MSR TrailShot Microfilter

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

Bacteria and protozoa at 0.2 µm, to NSF protocol P231 and the US EPA guide standard (MSR). A named standard for bacteria and protozoa, so 4. The manual says it does not remove viruses.

How fast clean water comes through when it is new. Real flow drops as it clogs: see Ease of use. 4: A bit below average.

MSR gives 1 L/min (a litre in 60 seconds), new filter, clean water. 0.6 to 1.19 L/min. UKC gives the same figure.

How much it adds to your pack. 7: Better than most.

142 g (MSR). 90 to 149 g. It needs no bottle to drink from: you can drink straight from the spout or fill your own.

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.

Dip the hose, pump with one hand, drink or fill. UKC (5) handed it to friends and clients with no instructions and they all worked it out. Outside (5) calls it as simple as a filter gets, with no parts to lose. OutdoorGearLab (3) found it easy to clean and back-flush, but more tiring than a gravity filter for large amounts of water. Average 4.3 out of 5, so 9 out of 10, with reviewers 2 points apart. UKC and OutdoorGearLab reviewed it in 2017, and Outside first published in 2017 and updated its page in 2024. MSR's figures today are the same as in the UKC review (142 g, 1 L/min, 2,000 L) and we found no announced redesign. OutdoorGearLab's 10-point scores are halved and a half rounds down (9.0 becomes 4, 8.0 becomes 4, 7.0 becomes 3, 5.0 becomes 2), the same as on other Fellkit pages.

Reviewers disagree on this.