In an emergency situation, the thing that most people will need right away, and the one thing that they routinely fail to to stockpile, is water. Even relatively unhealthy people can survive several days without food, but water is a basic and immediate need for everyone, and most humans can only survive for a day or two without an adequate supply. I’ll cover sourcing the water in a later article, but for now let’s assume you’ve secured some, but aren’t certain of the quality. How do you make sure that your water is safe to drink?
Boiling
The first and most common method is boiling it. This is foolproof, easy, and can be accomplished by anyone if you have a source of fuel. It works so well that, during long stretches of history, it was common to avoid water entirely and drink beer instead. Beer was safe, as we later found out, because part of the process of making beer is to boil the the beer prior to fermentation. This was done to caramelize some sugars and infuse flavors (such as hops or pine boughs) into the beer, without thought that it was actually sanitizing the liquid. It was only recently in history that this was discovered to kill microbes.
Chemical sanitizers
If you do not have time to boil, don’t have access to fuel, or don’t want to boil for whatever reason, there are a handful of chemical agents that are safe for humans in small amounts. The most common, available in almost any household, is plain old laundry bleach, often found by the brand name Clorox. The active agent in laundry bleach is sodium hypochlorite and it can kill 99.9% of bacteria, viruses, and some molds. Used sparingly, it takes only 15 minutes to disinfect water. 4 drops in a quart of water is the usual dosage, but that should be doubled for cloudy water. Also, it is very difficult for pathogens to re-infect the water treated in this fashion, so this is acceptable for short term storage as well.
Chlorine Dioxide tablets are another method, and are available in camping and outdoor stores, as well as online. Once you have them the typical shelf life is around 3-4 years, so it’s very convenient to keep on hand in case they’re needed. Ideally these would be in a first aid kit that’s stowed with your 72 hour bag, and not forgotten on a shelf in the laundry room. Keep them where you’re going to want them in an emergency situation. Similar to these are iodine tablets, but iodine is not effective against Giardia and Cryptosporidium which are very common in ponds and slow streams. Use them only as a last resort.
Filtering
Filters are usually equated with modern uses such as removing the chlorine taste from municipal water supplies. However some filters are very effective at removing microbes and producing extremely safe water. The most well known filter setup seems to the Berkey filter and others that are similar. They can be expensive, but it’s very easy to find budget setups that employ common 5 gallon buckets that are just as effective. The setup available at this link is only one example, and is advertised to be .5 micron (.2 nominal) which is surefire protection against our friends Giardia and Cryptosporidium, and should provide acceptable protection against Cholera, E. coli, and Salmonella.
While bucket setups are great for sheltering in place, they don’t help much if you’re on the move. In that case you want portable filters that meet your needs, and there loads of choices available. You can find these in camping and outdoor stores, as well as online. Those preferring to travel light will like the “straw” type filter unit that allows you to dip one end into a water source, and suck clear sanitized water from the other. Unfortunately this requires that you have regular access to a water source of some kind, and this isn’t always guaranteed when you’re in escape and evade mode. A better alternative in that case is to utilize a filtered water bottle, or to use a filtered pump to fill an otherwise clean water bottle. Again, look to camping and outdoor stores for these. Here’s a link to just one of the many places you can find these products online: Cheaper Than Dirt Water Category.
Distillation
This is the slowest method, and really is only good if you are going to be in one place for a very long time. In general, distillation requires large amounts of energy input in order to produce clean, drinkable water. You can, however, produce solar distillation units that use heat from the sun to distill your water. If you live near the ocean this is the only method discussed so far that also is able to remove the salt and minerals from the water – making undrinkable saltwater into something fit for human consumption. Click this link to read and excellent article on understanding and building solar stills of many different kinds, including the very popular single slope still: Build it Solar, Understanding Solar Stills.
Hopefully this has given you a good start to understanding water purification and why it’s so important. In the future I’ll be sure to address actually finding water, along with some real life examples of what you can do in all sorts of situations.