How to buy water treatment
26 June 2008 15:54
Even the cleanest-looking water can carry disease. But should you boil it, filter it or purify it to make it safe to drink?
Do you need it?
In the UK you can safely drink water from taps and even some mountain streams. But if abroad you need to take much more care as only 0.8 per cent of the world’s water is safe to drink untreated.
Service life
All filters clog up eventually so they will need replacing, often at quite a high cost. So consider this when choosing a system to purify large amounts of water.
Taste
Iodine leaves a nasty taste in the water, so better filters use carbon or silver (or other methods altogether) to do away with it.
Flow rate
If you don’t want to wait all day for your water, then a fast flow rate is important. But if you only expect to purify water occasionally then a slower method may be acceptable.
Ease of use
If you are using the purification system frequently, ease of use will be a major factor. Otherwise you could save money and weight in your rucksack by choosing a system that may be less efficient.
Treatment options
Vaccination Jabs available before travelling will provide protection against some viruses such as polio and hepatitis, and bacteria such as cholera.
Boiling
Boiling water for 5-10 minutes will kill all bacteria, parasites and viruses. But add 1 minute for every 300m (1,000ft) that you are above sea-level.
Iodine
Iodine in small doses is effective against all bacteria, parasites and viruses, but on its own it will not remove any solids. However iodine is toxic and requires careful use as 2-4g of it can kill. Pregnant women and those with thyroid problems also need to consult their doctor before using it, and in any situation iodine should only be used for a maximum of 30 days regularly. So pure iodine is best for emergency use only. Small bottles of iodine tablets are available from many outdoor shops. For stockist details contact Lifesystems (– tel. (01189) 811433) or Nomad Medical (– tel. (020) 8889 7019).
Chlorine
Chlorine kills bacteria and viruses but is not effective against cysts such as Giardia, which is often the main problem in mountain streams of the UK. Packets of chlorine tablets are available from many outdoor shops.
Filtration
Filters force water through small holes around 0.0002mm (0.2 microns) in size while trapping contaminants. To remove viruses some chemical treatment is also required, in the form of iodine. So most water filters are designed to be used a few drops of iodine that are added to the water before it is filtered.
Purification
Water purifiers give water a dose of iodine as they filter, but the taste of the iodine can removed by other chemicals such as carbon or silver that may be built into the unit.
UV light
This destroys viruses, bacteria and protozoa – including Giardia and cryptosporidium – in seconds.
Packed size & weight
A few iodine tablets are ideal for emergency use, small purifiers are great for occasional use, while heavy and bulky filters and purifiers are best restricted to daily use.
Contamination
When you buy a treatment system the packaging will state which contamination it is effective against. The three main groups are:
Bacteria – cholera, E coli (Africa, Asia, UK, USA).
Viruses – hepatitis, polio, rotavirus (Africa, Asia, South America)
Parasites/cysts/protozoa – Giardia, cryptosporidium, (Africa, North America, South America, Australia plus any mountain streams that flow near wild camping areas or popular footpaths anywhere in the world including UK and Western Europe)
