i.e. no biolite shills allowed.

This filter right here. It is the shit. Compact, removes everything but heavy metals, and crucially it never needs new filter cartridges. That's what sold me on it.

You just flush water through in the other direction to rinse it out once in a long while. It's based on the same nanofilter tech as kidney dialysis machines.

Pro tip: Instead of using the squeeze pouch, attach an empty 2 litre plastic soda bottle to either end. The bottom one will need a hole drilled in the cap to stick the spout through, also a hole near the top for displaced air to escape.

The top bottle doesn't need its cap (will screw into the filter) but needs a hole drilled on its bottom (which will be at the top when it's inverted) so air can enter to displace water as it drains downward through the filter.

Presto, now gravity does all the work. Fill the top bottle, keeping one finger on the hole, then attach the filter, flip it and stick it into the bottom bottle. Then let it work like an hourglass. Go on a hike and by the time you come back you have 2 litres of filtered water to cook, drink or wash with.