Sawyer Mini SP128 Black Water Filter

The Sawyer Mini is a 40 g squeeze water filter using a 0.1-micron hollow-fibre membrane, tested against bacteria and protozoa and rated for 378,000 litres of use over its lifespan — effectively the life of the filter under normal backcountry use. It threads directly onto standard 28 mm PCO soda-bottle necks and is hydration-bladder compatible, and comes with a syringe, pouch and straw for filtering water in the field. Cleaning is done in the backcountry by backflushing with the included syringe, which restores flow rate when the filter starts to slow down from sediment. The filter is tested against bacteria and protozoa but not against viruses, which matters if you're travelling somewhere with a virus risk in the water supply. It is also not freeze-resistant, so it needs to be kept from freezing overnight or the hollow fibres can crack and ruin the filter. At 40 g it is light enough to carry as a primary filter on any trip, but the squeeze/gravity flow rate is slower than a pump filter, which matters more when filtering water for a group rather than a solo hiker.