Katadyn BeFree Gravity 3 L Water Filtration System

What it removes from water, and how well that is proved. 8: Clearly better than most.

Removes bacteria and protozoan cysts with a 0.1 µm hollow-fibre membrane. Katadyn's manual says it meets the US EPA's microbiological water purifier standards for bacteria (99.9999%, Klebsiella terrigena) and protozoan cysts (99.9%, Giardia and Cryptosporidium): a named standard for bacteria and protozoa at 0.2 µm or finer, which is the Protection 4 line. The manual says it does not remove viruses, so it is not a 5.

How fast clean water comes through when it is new. Real flow drops as it clogs: see Ease of use. 7: Better than most.

Katadyn gives up to 2 L/min, in the 1.8–2.49 band. Testers found it fast, but the figure is a best case: JEL Reviews saw a strong flow from muddy water, and The MTB Lab and SectionHiker call it fast, while the membrane slows as it loads and there is no backflush. Banded on Katadyn's figure.

How much it adds to your pack. 6: A bit better than average.

192 g for the 3 L reservoir, filter, hose, strap and clamp (Katadyn manual), in the 150–299 band. Ultralight Outdoor Gear lists 206 g without the storage bag.

Filling, squeezing or pumping effort, how fast it clogs in peaty or silty water, and how easy it is to clean. 9: Among the best you can buy for this.

The MTB Lab (4) used this kit at Havasu Falls: fill, hang, filter and drink, but the pinch clamp was fiddly, it needs a branch or someone to hold it, and the bag is hard to dry. JEL Reviews (5) filtered muddy water with this kit and cleaned the filter by dipping it in water: the easiest filter the reviewer had used. Filter-only sources: SectionHiker (5, sample sent free by Katadyn) and The Outdoor Gear Review (5) tested the earlier 3 L BeFree bag with the same filter, not this hose kit, so we count only what they say about the filter itself (speed, cleaning, no backflushing): fast, swish or shake clean. Average 4.8 out of 5, so 9 out of 10.