one that is better than nothing.  The following pour-though filtering systems can be made in an emergency and will remove many contaminants.  It is not perfect, but it is better than nothing.

  1. Take a five or seven gallon pail (a 55-gallon drum can also be used for a larger scale system) and drill or punch a series of small holes on the bottom. The holes should let the water drip out, not pour through.
  2. Place several layers of cloth on the bottom of the bucket, this can be anything from material cut from a denim jacket to an old table cloth.
  3. Add a thick layer of sand (preferred) or loose dirt. This will be the main filtering element, so you should add at least half of the pail’s depth. Compact it in the bucket.
  4. Add another few layers of cloth, weighted down with a layer of gravel.
  5. Your home-made filter media should end several inches below the top of the bucket.
  6. Place another bucket or other collection device under the holes you punched on the bottom.
  7. Pour collected or gathered water into the top of your new filter system. As gravity works its magic, the water will filter through the media and drip out the bottom, into your collection device. If the water is cloudy or full of sediment (as it may for the first few uses) simply let it drop to the bottom and draw the cleaner water off the top of your collection device with a straw or tube.

(If you have a stash of activated charcoal, possibly acquired from an aquarium dealer, you can put a layer inside this filter. Place a layer of cloth above and especially below the charcoal. This will remove other contaminants and reduce any unpleasant smell or taste.)

While this system may not be the best purification method, it has been successfully used in the past. If you have no water source but a contaminated puddle, oily highway runoff or similar polluted source, the filter may be better than nothing, but it’s not a great option.

Once the system has been established and works, you must remember to change the sand or dirt regularly.

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