WATER TREATMENT PRODUCTS

1. Type

Hollow-fibre filters are practical for backpacking use, protecting against bacteria and protozoa. Filters with a pore size below 0.02 microns can also remove viruses

(less essential in the

UK). These filters must never be stored in freezing conditions. Other options include UV treatment (which can also destroy viruses) and filters containing activated carbon or ionexchange technology (to reduce chemicals).

2. Design

Filters can typically be used to drink through directly (from the source, or from the included bottle/ bladder) or to filter into a separate container. Some filters rely on gravity, or the user squeezing the ‘dirty’ bladder; others use a lever pump.

3. Ease of use

Filters that are slow to use, or require a lot of elbow grease, are less convenient. Look for fast and reliable flow rate.

4. Maintenance

Filters can clog if used in silty or dirty water, so should be easy to clean or backflush. Some designs have cartridges that need to be replaced after a certain amount of use. Battery-operated products should offer good battery life.