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MSR Guardian Purifier System


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    • Smoke, One Size

    10 Reviews


    Enjoy the freshest water you've ever tasted.

    Drinking straight from crystalline mountain streams is nice in principle, but a lot less awesome when you end up running for the bushes every five minutes for the rest of the trip. There are plenty of ways to help save yourself from waterborne bummers, but none that are as effective, easy to use, and reliable as the Guardian Purifier System from MSR. Developed for, and in conjunction with, the US military, the Guardian uses new Hollow Fiber technology to filter out just about everything (protozoa, bacteria, particulate, and even viruses), so you can sip fresh, clean water without first checking that you packed extra TP. The Guardian has an easy pump-action design that can filter up to 2.5L per minute, and an ingenious self-cleaning design—10% of the water from every stroke flushes contaminants from the filter, so it never gets clogged or becomes less effective. The wastewater is discharged through a tube that runs parallel to the intake, so it empties easily back into the water source. MSR also included a water-bottle adapter for easy fill-ups, and a cartridge life indicator that lets you know when it's time to switch (although the included filter is good for at least 10,000L, so it might be a while before it's that time).

    • Hollow Fiber filter
    • Self-cleaning
    • Pump action
    • Effective against protozoa, bacteria, viruses, and particulate
    • Water bottle adapter
    • Cartridge life indicator
    • Item #CAS008I

    Tech Specs

    Purifying Element
    Hollow Fiber
    protozoa, bacteria, viruses, particulate
    Pore Size
    0.02 micron
    Cartridge Life
    10,000+ L
    2.5 L / min, 30/35 strokes / L
    Field Cleanable
    water bottle adapter, cartride replacement indicator
    8 x 5 in
    Claimed Weight
    1 lb 1 oz
    Recommended Use
    camping, backpacking
    Manufacturer Warranty
    1 year

    Tech Specs

    • Reviews
    • Q & A

    What do you think about this product?

    Have questions about this product?

    Wont leave home without it.

    • Familiarity: I've used it several times

    I used this on a group trek to Everest Base Camp in Nepal where the rivers, streams, and glaciers, while beautiful, are teeming with human and animal waste. The guys in the group all had various methods and systems of purification, and by day 3 they were all lining up while I pumped their water from the Guardian. They were all so impressed that they were abandoning their systems and looking to buy the Guardian when they returned. The shear ease, reliability, and rate of production makes the Guardian worth the extra money. If you are planning on traveling anywhere that requires a water purification system, or even filtering for that matter, you won't be disappointed with this pump.

    Clear in look and taste for once

    • Familiarity: I've put it through the wringer

    On the pct my 3 liters were running low so I decided to test this on a really nasty small pond in Oregon. To my surprise the water went from a dark green/brownish color to completely clear. Ok it's going to taste like crap though right? Not even a little. It tasted great! Better than the smart water bottle I still had partially filled with hotel water. I ended up using it everywhere even though I really may not have needed to just because it was so fast and easy, why not? It was always worth it, even if simply to improve to the taste of my chicken teriyaki meal I was about to rehydrate:) I highly recommend this purifier! I will always be looking anywhere else to shed ounces as the Guardian will be an essential part of my backcountry kit for years to come.

    Amazing water treatment system.

    • Familiarity: I've put it through the wringer

    I was able to get this purifier through MSR on a pro deal discount and it is in my opinion the best way to treat water out there. I am a volunteer in Uganda and have to treat all of my drinking water so this being a 1 step solution makes it as easy and quick as possible. I've been using this everyday since June (a little over 8 months as of this writing) and have had no issues. I normally retrieve water from a clear water source but I have also used it retrieving water from murky lakes and streams when back packing and it always gives clear, safe, good tasting drinking water.
    It's not the smallest thing to pack, but this minor negative is by far out weighed by all the perks.
    - Never having to back flush
    - Removes virus and bacteria, which as someone who teaches water sanitation here geeked out about that they have finally made a filter type purifier, making a one step method to safe drinking water. No more boiling or UV required.
    -Is pretty quick, I can feel up my nalgene bottle in little time.
    - One filter cartridge last a very long time. For me this was a big reason to get it. Getting things shipped to me here in Uganda isn't the easiest so I wanted something that would last a while and this so far has.
    Overall. Get it, it's expensive but that's just because it's that awesome.

    Sweet sucker!

    • Familiarity: I've used it once or twice and have initial impressions

    I used it this weekend in the melting snow. It pumps super fast and the water is great! I love mountain water! it was way lighter Then I thought it would be too. With it being military grade i thought it would be super heavy. Not so.

    Life expectancy -- 15 liters.

    • Familiarity: I've used it once or twice and have initial impressions

    I purchased the MSR Guardian after speaking with MSR on 3 different occasions as well as several local shops. All assured me the Guardian was the perfect filter to take to the Grand Canyon to filter silty water. After filtering 15 liters of moderately silty water the filter died, all the water was being returned via the outlet hose. Following the directions, I cleaned the pressure relief valve but found it to be perfectly clean. The next step in the instructions is to replace the filter, unfortunately not an option deep in a remote section of the Grand Canyon. The filter appeared to be perfectly clean.

    When I called MSR, they admitted the Guardian has problems with silty water and was told “we’ve had problems with this pump”. Of course this is unacceptable since they advertise this pump as being made for “worse case sediment”. This ruined a 7 day backpack and forced us to hike out and drive 50 miles to purchase some treatment tables. I should have had a backup but everyone I talked to about this pump assured me of it's reliability. I expected much more of this product and from MSR Customer service.

    Robert P, thanks for your review. We are sorry to hear that you had a poor first experience with the Guardian. After reviewing your particular Guardian it appears that a great deal of ultrafine, clay-like silt entered into the purifier and sealed off the filter head. While the integrity of the filter was not compromised (would not pass through virus, bacteria, or protozoa), the reduced flow was on account of this high sediment level. High levels of ultrafine sediment will impact the filter more quickly than other types of particulate matter. When dealing with this type of water, it’s best to let particulate matter settle out of solution first, either in a small pool or a bucket, if available.

    MSR’s customer service team strives to provide as much information as possible to either help fix the problem, or get the unit in question back so our engineers can identify the issue. As the Guardian is a fairly new product, we ask that the customer provide as much accurate information about the scenario under which the problem occurred so we can work to prevent similar issues for other customers in the future or at least educate customers on proper usage. As all of our products have a limited lifetime warranty, we will either fix or replace the product in question.

    Mmmm Water

    • Familiarity: I've used it several times

    When I look at filters, I take flow, maintenance, and what gets eliminated into consideration. I'm not much of an ultralight backpacker, so weight isn't a huge deal. When it comes to my top considerations, the Guardian wins at all three.
    First, it's fast! I've been upset with several other filters that claim to pump water at 1L/min, and 5-10 minutes later my Nalgene still isn't full.
    The Guardian though, easily filled my Nalgene within 30 seconds of continuous pumping. I'd even fill my 10L Dromedary bladder with this thing! The handle is long, providing better leverage so you don't get fatigued as fast. The pre-filter also doesn't have to be completely submerged to suck water, so you don't have to worry about managing the hose to get the pump working at full flow.
    Second, the upkeep of this is so easy. Just toss the hose pre-filter in the water, pump what you need, then wrap it back up. There's no need to flush the system, wipe the filter element, etc.
    Finally, the Guardian filters all of the nasties! I'm 100% confident drinking the water that this filter pumps out, as long as I'm not directly downstream of a sewage treatment plant (More of a personal rule than a fear of the Guardian not doing its job).

    MSR Water Research Lab

    Go behind the scenes of MSR's world-class water research lab to learn about the work our on-staff water scientists do.

    The lab is located at our Seattle headquarters, in close proximity to our production lines, and is staffed by five scientists with advanced degrees in chemical engineering, biochemistry, microbiology, environmental science and cellular and molecular biology. The world inside this small space is fascinating, with an incredible amount of scientific knowledge. Here’s a look inside.

    The Guardian is fantastic

    • Familiarity: I've used it several times

    The system is extremely easy to use while in the field. You unravel the hose which wraps around the housing of the Guardian and then just drop it right into your water source. From there you can attach a Nalgene or I use the Dromlite for backpacking. It's a bit heavy at about 1 lb., however I think the peace of mind is worth it. I also don't have to deal with the slow output of Sawyer every time I take a drink, which drives me nuts. Plus this is actually a purifier and is blocking viruses where others are just filters and don't block as many nasties. With all of these new viruses coming out I think it's becoming essential to actually purify the water.

    MSR has great customer service and builds great products. It's great to have an all in one solution for purifying water.

    High Quality H20

    • Familiarity: I've put it through the wringer

    About a few months ago MSR connected with me to test and review their new water purifier, the MSR Guardian. Naturally I was super stoked to work with them on this but also really curious about how it was going to perform and see if it lived up to all the hype.

    From taking the purifier apart to testing it in gross local water sources here in Salt Lake City (seriously, one of them was worse than the water you'd find in the mountains) I can say my stoke is high on this new device. It definitely lives up to the standards that we all have come to know of MSR products.

    If you've got questions about the MSR Guardian purifier feel free to contact me and I can work with you to get your questions answered and to see if this is the right purifier for you.

    In the past I've used a range of water treatment products from a variety of brands. Each having various aspects that I was a big fan of but also having major pitfalls. Some had ceramic filters that required scrubbing to maintain cleanliness, which resulted in further wear on the filter. Other pumps had lots of parts and various intake and outlet hoses that couldn't go near each other. The worst were the iodine tablets that left behind a terrible taste in the water and require me to wait more time that I would like. Rather than rambling on about all those, I'll break down the MSR Guardian purifier and if you see something I've left out and want to know about, definitely let me know and I'll revise the review as questions come up.

    This is one of the easier water treatment devices to manage when it comes to assembly. Take the purifier out of the storage bag. Take out the hose that has the pre-filter attached to it. Align the hose with the spring with the top opening and press on. Unscrew the cap on the bottom of the device and screw on a wide mouth water bottle.

    The MSR Guardian comes with a storage bag that has a zippered opening. Put the cap on the bottom of the purifier and undo the hoses. Then put it all in the bag and pack away in your backpack.

    At first I thought the handle on the pump was a bit unnecessarily big from a storage and transporting view. But when pumping a few gallons of water the extra leverage is real nice. Plus the action on the pumping mechanism is super smooth. I haven't used another pump that provides as little resistance and is as smooth as this purifier. Plus with the water bottle screwed on to the bottom of the purifier there is no awkward balancing of the system while trying to keep the intake hose in the water/out of the dirt and the outlet hose inside the water vessel you're pumping into. The next big aspect that makes pumping easier (gives you some piece of mind) is the pre-filter.

    In the MSR videos their testers filter some really murky water. With the local sub-par water source here in SLC that I tested the purifier in, I saw how awesome the pre-filter worked. It is really awesome to let it either draw from the top of the water source and not suck in just air. The material they used works really well once it's wet to not draw air into the intake tube. If the pre-filter hits the bottom of your water source it is awesome that you don't need to worry about what aside from water is being drawn into the intake hose. Plus the outlet hose pushes water out of the system to keep the pre-filter clean.

    I'm normally a backpacker that wants to have one of the smaller and lighter packs that I can get. This device would take up a bit more room than I'd like. But it does more than the other water treatment devices I've used.

    Up Keep:
    One of the biggest upsides to the MSR Guardian purifier is that this device really requires almost no maintenance. Other devices I've had require scrubbing, exposure to air for cartridges to dry out, proper storage, etc.

    Just pump water and the occasional integrity test.

    If you've got questions reach out and I'll help answer your questions.

    High Quality H20

    Performing the Integrity Test

    The Guardian Purifier was engineered to be extremely durable, but if you suspect that it may have been damaged in some way, you can perform this quick and easy integrity test in the field. A clear widemouth bottle is required, but no special tools are needed.

    NEW: The MSR Guardian™ Purifier


    Nothing is safer or easier to use for purifying even the most challenging water sources than the Guardian purifier. Originally designed for military squads, it brings this advanced technology to global travelers, backcountry users, and those stocking emergency kits. Fast and easy to use, this pump purifier offers viral protection without chemicals, critical for travel in developing nations and popular wilderness areas. Its advanced hollow fiber media offers the most reliable way to purify even the filthiest water. Add its long-lasting and self-cleaning performance, and this may be the only treatment device you’ll ever need.

    Unanswered Question

    Dear Sir:

    I was looking at the MSR Guardian Filter. We typically filter from a one gallon jug to another one gallon jug.
    Thus a couple of questions.
    Can you attach an outlet hose making it easier to pump from one jug to another?
    Since the filter back flushes. I would guess we should only pump 3/4 gallon of water before getting a new supply for the jug. Thoughts?

    Holy crap, it is finally here! I cannot wait for someone to review the Guardian - so cool! We need pics and videos, let's see some pump races!