Getting water from a river in the mountains, or drinking directly from a tap abroad, are both clearly inadvisable practices. Water from these sources can contain bacteria and other harmful organisms that can cause illness. However, it is imperative to have access to drinking water for hydration, cooking and hygiene (including tooth brushing). This is crucial to our survival.
When hiking or traveling, obtaining drinking water is not always easy. Fortunately, there are portable filtration systems that offer a solution to this problem. Brands such as Katadyn, MSR, LifeStraw, among others, offer different types of water filters in their range. For novices and experienced adventurers alike, the choice can be complicated.
In this buying guide, we'll highlight the fact that there is no single, universal solution, but rather an answer adapted to each specific need. Indeed, needs differ depending on whether you're a backpacker or someone going on a road-trip in a van, for example. At the end of this presentation, you'll have all the information you need to select the optimum water filter for your type of activity.
Why choose a water purifier?
During dynamic outdoor activities such as hiking or mountaineering, it's advisable to consume at least one ortwo sips of water every 10 minutes to avoid dehydration. Over the course of a day, this quantity can quickly become significant. The purpose of the water filter is to reduce the weight of your rucksack by allowing you to refill your water bottle as you go, as soon as you find a water source.
This involves careful planning of your itinerary and pre-locating the water points you'll come across. These may be streams, rivers, springs, fountains or even puddles. Indeed, some water filters are capable of purifying turbid water, provided it's not stagnant. The freshness of the puddle is important. All in all, the water filter brings you valuable convenience. Relatively compact and lightweight (depending on the model chosen), it frees you from the constraint of how much water to carry during your outdoor activities.
For more stationary activities such as bivouacs, base camps or humanitarian missions, the principle remains similar. Providing enough water for several days or several people can quickly become a headache. Owning a water filter improves your quality of life. The issue of water ceases to be a major concern, as you simply refill your supply at the nearest water point.
As you will have gathered, each type of filter is designed to meet a specific need. Although they all share the same purpose, i.e. to make water drinkable, their ergonomic design differs. Each model has its own advantages and disadvantages.
The different technologies
Often misunderstood (or poorly explained), water filter technology is actually quite simple to decipher. Each filter is equipped with a specific technology, i.e. an element that acts as a filter to purify the water. Here are the different technologies found in water filters:
Membrane: This part of the filter has micro-perforations that allow water to pass through under pressure. Some fiber membranes, like the Sawyer filter, are self-cleaning and extremely long-lasting. Depending on the model, this filtration can eliminate the vast majority of impurities (up to 99.999%).
Glass fibers: With the exception of viruses, this system can capture most impurities, including chemicals. Pumping is smoother with this technology, but these filters cannot be cleaned. Their service life is generally shorter than that of membrane filters. The Katadyn brand uses this technology.
Hollow fibers: Virtually equivalent to glass fibers, hollow fibers do not retain chemicals or alter the taste of water. Nevertheless, they are compact and lightweight. Ideal for those looking for an ultra-light filter.
Activated carbon: This fairly basic technology is only effective for filtering chemicals and improving the taste of water. An activated carbon filter is not suitable for removing protozoa, bacteria and viruses.
Ceramic: Although not effective against viruses, the ceramic filter is one of the most efficient on the market. It is suitable for all types of water, including very turbid water. What's more, it's easy to clean. Its only drawback is its fragility: if dropped, the ceramic cartridge can break, rendering the filter unusable.
In addition to these technologies, there are also UV treatment systems, ion exchange treatments and, of course, chemical treatments (which are virtually the only ones on the market to be effective against viruses).
The technologies described above are designed to filter pathogens of different sizes. The higher the filter performance, the smaller the size of the agents filtered in microns (µm). Here are a few examples of well-known filters on the market:
The Sawyer Mini uses fiber technology with filtration at 0.1 µm. It is one of the most efficient filters, equipped with a membrane filter.
The MSR Guardian can stop viruses thanks to its 0.02 µm filtration. The Guardian is one of the most complete filters available.
LifeStraw filter straws and Katadyn filters (using hollow fibers) have a performance of around 0.2 µm. This is also the case for MSR TrailShot.
The Aquamira Frontier Pro offers 2 µm filtration and is less efficient.
As a guide, here are the sizes of the pathogens:
1 µm to 15 µm: amoebic dysentery, giardia, lamblias, cryptosporidium, etc.
0.2 µm to 5 µm: E-coli, salmonella, cholera, etc.
0.02 µm to 0.2 µm: hepatitis A, Norwalk virus, rotavirus, poliovirus, etc.
Depending on your activity, micron performance may be more or less important. For example, if you're hiking in Europe or North America, filters around 0.2 µm are generally sufficient. On the other hand, for a trip to a developing country, it's best to opt for a water filter offering high-micron filtration to minimize any risk of contamination.
As a general rule, portable filtration systems have an average flow rate of between 1 and 2.5 liters per minute. This means it doesn't take long to fill a water bottle. This is particularly sought-after when hiking or running self-sufficiency races, as it saves time and increases efficiency.
Filters designed for more stationary activities, such as bushcraft or bivouac, generally have a lower flow rate. This is particularly true of gravity filters. However, they offer other advantages. Most of them require no effort, as the water flows naturally. When choosing your water filter, be sure to take this criterion into account, and opt for a flow rate that matches your activity: a high flow rate if you're in a hurry, or a lower flow rate if you're not under time pressure.
The autonomy of water filters can vary considerably. Some models can treat up to 100 liters of water, while the most autonomous can filter several hundred thousand liters. For less autonomous filters, it's important to note that most of them allow you to buy replacement cartridges, which means that the filter itself doesn't need to be thrown away.
In any case, regular maintenance of the water filter is essential. Indeed, filter autonomy can be considerably reduced by the build-up of bacteria, protozoa and other pathogens that foul the filter element.
What's more, some products are not suitable for use in muddy or turbid water. Ignoring the manufacturer's recommendations can lead to clogging of the filter and render it ineffective. Although autonomy is an important criterion when choosing a filter, it is crucial to respect the conditions of use and maintenance to obtain the indicated values.
For example, some people are frequently surprised to find that their TrailShot filter no longer works properly, even with a 2,000-liter autonomy. If the filter is used in muddy water without being cleaned, the hollow fibers can crystallize and cause a blockage.
Weight and dimensions
Finally, weight and dimensions must be taken into consideration for any activity on the move, be it bushcraft, hiking or van travel. Just like a tent or a stove, the compactness and lightness of your water filter are essential criteria for increased comfort. This makes it easy to transport and store.
However, it's important to note that some ultralight filters are not suitable for groups or for high water demand. So, the most appropriate choice will depend on your individual situation and needs.
The different types of filtration
The filter straw is a tube-shaped device that you suck through to drink. The water passes through the filter and becomes drinkable. The advantage of this filtration system lies mainly in its weight and dimensions. The filter straw is both lightweight and compact, making it an ideal choice for ultralight hikers (MUL).
What's more, depending on the model, some straws can be attached to a flask, water pouch or bottle. The Sawyer Mini filter, for example, offers this versatility. As a result, you have several options:
Drink directly from the water source.
Fill your water bottle and drink through the straw in it.
Attach to a water bottle or pouch and transfer to a water bottle.
Attach to a water pouch.
However, it's important to note a few drawbacks associated with this type of microfilter filter. They don't work effectively, if at all, in turbid water. Otherwise, you risk clogging the filter, rendering it ineffective. What's more, filter straws are not designed to treat large quantities of water. This is not due to their autonomy, which is generally several thousand liters, but rather to the fact that they require a suction effort that can be demanding, especially at high altitudes.
Finally, filter straws are designed for personal use and are not recommended for group use, mainly for reasons of hygiene.
The filtering gourd
Very similar to filter straws, the filtering gourd works in the same way. All you have to do is suck it up to obtain filtered water. Its main advantage lies in the comfort it provides. All you have to do is gradually fill your gourd at water sources (streams, fountains, etc.) and drink as you would from a conventional bottle. No need to unscrew, decant, etc.
The best-known model is probably the LifeStraw Go filter bottle. Equipped with an activated carbon cartridge in addition to the hollow-fiber filter, it is effective against bacteria, protozoa and chemicals. What's more, it reduces bad tastes, something that filter straws don't do (where the use of a Micropur tablet may be necessary, which we'll get to later).
As for the model most commonly used for hiking, this is the Katadyn BeFree. Unlike the LifeStraw Go, the BeFree does not feature an activated carbon capsule. However, its flexible water bottle saves space in the backpack.
The disadvantages of filtering water bottles are similar to those of filtering straws. It is not recommended to filter cloudy water with these systems, as most gourds have a hollow-fiber or membrane filtration system. What's more, a filtering gourd can be bulkier and heavier than a filtering straw, as is the case with the LifeStraw Go. That's why some people prefer to opt for a straw and filter the water directly into their unbreakable Nalgene bottle.
The pump filter
As the name suggests, using a pump filter involves pumping to filter the water. This means that the suction action is set aside in favor of a more manual effort. As you will have gathered, this type of filter is particularly suited to groups in the first instance. The filtration process involves immersing the hose in non-potable water, then pumping over a container (flask, water bag, jerrycan, etc.). With a flow rate of around one liter per minute for the less sophisticated models, this can requireconsiderable effort depending on the quantity of water required.
However, the main advantage of the pump filter lies in its ability to purify turbid water. It is capable of eliminating all types of contaminants: bacteria, protozoa and even certain viruses, depending on the model. One example is the Guardian made by MSR. Unlike most pumps with ceramic filters, the Guardian uses hollow fibers. The increased volume of these fibers enables it to be effective against microorganisms as small as 0.02 microns (compared with 0.2 microns in other hollow-fiber filters), the size of a virus. In short, this makes itone of the most effective models on the market. This makes pump filters particularly suitable for expeditions to areas where access to water is difficult, where the water is cloudy and muddy, and for groups.
Gravity filtration meets an entirely different need: to obtain large quantities of drinking water. Gravity filters operate without pumping or suction. They require no effort at all. All you have to do is fill the tank, then turn on the tap and the drinking water flows out. This is a particularly practical option when camping, at a base camp or on a bivouac. It's also very popular with groups.
Disadvantages vary from model to model. Gravity water filters such as the LifeStraw Mission and MSR Guardian Gravity filter out viruses (thanks to hollow fibers with 0.02 micron pores), but have a very low flow rate (between 20 and 50 cl per minute). The BeFree Gravity has a better flow rate of 2 liters per minute, but does not filter out viruses. There are also gravity water filters designed for more stationary use. This is particularly the case for vanlife enthusiasts, motorhome owners or even forest huts.
In short, gravity filtration is generally slower and can be more complex to install, but it requires no effort on the part of the user.
Last but not least, there are chemical water filters. Forget all the features mentioned above: flow rate, technology... These filters work in a rather special way. Available in liquid, powder or tablet form, you simply add them to your water to disinfect it and make it drinkable.
Although they are not effective in cloudy water, they are very effective in clear water. Chemical treatments such as Micropur, which contain chlorine and silver, eliminate viruses, bacteria and protozoa. Micropur is particularly useful as a supplement to a filter, when you have doubts about the quality of a water source, or to preserve your water. If you have a 10-liter can of water, a single tablet of Micropur Classic can preserve it for 6 months.
Extremely lightweight and space-saving, the adoption of this chemical filtration system eliminates any risk when drinking suspect water. That's why it's used in so many fields, including boating, bushcraft, hiking, travel and more.