Survival Basics – Part 4: Water Purification

"Water is the driving force in nature." ― Leonardo da Vinci

As discussed in part 1's "Rule of 3's" water is vital to our survival and should be towards the top of our priority list. Do NOT wait until you are thirsty before you start looking for a water supply. The possible effects of taking that one little thirst quenching sip could severely impact your chances of survival.

So what happens if we drink untreated water straight from the source? That can depend heavily on the source (static swamp water vs running mountain spring at its source) but all should be regarded as though they require treatment prior to consumption. Water can contain protozoa like Cryptosporidium and Giardia Intestinalis causing gastrointestinal illness (cramps, vomiting, diarrhea), bacteria like Salmonella and E Coli or virus's like Rotavirus, Hepatitis A or Norovirus. The fluid loss caused by severe vomiting and diarrhea will further exacerbate our already dehydrated situation and hamper our water purification efforts. Viruses can keep our back ends busy wasting vital fluid resources for up to three days leaving us in very precarious position.

Purifying is the generic term given by us all to making our water safe to drink but there's a difference between purifying and filtering. Filters use mechanical devices, a barrier (sometimes referred to as an attractant), to capture microorganisms in the water. Their efficiency at doing so is relative to the pore size of the filter, the smaller the pore size the more microorganisms it captures and hence the better it filters. Note that filtration does NOT remove viruses from the water source. Purifiers render dangerous contaminants in the water source inactive by chemical, ultraviolet or mechanical treatment.

Here's the CDCs thoughts on what is effective against what.

From the CDC table we can see that the age old method of boiling is extremely reliable but what if we can't make fire or find a vessel to boil water in? Our next options are to filter first then add our chemical treatment (Iodine, chlorine or Chlorine dioxide) followed by chemically treat only and then filter only. That being said, groundwater in the U.S. is almost certainly virus free making filtration one of the easiest methods of obtaining potable water.

Let's take a look at the different types of water treatment systems available.

Filtration

There are three main types of water filter:

1. In-line – small, portable hollow tubes with a filter medium inside. Use them like a large straw effectually sucking the untreated water through the treatment medium.

 2. Hand pump – larger hollow tubes with a medium inside. The pumping action pulls untreated water through the treatment medium. They are bigger and heavier than in line systems but process more water faster than their smaller counterparts.

3. Gravity fed systems – produces potable water at a much slower rate and is more suited to an individual or group that is remaining in the same place. The amount of water treated is determined by the size of the feed and collection reservoirs. The military "Milbank Bag" (right) is a one-person variant of the bigger systems and is extremely compact.

  If you're caught in a situation where all of your water purification supplies are heading home with your equine "friend" you can utilize nature to assist in making a water filter. Notice there are no hard and fast rules as to the makeup of the filtering material or the container that holds it. If you have a plastic water bottle you can turn it upside down, cut the bottom off and fill it with material allowing the filtered water to drip from the lid into your container (probably your hat in this case!)

Purifiers

In compliance with each products instructions, add the required quantity to a stated amount of water and wait a predetermined period of time prior to consumption. Great for on the move.

Chemicals used mostly include iodine or chlorine dioxide and can leave the water with a bad taste. Not an issue for adults but may cause problems with smaller children refusing to drink. Not all tablets are the same so do some research to make sure you know you're getting what you think works best for you e.g. Each Aquatab tablet treats up to two quarts of water in thirty minutes but will not offer protections against Cryptosporidium while Micropur offers total protection but 1 tablet will treat one liter of water in four hours.

UV light purification

UV light can be another good lightweight option. You could have drinking water from a blast of light in as little as sixty seconds. The downside is they don't work well in murky water, they can be expensive and they're battery powered!

Boiling

The age old, tried and tested method of boiling your water. Even stagnant, debris ridden water can be filtered and the clean product boiled to purify it. Most bacteria and microorganisms cannot withstand the heat and die during the process. Ensure that your water is clean prior to boiling by removing any visible debris (twigs, leaves and soil). Filter it as well if you have the option.

If you are not in possession of a container that will withstand boiling the water, another method you can use is the hot rock method. Here we place fist sized rocks into the fire and heat them up. Using suitably sized twigs as tongs, we pick up the red hot rocks and lower them into the water. The heat from the rocks is given off into the water rapidly bringing it to the boil. Replace the rocks as necessary until you have achieved your goal.

Distillation

Distillation is the volatilization or evaporation and subsequent condensation of a liquid (think of a kettle boiling and the steam that's given off condensing back into a liquid on neighboring surfaces). The next illustration should provide the basic concept and also works with saltwater.

If you don't have suitable containers for boiling water or don't have fire, it's possible to use the power of the sun and make a solar still. It works in the same way but takes longer to achieve the same objective. In general, you create a moisture rich hole over which you secure a piece of plastic (the one your equine "friend" escaped from) placing a small weight on top to create a low point that the moisture will run to and drip from into your container. The hole could quite simply be a damp hole, you can pull up and add plants that will give off moisture or you could place a container of dirty water in there to increase the moisture level and assist the process.

The method you choose will likely depend on a combination of the equipment you have available to you, the type of water source and your level of comfort with regards to the safety of the water. You can take the chance of drinking the water straight from the source and risk getting sick versus dying from dehydration but the preference would always be to equip yourself with the knowledge and equipment to survive without running that risk.

"Thousands have lived without love, not one without water." - W. H. Auden