Masterclass
How to make wild water safe
If you spend a few days on the hill you’ll need to find enough water to stay hydrated. But while mountain streams might look tempting you should never drink water from them without treating it first, as even the most remote streams can carry pollutants. Rob Johnson shares his top five ways to treat water and make it safe to drink. 1 BOILING
Reliable and simple if you’re carrying a stove. A 1-minute rolling boil kills protozoan parasites and most bacterial and viral pathogens. As my friend Huw would say, “lots of bubbles, no troubles”. Filter out any sediment before boiling and remember it doesn’t neutralize chemical pollutants.
2 CHLORINE TABLETS
Chlorine tablets kill bacteria, viruses and giardia, but not protozoan parasites. They’re easy to use and popular for overseas trips – simply drop the tablet in water and wait. If the water is over 16°C then it can be safe to drink within about 30 minutes, but colder water may need to be left overnight. It will taste a bit like a swimming pool, so add squash for a better flavour.
3 FILTERS
Filters tend to be lightweight, easy to carry and treat water more quickly than chlorine, but the results aren’t as conclusive as boiling. They promise to remove 99.99% of bacteria and protozoa but don’t remove viruses, so should ideally be used in conjunction with one of the other purification methods.
4 ULTRAVIOLET LIGHT
My choice of purifier is a UV pen which eliminates 99.9% of bacteria, viruses and protozoa. I filter the water first to remove any larger physical pollutants and have found that a single set of batteries will last for a month-long expedition.
5 GO HIGH
With all of these methods, you stand a greater chance of remaining healthy if you collect your water as high as you can. The closer to the source you are, the less likely it will have been polluted on its journey. Pay special attention to which animals are grazing nearby, and check the stream for at least 20 metres above you for dead animals or other people camping higher up.