Water treatment

Outdoor water filters – a must for every outdoor enthusiast!

Water treatment plays an important role on outdoor tours. Especially on longer trips, it is difficult to carry large quantities of water, as this not only increases the weight of your backpack but also the volume of your gear.

So when you’re on the move, you’re forced to think about how you can make any surface water you find safe to drink. Various outdoor water filters have proven to be particularly practical aids in the field. They take up very little space in your gear and guarantee that you always have fresh drinking water on hand.

To ensure you’re as well prepared as possible for your next outdoor adventure, we’ll give you a few useful tips on water treatment in this article. Here you’ll not only learn which tools are available for this, but also how you can build an improvised outdoor water filter with minimal effort.

 

That’s why you should always use an outdoor water filter!

Considering that about 70% of the Earth is covered with water, one might think that we must have sufficient drinking water available. However, of the total amount of water, almost 97% is salt water, while only the remaining 3% is fresh water and suitable as drinking water. On top of that, about two-thirds of all fresh water is found as permanently frozen ice at the poles. Thus, only 1% of this total volume of water is drinkable fresh water. Theoretically!

Unfortunately, most of the bodies of water we can find are polluted and cannot be drunk unfiltered. That’s why hikers and bushcrafters in particular are often forced to deal with the topic of water treatment!

Appearances are often deceptive: clear water from lakes or rivers is not necessarily safe. In most cases, tiny particles and bacteria have settled in these waters, which can cause serious health problems if you drink the water unfiltered. Since these contaminants and microorganisms are usually not visible to the naked eye, you should definitely rely on an outdoor water filter.

Standing bodies of water such as lakes or ponds in particular are a popular breeding ground for these microorganisms. But even with flowing mountain streams, you cannot be completely sure that there has been no contamination below the source. This may be caused by faeces or a carcass.

So that you can start your next outdoor adventure well prepared, we have summarized the most important contaminants that you should filter out of the water as far as possible!

The first thing we should mention here are the suspended solids present. These are usually the finest organic solids such as algae or dead plant material. These substances are not fundamentally harmful to our health, but in excessive quantities they can cause serious stomach problems.

The second major factor polluting our waters is heavy metals. This is a large group of metals that occur in nature. In water treatment, the focus is particularly on the metals cadmium, mercury and lead. Even in the smallest amounts, these are harmful to health if they enter our water cycle. This usually happens through the discharge of wastewater or through leaching of rock and soil in mining areas.

Another reason to use an outdoor water filter is chemicals. These can be, for example, industrial chemicals that can be highly toxic to us even in the smallest quantities. Such contaminants often enter our waters via wastewater. On the other hand, there are of course also chemicals used in agriculture. In this way, for example, fertilisers enter our groundwater and upset the balance of our waters.

In addition, unfortunately, various pathogenic microorganisms are also found in our waters. For example, bacteria can also be present in lakes and the like. These are not necessarily bad and in some cases help maintain our biological balance. Others, however, can be very harmful and cause infectious diseases in humans. The latter multiply particularly quickly in water, which is why you should always use an outdoor water filter. Depending on the type, bacteria reach a size of around 0.2 to 5 microns and should be filtered out as thoroughly as possible during water treatment. One micron corresponds to 0.001 millimetres.

Many bodies of water also contain protozoa that can make us very ill. These animal single-celled organisms are more highly developed than bacteria and have their own cell nucleus. Some of these protozoa protect themselves with a solid cell membrane as long as they have not yet found a host. Because this is very resistant, we need to pay a bit more attention to it when treating water. These tiny particles range in size from about 1 to 15 microns, which you should definitely take into account when choosing your outdoor water filter.

Ultimately, the water can of course also be contaminated with viruses. These are extremely small parasitic microorganisms that are not actually living beings in the strict sense. They are more like genetic information packaged in a shell. Since viruses need a host to reproduce, in the case of contaminated drinking water that host would be us. That’s why it’s so important that you choose a good outdoor water filter that removes viruses between 0.02 and 0.2 microns in size.

As you can see, there are many microorganisms that cannot be seen with the naked eye. So that you can really enjoy your next trip and, above all, stay healthy, you should take an in-depth look at the topic of water treatment. It is important that you can remove even the smallest particles from liquids with your outdoor water filter. In the next section, we’ll give you some tips to help you obtain clean drinking water.

 

What you should keep in mind before treating water!

Before you treat surface water with a commercially available outdoor water filter, you should pre-filter it. This allows you to remove suspended matter from cloudy water and separate organic solids from the water using simple means. This way your water filter won’t clog as often and you’ll enjoy your equipment for longer! There are different techniques for pre-filtering surface water. To help you get started right away, here are the two most common methods for you to try out.

For the first method, you can use a T-shirt or a towel as a pre-filter, for example. Place it over the entire opening of a collection container in which you want to collect the pre-cleaned water. You can then pour the surface water into a bottle or another container and gradually pour it over the fabric. It is important that you really wait until the water has completely seeped through your shirt. Only then can you be sure that no remnants of untreated water will enter the collection container when you remove the fabric.

Another practical method is a DIY outdoor water filter made from a PET bottle. Cut the bottle in the upper third, and use your pocket knife to poke several small holes in the cap. The separated top section of the bottle will later serve as the collection container for the pre-filtered water. Now start creating individual layers through which the contaminated surface water will have to seep. To do this, fill your bottle with one layer each of grass, sand, gravel and charcoal. Each layer should be about 3 to 4 centimeters thick. Then gradually pour the water to be purified into your homemade outdoor water filter. Now it’s time to wait: it will take a while until the pre-filtered water collects in the container.

At this point we would also like to point out that both methods are only pre-filtering. The water in the collection container is only freed from coarse impurities, not from microorganisms. Therefore, after using these two methods, you should definitely resort to an outdoor water filter. We’ll tell you which options have proven themselves in the next section!

 

Outdoor water filters – options for reliable water treatment

Beforehand, you should be aware that bacteria and protozoa are the most widespread microorganisms in surface water. You should always assume they are present in any body of water! Viruses, on the other hand, are usually only found near human settlements, where wastewater or feces have come into contact with surface water.

There are countless ways to treat your water and make it drinkable. To ensure you’re ready to go next time, we’ll show you the best-known treatment methods here.

Boiling water

To begin, we want to start with the most common and simplest method: boiling! This is a basic survival technique that people have been using for many centuries.

The big advantage of boiling is that most disease-causing microorganisms die at temperatures of 60–70° C and are thus removed from the water. Of course, there are exceptions and some viruses that are somewhat more resistant. That’s why you should definitely wait until the water is boiling and let it boil vigorously for three to five minutes!

 

Practical tip: If you are out in high alpine terrain, the boiling time of water increases! Roughly speaking, you can assume about one additional minute for every 300 meters of elevation.

In addition, boiled water does not remain germ-free permanently! If it stands for a longer period, microorganisms can accumulate in it again and contaminate the water. Therefore, you should drink boiled surface water within a maximum of 24 hours or treat it again!

One disadvantage of boiling is the extensive equipment you need. From the stove to the pot to the fuel, you have to have everything ready in your kit. In addition, heavy metals, chemicals and suspended solids cannot be removed from the water by boiling!

Now we come to the classic outdoor water filter, which you can use to treat surface water on the go. Good versions have very fine filter elements and a micron rating of 0.2. They can optimally filter suspended particles out of the water. In addition, they separate a large proportion of bacteria and protozoa from the surface water.

Because viruses are usually much smaller, classic outdoor water filters often reach their limits here. For this reason, we recommend using two methods in this case. First, you should treat the surface water with a 0.2-micron filter and then boil it for several minutes to kill viruses.

 

Pump or flow-through filters

This is a particularly popular outdoor water filter. Because it is especially light and compact, it fits into any kit. To treat water with this type, you simply pump the surface water to be purified through a hose into the filter. You can then collect the purified water in a container via the second hose. A major advantage of these outdoor water filters is the activated carbon filter. This is integrated into many filter variants and neutralises the taste of the water. In addition, the activated carbon can reliably remove organic substances from the water so that you have clean drinking water available after treatment.

 

Chemical aids for water treatment

With these agents it is possible to kill all disease-causing microorganisms in the water, including viruses. However, chemical water purifiers cannot remove heavy metals or chemicals. In addition, suspended solids remain in the water when these aids are used. Pre-filtering surface water is therefore extremely important when using these outdoor water purifiers! This is particularly crucial when using chemical agents for treatment, because suspended solids massively reduce the effectiveness of Micropur tablets or similar products. For this reason, the water must be as clear as possible when using chemical outdoor water purifiers!

It’s also important to know that chemical outdoor water filters require a longer contact time to reliably purify surface water. Here, you should allow between 30 minutes and 2 hours. This is because bacteria and viruses are killed after about 30 minutes, whereas protozoa protect themselves with a very resistant cell membrane and therefore require a much longer exposure time.

One major advantage of chemical outdoor water filters is how long they remain effective in the water. As the only filtration method, they keep treated water germ-free for up to six months. Other outdoor water filters, by contrast, lose their effectiveness after just a few hours, meaning you are then forced to treat the remaining water again. And that’s not all in terms of benefits! When it comes to longevity, chemical filtration methods also impress with their long service life. In addition, thanks to their small pack size, they can be stored in any bag.

However, there is of course one small drawback we don’t want to keep from you. With chemical water treatment, the chlorine it contains often makes itself noticeable in smell and taste. If that bothers you, you can use anti-chlorine tablets to remove the smell and taste within a few minutes.

 

Water treatment using UV light

Did you know that you can free surface water from microorganisms by treating it with UV light? Our top brand SteriPEN is the market leader in this segment and produces high-quality UV outdoor water filters. The DNA of bacteria, protozoa and viruses is destroyed by short-wave ultraviolet light. This prevents these types of microorganisms from reproducing and thus renders them harmless. A major advantage of this method is its easy and fast application. You can assume about one minute of exposure time per litre of water. To ensure that the effect of the UV rays is not impaired, it is also important here to pre-filter the water and remove suspended matter. As with the aforementioned methods of water treatment, these water filters unfortunately are also not able to remove heavy metals or chemicals from the water.

 

Where you should look for water

When you’re out in nature, there are a few things you should pay attention to in order to find a water source quickly. The most obvious are, of course, your own senses. While you’re scanning the area for water, you should also listen carefully to see whether you can hear the sound of a stream nearby.

You also have the option of collecting rainwater. You can easily do this with a plastic bag or a bucket. However, this method will take quite a bit of time, which is why we want to present you with some other ways of finding water here.

For example, you should pay attention to animals and their tracks. Some stay permanently near water sources and therefore usually lead you exactly where you want to go. The dragonfly, for instance, is an animal that can definitely be associated with water. They generally move no more than 300–400 meters away from their water sources and are therefore an important indicator when searching for drinking water. Wild bees also tend to stay near larger bodies of water and can help you find them. In addition, there is a bird that is definitely associated with a pond or similar body of water: the heron. Herons feed mainly on frogs or fish and are an indication that there is a water source in the immediate vicinity.

In addition, you should look out for certain plants that require a great deal of moisture themselves and are therefore often found near streams and the like. These include, for example, willows or reeds. Horsetails are also usually found in wetlands, which is why they too can be an indicator of a water source.

 

You should avoid these water sources!

As a rule, you should avoid water from puddles and standing bodies of water. These are often heavily contaminated and, warmed by the sun, can become breeding grounds for bacteria or protozoa. Fallen leaves also cause the water to become more acidic, which can lead to health problems.

Another taboo is surface water from larger rivers! The water there is usually contaminated with heavy metals. In addition, you will find residues of fuels or chemicals in these waters, introduced into the rivers by shipping and industry. To prevent serious health problems, you should absolutely avoid water from these sources!

As an indication of the actual water quality, you should also look out for so-called bioindicators. They are also referred to as indicator organisms and provide information about the quality of a body of water. For example, non-biting midge larvae or river lampreys can be an indication that the water is of good quality. If, on the other hand, you discover a rat-tailed maggot or the red sludge worm under stones in the water, you should definitely keep your hands off it! Both indicate poor water quality, meaning you should not treat this surface water for drinking!

 

Questions: Water treatment

What are the advantages of an activated carbon filter?

Some typical outdoor water filters are equipped with an activated carbon filter. This can absorb organic compounds and thus improve the taste and smell of stale water. In addition, activated carbon can bind some bacteria and filter certain agricultural chemicals out of the water, as long as they are organic fertilizers.

 

Can heavy metals be removed from water?

Heavy metals are very difficult to separate from surface water using an outdoor water filter. The only truly helpful method would be distillation. However, this is hardly feasible in nature without special equipment. For this reason, we strongly advise you to avoid bodies of water near industrial areas. In addition, waters in mining regions are often heavily contaminated with heavy metals, which is why you should definitely avoid these areas when searching for water!

 

How can I treat water if I don’t have an outdoor water filter in my pack?

If you don’t carry a purchased outdoor water filter with you on your tours, there are numerous ways to build one yourself on the go. To filter suspended particles from the water, for example, you can use a towel or a T-shirt. With this method, you place the fabric over a large collection container and slowly pour the surface water to be purified over the fabric. Since the water in the collection container is now only freed from suspended particles, you should definitely boil it. Other contaminants unfortunately cannot be removed with this method.

Another very well-established survival technique is a self-built layered filter system. For this you can use an empty PET bottle and rely entirely on natural materials. First, you should cut your bottle in the lower third with a pocket knife. You use the larger piece for your filter, while the remaining piece serves as a drinking cup and collection container. Make several small holes in the cap with your pocket knife so that the treated water can drip through later. Now you should create individual layers about 3 to 4 centimetres thick from gravel, charcoal, sand and grass, through which the water can slowly seep. Please note, however, that this is purely a survival technique. Whenever you can, you should boil the pre-filtered water and treat it with an outdoor water filter.

 

Which surface water is suitable for treatment with an outdoor water filter?

To prevent health problems, you should always look out for smaller, flowing bodies of water whenever possible. A stream will very likely offer good conditions for obtaining clean drinking water after treatment. Whenever possible, you should go to the source of a stream. Only then can you be truly sure that the water is harmless. As a rule, however, you should first take a close look at the surroundings. In particular, you need to determine whether there might be an animal carcass or waste nearby that could contaminate the water. If you don’t find anything of the sort in the immediate vicinity, you can draw water from this spot for treatment.