Water Filters and Bottles

Filter or purifier, the freezing trap, and the backup that always works.

Updated

Clear water is not clean water, and the consequences of assuming otherwise outlast the trip.

Filter or purifier

For North American and European backcountry a filter is enough, because waterborne viruses are rare there. For travel in the developing world, or anywhere human sewage could be upstream, you want a purifier.

What changed: squeeze filters took over

Hollow-fibre filters from Sawyer, Katadyn and others weigh 60 to 100g, cost little, screw onto a bottle or soft flask, and filter as you drink. They replaced pump filters for solo hikers, and a pump now makes sense mainly for groups or genuinely silty water.

The failure mode nobody warns you about

Freezing destroys a hollow-fibre filter. Ice cracks the fibres invisibly and the filter then passes everything through. Never leave one in a cold tent or a car overnight in winter, and replace any you suspect. This is the most important sentence on this page.

UV and chemicals

UV devices treat viruses, add no taste and need clear water and a working battery. Chlorine dioxide tablets weigh nothing, last years, handle viruses, and cost you thirty minutes of waiting. Carry tablets as a backup whatever else you carry, because a clogged filter or a flat battery is a trip-ending problem otherwise.

Bottles and bladders

A bladder means you drink more because it is effortless, which matters in heat. It is also hard to refill mid-walk and a nuisance to dry. Bottles in reachable side pockets are easier to fill and easier to gauge. If you use a bladder, rinse and dry it after every trip and store it in the freezer; a damp bladder in a cupboard grows exactly what you would expect.

And the free step people skip: collect from moving water, upstream of trails and camps, and let silt settle before filtering. It doubles the life of any filter.

Kept current

The reviews (41)

Written at the time, about gear that in most cases is no longer made. Useful for what the writer noticed, not as a shopping list.