0.2 Micron Water Filter

5 Rob
I bought this 2- 3 years ago for use on scout backpacking trips and emergency use during hurricane season . The thought was to have zero worries with water supply no matter where I was . The troop had another MSR filter with lower filtration pumping 1L per minute . Scouts became impatient and those were quickly abandoned to use mine . Win# 1! We recently took a long distance backpacking trip and most groups used micropur tablets for sterilization, but not wanting to wait used this filter instead for immediate water consumption without an altered taste . Water supplies were typically streams or in some cases cisterns from rain collection or pumps which still needed sterilization . Win# 2! One camp ran out of water in their cistern with zero streams for decent water nearby . I said not a problem and we filtered out of a cattle pond full of all kinds of bugs, algae and things no one wanted to deal with . This pump had zero issues and no one got sick . Win# 3! Lessons learned: most of the time, filtration just occurred over one or two days, this last trip was longer . If the nalgene was too tight, it would cause leaks between the filter and the water bottle . The same occurred if the gray ring at the bottom was too tight to the red cylinder on the filter . Loosening those connections brought everything into alignment with no leaks . A gentle tightening was all that was needed . After each trip, I do pump some clean water through the filter thinking one or 2 extra liters wo n't impact the life of the filter . I hang the filter to dry out the entire length of hose, and invert the filter section with fibers so it drains as well . I 've had zero issues with the performance of this filter and have full confidence whenever it is used . I still carry the maintenance kit with me, but it has yet to be used .

5 John V.
WE have been using the Guardian Purifier for several years now and just purchased out third one . We use it in a wilderness camp for up to 9 people for two weeks duration . We have never had a problem with the device or supplying ample water for each group . Several of our guests have purchased on for their own use after using the Guardian in our camp .

5 Elizabeth K.
Love the peace of mind! Easy to use& fills bottles quickly . We wanted one filter that we could use on any trip no matter where in the world, and no back- flushing makes this a dream .

5 Matt R.
I got this as a splurge for a 5 day loop in Tanner and out Grandview in April when the water was running high due to the past few years of Norovirus being prevalent in 2021 and 2022 for a group of 4 and it delivered with just a few minor issues . We did settle water for 1- 2 hours before filtering except for one day to filter directly after pulling from the river but I did n't note a difference in performance . For notes- we had the issue of leaking out the large filter housing O- ring when someone in the party overtightened it but we were able to resolve that after playing with it a bit( had us worried for a moment we were going to be onto tabs or boiling when it first started!!!) so it might be nice to make that note more visible in the manual as it was very easy to accidently do( I read on the website before going) . We also had some leaking out of the back of the pump head as I have seen in other reviews( just a few drops here and there generally) and I was not able to resolve that even with slow pumping . Here I just made sure that the clean water bottle was fully attached so any drip from the back of the pump head would not go into the bottle . I would say we generally filtered much slower than 2 . 5 L/min even with clean water( more like 0 . 5- 1 L/min) as I had read that a common failure was the pump handle pin can break on this system so we generally tried not to apply too much pressure to the handle but instead ran slow and constant and tried to make sure not to exert too much pressure at the top and bottom of the pump rise . I overall still prefer gravity filters as they are just so much easier when we filter most of our water at camp( yes I am lazy:) but for the Colorado River and something that handles virus removal I was pleased with the purchase . Thanks to the team there at MSR and hopefully see everyone out there on the trails

5 Andrew F.
I appreciate the filter speed and filtration . I think that all the people complaining about their broken filters are ungrateful . I ’ d bet they never went on a 30 mile out and back with 6k vert . The unit is light for what it is . This is an excellent design . They designed a lightweight product that works when perfectly when used correctly . There is a notch between the bottom rubber grip and the frosted main body of the filter . Tighten the grip to the main body until you reach an obvious notch . Then tighten the bottle onto the filter without touching the frosted plastic . It will work flawlessly .