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THE GREAT OUTDOORS: MAGAZINE

The Katadyn Be Free came out several years ago, but is worth taking a look at again as in some respects it still hasn't been surpassed. This is a hollowfibre filter that screws into a standard softflask (600ml and 1 litre versions available). You fill up the flask from any water source, then either drink through the filter or squeeze into another container. The filter will protect against bacteria and protozoa but not viruses. The soft flask has a stiffened wide mouth and is easy to fill.It has superb flow rate - Katadyn claims up to 2 litres per minute, and I've found this to be roughly accurate. You can drink freely through the filter without having to squeeze much, and filtering into containers is not a chore. If flow rate drops after filtering dirty water, cleaning is also easy. You don't need to backflush it - you just swish it in a stream. This is effective unless the filter has become completely clogged, in which case you can backflush using a separate bladder filled with clean water. In practice this is almost never needed. The only downside is that, after extended hard use, the soft flask can develop leaks near the top seam. This happened to a previous sample but has not affected the current one I've been testing. Overall, the simplicity, convenience and extremely good flow rate of the BeFree make it ideal for most backpackers. It's become my go-to filter.