We’re lucky to have probably the world’s finest water in Scotland, so most hillwalkers think nothing of swigging straight from the burn – in fact, it’s one of my greatest outdoor pleasures (especially when combined with a local single malt…). Even in Scotland precautions need to be taken though, extracting water downstream of a dead sheep is never wise, and ensuring that you’re well above farmland and any surface run-off is a good move. Risks from contaminated water include waterborne pathogens – protozoa (causing, for example, cryptosporidiosis), bacteria (eg. dysentery) and viruses (eg. hepatitis). There’s also the matter of particulate suspended in the water – nobody likes drinking muddy water. If there is a requirement to treat dubious water there are several methods available to the hillwalker: boiling, chemicals, filtering and UV treatment. As always, each has pros and cons – boiling requires the use of fuel and results in warm water which is unpleasant to drink immediately, chemicals like chlorine dioxide are lightweight and relatively easy to use, but require a time delay before drinking. They can also impart taste to the water. Filters are efficient and also remove particulates from the water – but they can be heavy and require unclogging and maintenance, though bottle-mounted filters are particularly easy to use and produce ready-to-drink water. UV treatment creates small quantities of treated water at a time – 0.5 or 1 litre – by damaging the DNA of microbes and pathogens (even viruses), so they cannot reproduce and cause illness. The water is ‘ready’ quickly, doesn’t taste of chemicals and there’s no pumping or complicated equipment required. However – to allow the UV light to reach all the water and work properly they can only be used with small quantities and it does nothing to remove particulates from the water so a pre-filter is required. They are also dependant upon battery power.
The SteriPEN Ultra (RRP £96, 140g) is a perfect example of a UV water treatment device, with an LED dispay that makes things practically idiot proof. To use, fill a container with either 0.5 or 1 litre of water, switch on the pen-shaped device and insert into the water. The pen will light up and a screen will display the pen moving around, reminding you to keep it moving to ensure as much water comes into contact with the pen as possible, as well as a countdown timer (45 to 90 secs). Once the timer runs out, a smiling face confirms that the water is ready to drink. It’ll then confirm the remaining life of the bulb (approx 8000 treatments from new) as well as the battery life. There are a few situations that could cause a sad face – if the pen isn’t in the water long enough, the battery is too low or the lamp has expired or become damaged. In cold weather the lamp needs time to warm up and a few seconds will be added to the timer. It’s as simple as that.
I like the rechargable battery – charging via a micro USB socket as found on many mobile phones – meaning it can be charged from a computer, wall socket or even a solar charger to give about 50 treatments. I’ve got a USB adaptor for the 12V cigarette lighter in my car, and can charge my headtorch, phone and now the SteriPEN using the same lead. It’s expensive, but invaluable if travelling in an area where water quality is variable. Think of it as a protozoa insurance policy.