Survival Water Filtration Systems: Water Purifying Methods You Should Know

Lifestraw filter
Samuel Funt
Written by Samuel Funt

Water is our most important means of survival on this planet. Our body cannot function with 5% or more dehydration. Upon 2-3% or dehydration you feel extremely thirsty and that’s usually when most people take measures. Our body needs to replenish its liquid since thanks to it our body detoxifies through the release of urine and sweat. If you’re so dehydrated that the body cannot release enough sweat or urine to remove the toxins, the cells in your body will stop functioning properly until they get permanently damaged and you will basically die.

That doesn’t mean though that you can drink any water that you find. Unclean water can be as damaging and fatal as no water at all. You shouldn’t underestimate the dangers of the many organisms that thrive in water and snow. Yes, even snow that has been there for some time has probably already been contaminated.

How to find Water

There are both basic methods to filtrate the water, and also purification systems that are popular on the web.

Water purification systems for survival situations

We’ll give you some handy tips and tricks on how to purify water in survival situations. Some are useful because they don’t require extra tools or gear in order to filtrate the water. Others are practical nonetheless and may require that you buy some additional machines or systems to achieve the same effect. The final choice is up to you. Some systems may be far more reliable than some primitive methods. So, as life is invaluable, a system slightly more expensive would be worth it.

Gathering water

The first and most basic way for purifying water is the plain old boiling method. As is obvious, you need a heating source (fire) and a metal container. How long you should boil the water is questionable, since time varies from 1 minute to 10 minutes. Of course, it makes sense to keep it boiling longer than a minute. In fact, the longer you boil it, the more you’ll be sure that the bacteria and organisms are dead.

A very important point we have to make is that if you’re in a mountainous area and you’re high above sea level you’ll have to remember that water boils slower in high altitude areas due to the low atmospheric pressure. So, the higher you are, the longer the water should boil. A noteworthy thing though – the higher you go in elevation, the lower the risk of water contamination, since contaminants are usually spread via animals. And as we know animals live mostly below the tree line. So you may want to keep that in mind.

You can learn more about this method from our article on how to purify water.

Another method, not so primitive, is adding chemicals. There are specific types of chemicals (not all will do the trick, most would poison you) for water filtration. Some of the most used chemical treatments are bleach, iodine, hydrogen peroxide, potassium permanganate and sodium chlorite. These may already sound scary but don’t worry. These chemicals are usually sold as tablets for hikers and mountaineers, so it’s not something new and untested.

There are of course details you need to know and follow strictly. So, when you add the appropriate amount of tablets into your water bottle or container, wait for the chemical to work and don’t drink the water within the next 30 minutes. You need to be patient with this water treatment and wait for the chemical to kill the organisms. You can use bleach also (one with no additives, scents, designed to protect colors, etc, nothing fancy).

It’s a strong chemical though and if you don’t know what you’re doing we highly advise you not to use this method. Use only tablets which are specifically sold for hikers in survivalists’ or hikers’ shops. As for iodine, use a 2% tincture and drop about 5-10 droplets for a liter of water. Again, wait for 30 minutes and then you can drink the water. Also, iodine is not a good method for long-term treatment. If you prefer it, try to vary by using other chemical tablets.

You can find reviews for best products and more information on how to use such products, in our article on water purification tablets, so make sure you check it out.

And of course, we have to talk about those commercial filtering systems that are out there. Many of them use pump systems, where you place one hose in the water, and another in your bottle (water container) and pump so that the second hose basically pumps out the purified water. Some such systems may be slightly heavier than you’d want to carry, others may be smaller but probably more expensive. There are others like Katadyn mini, which is a very small and light filtering system with a ceramic filter. It weighs 10 ounces and is small (as the name suggests).

Be careful with ceramic filters though. If you drop them by accident, they break very easily. The same thing is with extreme cold. If the water inside freezes it expands and can shatter the filter. Otherwise, these systems last for years and if you find a compact light-weighted version, by all means, enjoy it. It’s much better than drinking chemically purified water (which has different and unpleasant taste).

Be aware though that some filtering systems may not be able to filter viruses or microorganisms, so before you commit yourself to a purchase, read the manufacturer’s labels and claims. Don’t just assume that all filtration systems are the same in quality and technology.

We have a great article, with reviews and important features for straw filters (the most recommended for hikers and outdoor enthusiasts). If you are interested, you can read all about it here.

In some cases, you may not be prepared with any of the above. That happens even to professionals. That doesn’t mean of course that it’s ok to do it often, but if you by mistake forgot your purifying system, here are two ideas for you.

Use soil or sand as the filter. They have the unique property to filter viruses, bacteria, microorganisms, etc. So, in order for this to work its miracle, get a container (your bottle or a cooking gear) and a shirt. Place the shirt on top of the container opening and then put sand or soil above the opening. Start pouring water through this ‘filter’. If the water that comes out is unclean and muddy, remove it, and wait until it actually runs clean. Then you can collect and drink it.

Purifying water

An alternative method is to just dig a hole where water will accumulate and drink it. But you have to be aware that this method may not be completely reliable, since some organisms may still have found their way into the ‘filtered’ water. Better off use the first method.

Another trick for you is to use the so-called solar distilling. It works like this. Dig a hole and pour water there (or wait for it to accumulate). Place the container or bottle in the middle of the hole (that’s where the clean water will collect). Then take a large enough plastic cover and place it over the hole, so it covers it entirely. You can place heavy objects like rocks on the edges of the plastic cover. Make sure that this plastic sheet doesn’t touch the container or bottle’s opening. You’ll see why.

So, if you’re all set finally you can place a rock right on top of the plastic sheet, so it points exactly above the container’s or bottle’s opening. Basically, the greenhouse effect will force the water to condense on the rock placed above the plastic sheet and will drip right into the container. It may be the slowest and most tedious process of all the above, but if you ran out of any ideas or are in a serious need of water, this can be a good reliable method. It’s an old one so you can be sure others tried it too and came out alive.

Solar distilling

A nice tip to round up this method is that you can place some leaves or vegetation inside the pit (along with the water), so you can increase the water content. As you know vegetation contains water so while in heated areas they just dry up; they lose the water stored in the plant’s cells. That’s how you can end up with a bit more water in the container or bottle than initially.

If you are interested in methods to get distilled water, we have an in-depth tutorial that will help you out, so take a look at our article on how to make distilled water.

What to consider when buying a filtration system?

There may be some aspects to be considered before you commit yourself to a purification system.

You have to know that filtering and purifying the water has slight differences in the technique and effect. The filtering system is capable of filtering bacteria and protozoa just fine, but doesn’t kill viruses. That’s why people are usually advised to carry both a filter and chemicals (for killing what’s left alive).

Whereas purifiers are definitely the stronger option since they kill all living organism and viruses, but they also involve chemicals in their system. Here is a quick tip, UV light kills bacteria and viruses just as fine. For example, the above-mentioned Katadyn system is a filter, while Aquamira water treatment is a purifier.

Katadyn system

So, filtering systems are doing a pretty good job at filtering living organisms, except for viruses (which are not living organisms). Filters leave the water tasty as well. Which is a bonus.

When it comes to the chemicals we talked about before, they definitely improve the quality of the water, killing all organisms, including Cryptosporidium. The only downside to using chemical treatment is the deterioration in the water taste properties.

We should also talk about the UV purifiers. They kill everything, except for pathogens. The only thing that deactivates them is that the UV light damages their DNA and they can’t replicate. Thus, they are of no danger to your health. You still need to be careful since if the purified water stays exposed to light for a long time, these pathogens may reactive again, and you’ll need to use the purifier again. So UV purifiers are a really good option.

Aquamira Chlorine Dioxide Water Purification Treatment Drops

Hikers may even carry their own UV system and devices, although the EPA hasn’t approved of this yet. Otherwise, UV purification systems are widely used in commercial filtering and purifying systems.

So here is our tip. You can carry both a filter and a purifier since both systems have their pros and cons and working together you’ll be completely safe, but is it necessary to burden yourself with too much weight? Know the area you’re heading to. If it’s a completely deserted area, where animals don’t live, you’ll be relatively safe and a filter would be enough. If you go in forest areas, jungles, and the likes, you should definitely take the purifying system (viruses thrive in such areas).

Hiking anywhere in USA, Canada (North America) would require only a filtering system. If you plan an international trip to places you are not acquainted with you should definitely prepare the purifier (or chemical system). There are different climate conditions, different environments, etc. and you have no idea what viruses are active there. You have to fight them effectively. Good purifiers are First Need XL or SteriPEN. You can also use a chemical treatment for better effects.

First need water purifier

Consider also the weight of the filter or purifier. The weight varies dramatically. Some heavy filtering systems may also be much more effective than others and be worth the additional weight. For international trips and weeks of time spend away from home you will definitely need a more reliable system.

If you go hiking for just a few days, a filter and/or a chemical treatment may be just enough. Take into consideration also how much time you’re willing to wait for the water to be ready for drinking. Some systems may act really quickly, others surprisingly slow. Read the manufacturer’s label and claims and decide for yourself. Most systems and chemical treatments shouldn’t take more than 30 minutes, but again, the numbers vary.

You should also know how many people are going on a hike with you. Is it just you alone, or you and your family, or you’re going with a group of friends? Some systems work fine for a sole hiker. Like the Katadyn Mini. It’s small and ideal for one person. But it would be tedious and time-consuming to use it for a group of people. Gravity-fed systems though are ideal for more than 2-3 individuals since they can treat large amounts of water for a short period of time.

Katadyn Mini Ceramic Filter

Also, when you decide to go for a filter you may often come upon a term – micron size. This basically indicates the size of the filter’s pores. The smaller the size, the more particles, organisms and particulates it will strain out. A good way of measurement is to know that the smallest living bacteria are usually 0.2 microns. Based on that, you need a filter micron size of 0.2 or smaller.

Another interesting thing to talk about is the durability of the system. This means, how often it needs scraping the clog, and its longevity. Ceramic filters can process about 2000 liters until they run out of life and need to be replaced. Other filters may live less and give up at the 500th liter.

When it comes to replacement, you can find cartridges on the web pretty easily. UV purifying systems work on a completely different principle – they use batteries and bulbs. When it comes to UV lamps they can hold really long. Most can last for up to 8000 treatments. Consider the batteries though. They run out of power at the 40-100th treatment.

Of course, our tips would be incomplete if we don’t talk about experience. Most hikers consider filtering systems to be too heavy and they get discouraged at packing them for their trips. It is true that there are newer lighter versions of filtering systems, whose weight is insignificant. Usually among hikers and survivalists the Aquamira water treatment drops seem to be the most preferred option, due to its low weight and quick purifying ability.

We hope we gave you some valuable tips and knowledge about the filtering and purifying systems out there. All the options on the market are worth the try and nothing is more precious than your own experience. You are welcome to try all the above-mentioned methods and systems to gain your own experience and test the knowledge we presented to you.

You can try borrowing filtering systems from friends and test them in safe conditions. The more options you try, the better you’ll be equipped with practical skills. If your close friends have UV purifiers you should definitely ask them to show you how to use them. Ask your friends to share their own experience and what they learned by using these systems.

You could also test all the methods presented here with water from the same source. See how each system cleanses it, changes the water’s taste and properties. It’s invaluable to put theory into practice. Of course, you can’t try and test all methods out there, but whichever you have access to, via friends and relatives, we strongly advise that you practice before you go hiking.

Samuel Funt
Samuel Funt

Samuel is a prepper with over 15 years of experience. Samuel is excited to share his knowledge and the things he learns while travelling in British Columbia, Canada where he lives and around the world.

  • Ben Lewis

    The fundamental concern is that without a steady, clean water supply, you won’t last much past 3 or 4 days, even in the best circumstances.

    Staying well-hydrated should be your primary concern out there.

    • Samuel Funt

      A 72-hour survival kit is a contingency, but you should strive to get help as soon as possible.

  • Sawyer Mini is my favorite water filtration system. It is cheap, highly effective and durable.

  • Hi Nidal,

    Sawyer has come out with many water filtration products and all of them are highly recommended. They understand what hikers need and know how to deliver them.


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