Essential to life of any kind, water is something none of us can go for long without. If you’re venturing off the beaten track on a backpacking trip far from any modern infrastructure, you’ll need to choose a water filter before departing.

Water may look pristine, but you never can tell. Whether contaminated by livestock, wildlife or chemical pollutants upstream, you simply need to choose a water filter that’ll filter out those harmful pathogens. By not doing so, you run the risk of getting violently sick. And of course getting sick on the trails far from help is something best avoided.

How to choose a water filter

There are two principal types to choose from, namely filters and purifiers.

Filters work by straining out protozoan cysts and bacteria. Such biological pathogens exist in the water in most developed countries and exposure to them may result in serious gastral discomfort.

Purifiers, in addition to neutralising the above, also nullify viruses. Purifiers are essential if you’re travelling to less-developed countries where exposure to viruses such as hepatitis A and norovirus may be a risk.

There are several types of filters and purifiers available on the market. From ultraportable, lightweight solutions for individuals to large capacity solutions for all the family.

Types of water filters and purifiers

Gravity Filters and Purifiers

As the name suggests, this type of filter relies on gravity. You simply fill up a reservoir with water and hang it from somewhere solid — a tree branch usually works well. Comprised of an inline filter, the falling water is forced to pass through while the offending microorganisms are prevented from passing through into the collection area.

Gravity filters excel for large groups of people and require no manual labour during the filtration process. The 2 main disadvantages are that it does require some time to collect a substantial amount of potable water, and obtaining water from a shallow source is difficult.

UV Light Purifiers

Extremely common on the backpacking trails in less-developed countries, UV light purifiers are a quick and easy clean water solution. To use them, you simply fill the bottle and insert the prong before pressing a bottom to activate the UV light. One minute later you’ll have successfully treated your water.

While they provide a simple solution with little to no maintenance necessary, they do have the drawbacks of requiring batteries and only catering for small quantities — usually a litre at a time.

Pump Filters and Purifiers

A purely mechanical solution, you simply drop the attached hose into a water source and pump the water through an element into the reservoir. A great on the go solution, they allow you to purify small quantities of water quickly and easily from the shallowest of sources. Pump filters do however require manual effort and cleaning of the element is required in the field.

Straw Filters

The ultimate solution for those explorers who require an ultralight portable solution. With a built-in element, you simply dip the straw filter into a water source and use it like it were a straw. Very affordable and much more portable than other filtration systems, they provide easy access to clean water with minimal effort required.

However, with that convenience comes the drawbacks. There’s no way of storing water, so it can only be used when you have a water source available. In addition, regular cleaning of the element is required, and it’s generally only a solution for one person.

Squeeze Filters

With this type of filter, you simply fill the reservoir — generally about a litre in capacity — and then as the name suggests, squeeze it through a filter element as your drink. The squeeze filter provides a lightweight, quick and easy solution to water filtration with an element that’s easily replaceable. The limited downsides of this method include the small capacity of the reservoir and the infield cleaning of the filter that’s required for continued use.

Chemical purifying solutions

For those who would rather not carry any hardware, several chemical-based solutions can be used to kill off harmful pathogens in water. Iodine and chlorine are the most commonly used. They come available in pills or drops and can be added to a water bottle.

Inexpensive and easy to use, they can be easily packed in a backpack as your primary source of water treatment or simply as a backup to your main filter. One drawback of this solution is the chemical-like taste of the water, although this can be negated with taste-neutraliser tablets. Another disadvantage is the time required for the chemical treatment to complete. Depending on how much water you wish to treat, it may take anything up to 4 hours before you can drink it.

If all else fails - boil it

With a stove and a saucepan, you can effectively treat water by bringing it to the boil for one minute. With the only cost being that of fuel, it provides a reliable way to treat water. Just remember that if you’re at altitude, you’ll have to boil it for a little longer due to the lower atmospheric pressure.

The downside to boiling is the time required to heat the water and then the additional time required to allow it to cool. You may want to bring extra fuel for the stove if this is your primary method of water purification.