Which system to choose to purify water on a hike?

If you want to know why it is essential to purify the water while hiking when you do not know its quality, or if you wonder if you need a purification system for your hikes:

So I advise you to first read the article “Stream, I will not drink your water” unless it is purified.

In this new article, I’ll present an overview of the advantages and disadvantages of the main purification processes. This article will help you choose the purification system that best fits your practice – if you need one. Or to realize that the one you are using is not suitable.

If you think that putting a Micropur tablet in a water bottle allows you to drink any water, you are mistaken.

If you think that filtering polluted water with the latest fashionable filter will keep you from getting sick, you’re wrong too.

Like when you buy an antivirus for your computer, when you buy a water purifier, it’s easy to feel protected for all contaminants – especially when it’s expensive. The reality is very different …

How to prepare your stream water?

Whether you purify your water or not, it must be collected and prepared properly to limit the risks. Here are some tips for doing this:

  • Take the clearest water possible and as far upstream as possible from human activities.
  • Take the water as far as possible from all polluting activities.
  • Avoid stagnant water, microorganisms grow more easily.
  • If the water is cloudy or contains particles it is best to pre-filter or decant to get rid of these particles.

Why and how to get clear water?

If you intend to purify water, it is essential that it is clear if you use a filter, a chemical purifier or a UV treatment. This will avoid clogging your filter or reducing the effectiveness of UV or chemical treatment. If you do not intend to purify the water, it is not essential, but it will just avoid the taste of mud and the sand that crunches under the tooth.

The settlement involves placing water in a container and let stand. This allows particles in the water to fall to the bottom of the container. The smaller and lighter the particles, the longer this process takes.

If the particles are very small or very light, it is better to pre-filter the water. You can do this by passing the water through a coffee filter, a cloth, a T-shirt, or whatever.

Once your water is clear and ready to be purified, shake the container to oxygenate the water and get rid of some of the anaerobic organisms.


The principle of this method is simple. Just boil water for a while to kill pathogenic organisms. This is probably the first thing most people think about getting rid of contaminants in the water. The problem with this method is that it has a lot of disadvantages and few benefits for hikers.

Advantages :

  • Convenient for cooking.
  • Eliminates most bacteria, viruses and micro-organisms.
  • No additional equipment needed (if you already have a stove) apart from the fuel.


  • Uses additional fuel.
  • Long process – even longer at altitude.
  • Purified water is hot. This is not ideal if you want to drink it and cool off.
  • Bad taste – after boiling.
  • Do not eliminate particles.
  • Does not eliminate chemical pollutants.

How long does it take to boil the water?

The required boiling time is difficult to determine because it depends on the type of pathogenic organisms present in the water as well as the altitude at which you are.

At sea level, water boils at 212 °F . The majority of biological contaminants are killed in less than a minute at this temperature. For the same result, the boiling lasts a few minutes when the water is at 185 °F (boiling temperature of the water at 2.7 mile altitude) and about 30 minutes when the water is 158 °F (boiling point of water at the summit of Everest).


See this on: Amazon.com

The principle of a filter is simple: water passes through small pores that trap organisms and particles – just like a colander to drain pasta.

There are many different types of filters. Some are membrane, others cartridge, some fiberglass, some ceramic. The size of the pores varies – the smaller the pores, the better the filter.

Most current hiking filters have pores ranging in size from 0.1 to 0.3 microns (micrometers) and retain anything larger than that. Some go up to 15 nanometers.

Some filters use only a mechanical filter, and others combine chemical treatments, activated carbon, silver particles or other, for greater efficiency and greater versatility.

I will not get too much into these details here, but it is important for you to know what are the advantages and disadvantages of filters in general.

Advantages :

  • Fast process – allows to purify a large quantity of water rather quickly (according to the filters). The smaller the pores, the lower the flow rate and the longer the process.
  • Ability to drink water directly after filtration.
  • Eliminate particles and sediments.
  • Some remove some of the chemical contaminants – when the pores are small enough.
  • Eliminates most bacteria and microorganisms – this is the case of conventional filters from 0.1 to 0.3 microns or smaller.


  • High price.
  • Maintenance – clean filters, otherwise they clog and biological contaminants develop. This is what prevents active carbon or silver particles in some filters.
  • Weight – which varies according to the filters but which is generally higher than the other means of purification.
  • Most filters do not eliminate viruses (in any case the smallest) – this is the case of conventional filters from 0.1 to 0.3 microns. However, there are filters that can eliminate almost 100% of viruses, either through very small pores or through a chemical treatment associated.
  • You have to pump for most filters – which can be tiring. It’s a bit like using a bike pump. Some filters use gravity or suction and do not have this disadvantage.
  • They can become dirty or clogged. The flow of water can then become very low or even zero.
  • They can crack or be damaged by frost, shock or other. In this case they become ineffective or unusable.

To know :

Some bacteria are not removed by filters of 0.2 microns or more. This is the case of the bacterium responsible for leptospirosis, for example, which has a size of 0.1 to 0.2 microns.

Activated carbon

Some filters are provided with activated carbon. Activated charcoal makes the water clearer, improves the smell and taste, and above all absorbs a large amount of chemicals such as chlorine, iodine, some heavy metals, pesticides, etc. which do not end up in the filtered water. When it is associated with a filter, it decreases the flow of filtered water.

Tip :

It can be difficult to filter water directly from a stream by keeping the tip in the water and avoiding the bottom, where all the particles are. In this case, it is convenient to have a container with which water can be taken and decanted if necessary. The water of this container is then filtered.

Chemical purifiers

See this on: Amazon.com

The principle is the same as for any disinfectant. It involves introducing a chemical into the water and waiting for a while to get rid of the biological contaminants. The difference is that the water must then be drinkable. There are a multitude of different chemical purifiers. For hiking, the most common are the purification tablets.

Advantages :

  • Light – with a few grams you can purify tens of liters of water.
  • Not very bulky.
  • Cheap.
  • Eliminate most bacteria and viruses.
  • Some eliminate microorganisms – depending on the chemicals used.


  • Bad taste – impression of drinking water from the pool.
  • Expiration – the purification tablets have an expiry date beyond which it is not advisable to use them.
  • Long process – waiting time from ½ hour to 2 hours depending on the brand and the degree of disinfection you want. Even longer when the water is cold or cloudy.
  • Must be used with clear water.
  • It is necessary to respect the temperature of effectiveness.
  • Some chemical purifiers do not eliminate all types of microorganisms – some do not eliminate giardia and cryptosporidium for example.
  • Do not eliminate particles.
  • Do not eliminate chemical pollutants.
  • Are not good to be used too much regularly – can damage the intestinal flora.
  • Not recommended for people with blood or glandular diseases and pregnant women.

The characteristics of all chemical purifiers are very different. Here are for example those of two very commonly used :

  • Micropur is effective after 30 min for bacteria and viruses, and 2 h for most microorganisms (including giardia) and amoebae. It contains silver ions, which keeps the water treated for 60 days.
  • Aquatabs is effective after 30 minutes for bacteria, viruses and certain microorganisms (giardia for example but not cryptosporidium). Water can be kept for 24 hours only.

Tips :

  • To eliminate “pool taste”, it is possible to add powdered fruit juice or vitamin C to the treated water. Do this once the disinfection is complete because vitamin C can neutralize the effect of iodine or chlorine.
  • Since it is necessary to wait for the chemical purifiers to be effective, I advise you to take at least two containers to alternate. In this way one of them will contain the purified water, and the other the water being purified.

Ultraviolet radiation

See this on: Amazon.com

This process uses ultraviolet rays that neutralize organisms in the water by preventing them from reproducing.

UV purification systems (portable UV lamp) have been recently developed and treat water through the emission of ultraviolet rays. They usually look like a pen, which is plunged into a container filled with water. Then simply activate and shake for a few minutes to purify the water.

Advantages :

  • Compact.
  • Lightweight.
  • Convenient.
  • Effective – eliminates 99.9% of pathogenic organisms.
  • Fast – 1 to 2 minutes for 1 liter of water.


  • Requires batteries – which is not practical for hiking, especially for long hikes or treks.
  • Requires a clear enough water.
  • High price.
  • Fragile.
  • Does not kill organisms but prevents their reproduction. After UV treatment, avoid exposing the treated water to daylight for an extended period of time – which could allow some organisms to reactivate.
  • Does not eliminate chemical pollutants.

To know :

Some people use the sun to do that. The water that should be purified is contained in a plastic bottle (PET) that has been shaken to oxygenate the water and eliminate some organisms. It is then placed in the sun for 6 to 24 hours depending on the sun. Of course, this method is long, questionable and requires sun. But it’s better than nothing and good to know in an emergency situation.

How to choose your purification system?

The advantages and disadvantages of each system presented above should already give you a good idea of ​​which system is best for you.

Ask yourself first what types of contaminants you may encounter (viruses, chemical contaminants …) and choose from this. Your choice will then depend mainly on your practice and what you prefer- it can be weight, taste, price, versatility, speed, etc.

Some people use system combinations to improve efficiency and better meet their needs.

System combination

Here are some examples :

  • Boiling + filter with activated carbon : boiling eliminates viruses, bacteria and micro-organisms. The activated carbon filter removes chemical contaminants and particles.
  • Filter + chemical purifier (or UV treatment) : the filter removes most bacteria and micro-organisms, and the largest viruses as well as particles. The purifier (or UV treatment) removes the smallest viruses once the water is clear.

What I recommed :

I recommend KATADYN Micropur Forte.

Why ? Most of the time, I go hiking where it is possible to find drinking water at bivouacs – so I do not need to purify all the water I consume. I use it only “just in case” and when there are not enough drinking water points on my route.

The benefit to me is that it virtually eliminates all pathogens, it’s not a big investment, it’s light and I can keep the water purified for a long time. The only drawback is that it does not eliminate chemical contaminants. To be well informed during the preparation of your hike and to collect your water well are two important points.

This was especially important in desert areas where evaporation increases the concentration of chemical contaminants in some waters.

To cook, I use boiling which is convenient, although it does not eliminate chemical contaminants either.

Some additional tips to conclude

You should now know which system is best for you. There are other less commonly used systems like oxidation, distillation or reverse osmosis but I will not present them here.

Some tips in no particular order to finish :

  • This really seems like a basic advice, but read the instructions and features of the purification systems. Each system is different, so it’s imperative that you understand how it works, under what conditions, and what types of contaminants it eliminates. Once you have read them, respect them. Otherwise, drink as much water without purifying it …
  • Pay attention to the neck and cap of the containers. Organizations can hide there. Clean them with purified water.
  • It is always practical to have two minimum containers, whether to decant, pre-filter or purify the water.
  • Have you thought of a backup solution if ever one of your purification systems does not work? A filter may clog or crack, a UV lamp will not work, etc.
  • Pay attention to your hygiene. Filtering your water is necessary, but if you do not have proper hygiene, it does not help much. It would be like having very clean dishes but not washing your hands to eat.

And you, what purification system (s) do you use for hiking? And why ? Share this in the comments!

Leave a Comment