Best Water Filters and Purifiers For Hiking and Backpacking
The opening point stands: clear mountain water is not necessarily clean mountain water, and the consequences of assuming otherwise last longer than the trip.
Filter or purifier, which is the distinction that matters:
- A filter physically strains out protozoa like giardia and cryptosporidium, and bacteria. It does not remove viruses, which are too small.
- A purifier also deals with viruses, using chemicals, UV or a much finer membrane.
For North American and European backcountry, a filter is enough. Viruses in wilderness water are rare there. For travel in the developing world, or anywhere human sewage may be upstream, you want a purifier.
What has changed most since 2010: hollow-fibre squeeze filters took over. Sawyer and Katadyn's BeFree weigh around 60 to 100g, cost little, screw onto a bottle or a soft flask, and filter as you drink. They replaced pump filters for most solo hikers, and a pump now only makes sense for groups or genuinely silty water.
The failure mode to know: hollow-fibre filters are destroyed by freezing. Ice inside the fibres cracks them, invisibly, and the filter then passes everything. Never leave one in a cold tent or a car overnight in winter, and replace any you suspect.
Carry chlorine dioxide tablets as a backup whatever else you carry. They weigh nothing, last years, deal with viruses, and work when a filter clogs or a UV device is flat. The only cost is waiting thirty minutes.
And the free step everyone skips: collect from moving water, upstream of trails and camps, and let silt settle before filtering. It doubles the life of any filter.
Part of the guide to water filters and bottles.