Fastest flowDrink as you walk, no squeezing at a tap
Katadyn BeFree 1L
The fastest flow of any soft-bottle filter and it collapses to nothing when empty — the flask is the weak point, and a pinhole in it ends the system rather than the filter.
Best overall
Bacteria and protozoa out, for the whole trek, for the price of two lodge bottles
Sawyer Squeeze Water Filter
0.1 micron hollow fibre, ~85 g
4.7 on Amazon
Effectively unlimited water for the cost of a couple of bottled waters, and it threads straight onto a standard bottle — it does NOT remove viruses, so pair it with chemical drops on trails below villages.
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What you get
- Removes giardia and cryptosporidium, the two that actually ruin treks
- No batteries, no waiting, no taste
- Lasts years if you backflush it
What it costs you
- Viruses pass straight through
- Ruined permanently if it freezes with water inside — sleep with it
- Flow slows unless you backflush
Do not buy this if: Anyone treating it as complete protection. Below the last village, add drops or a UV pen.
Treks we recommend this for
Not every route needs it. These are the ones where our guides would put it on your list.
The alternatives
Everything else we recommend in filters & purifiers, including the ones we think suit a different trekker.
Fastest flow
The virus half of the answerWhat you add to a filter, not instead of one
Aquatabs Water Purification Tablets
Handles the viruses a filter misses and weighs nothing, which is why we recommend carrying both — it does not touch cryptosporidium, and it makes the water taste of a swimming pool.
Simplest complete answerViruses, bacteria and protozoa in one press
GRAYL GeoPress Purifier
The only single item here that removes viruses as well as everything else — you pay for it in weight, in cost, and in a cartridge that needs replacing every 250 litres.