Running out of water on a hike is not uncommon. Don't panic — there are solutions for obtaining safe drinking water. But how do you purify water? Boil it? Treat it with UV rays? Use chemical purification tablets? Use filters? Each of these methods for purifying water while hiking has its advantages and disadvantages, detailed below.
It's also worth remembering that the boiling point of water depends on the altitude you're at. If you're hiking somewhere close to sea level, you can let the water boil for one minute — that's enough to kill bacteria, as water boils at 100°C at this altitude. The higher you climb, the lower the boiling point of water. But at these lower temperatures, bacteria are not killed immediately and require a longer boiling time. At 4,500 metres, water boils at 85°C, so you'll need to keep it boiling for several minutes to eliminate micro-organisms. If you're climbing Everest, water boils at just 70°C, meaning you'll need to keep it at a rolling boil for at least half an hour.
However, organisms are not killed — they are simply rendered unable to reproduce. This is also why UV-treated water should not be exposed to sunlight for too long, as this can reactivate the organisms. The main drawback of UV purification is that it is not effective against chemical pollutants. Furthermore, portable UV lamps are not within everyone's reach, as this remains a costly technology.
The drawback of filter treatment is that it rarely eliminates all viruses. Very small pores are needed to remove all viruses from the water — or the filter treatment must be combined with a chemical treatment.
How to purify water while hiking: bringing water to the boil
It's an age-old method: boiling water to kill the micro-organisms and bacteria it contains. The process isn't difficult and requires no specialist equipment. Simply build a fire and bring the water to the boil. If you need to cook at the same time, you can kill two birds with one stone. However, be aware that boiled water tastes flat. Beyond the taste, it's also worth noting that the water is warm and not ideal if you want to cool down — unless you wait for it to cool.
It's also worth remembering that the boiling point of water depends on the altitude you're at. If you're hiking somewhere close to sea level, you can let the water boil for one minute — that's enough to kill bacteria, as water boils at 100°C at this altitude. The higher you climb, the lower the boiling point of water. But at these lower temperatures, bacteria are not killed immediately and require a longer boiling time. At 4,500 metres, water boils at 85°C, so you'll need to keep it boiling for several minutes to eliminate micro-organisms. If you're climbing Everest, water boils at just 70°C, meaning you'll need to keep it at a rolling boil for at least half an hour.
How to purify water while hiking: UV purification
Today, highly advanced technologies exist for purifying water. Portable UV lamps are proof of that. The size of a pen, these lamps are highly effective and extremely practical. Simply switch the device on and move it around in all directions inside a container full of water — job done. Purifying one litre of water takes just one to two minutes of treatment. The biggest advantage of this water purification technique is that the device is fast and compact, as well as being very lightweight. Almost all pathogenic organisms in the water are eliminated during the process.
However, organisms are not killed — they are simply rendered unable to reproduce. This is also why UV-treated water should not be exposed to sunlight for too long, as this can reactivate the organisms. The main drawback of UV purification is that it is not effective against chemical pollutants. Furthermore, portable UV lamps are not within everyone's reach, as this remains a costly technology.
How to purify water while hiking: filters of all kinds
Filters can also be used to purify water. The principle is simple: water is passed through fine-pore filters, which retain particles and micro-organisms, leaving pure, drinkable water. Various types of filters are available: cartridge filters, fibreglass filters, membrane filters, ceramic filters, and so on. Generally, filter treatment is fast. However, treatment time also varies depending on pore size — the smaller the pores, the longer the treatment. That said, it is a highly effective process: almost all bacteria and micro-organisms are captured by the filters. After treatment, the water can be drunk directly. It's an ideal solution if you need to cool down. However, filters require very rigorous maintenance. As the process involves retaining micro-organisms inside the filter, if it is not cleaned regularly it can become blocked and allow biological contaminants to develop.
The drawback of filter treatment is that it rarely eliminates all viruses. Very small pores are needed to remove all viruses from the water — or the filter treatment must be combined with a chemical treatment.
