Sawyer Mini SP128 Water Filter

The Sawyer Mini SP128 is a hollow-fibre squeeze filter rated to an absolute pore size of 0.1 micron, tested against both bacteria and protozoa, and weighing 40 g. It attaches to a soft bottle or standard drink bottle for squeeze filtering, works as a straw for drinking straight from a source, and threads inline onto a hydration bladder for filtering on the move. Sawyer rates the cartridge for up to 378,000 litres, which in practice means the filter itself will outlast most trips if it's cared for - cleaning is by backflushing with the included syringe, and it can be flushed in the backcountry without extra tools. It is not freeze resistant, so on cold-weather trips it needs to be kept from freezing overnight or the fibres can crack and ruin the filter. At 40 g it suits thru-hikers and backpackers filtering from streams and lakes on multi-day trips, though the squeeze flow is slow enough that some hikers prefer a gravity or pump setup when filtering large volumes for a group.