MSR - Guardian Purifier
Having clean drinking water is critical when you're on backcountry adventures. Originally designed for the military, the Guardian water purifier removes bacteria, viruses and many other impurities so you can stay hydrated without worry. Patent-pending self-cleaning system cleans with each stroke; no need to backflush or clean filter. Rugged design stands up to heavy use and extreme environments. Purifies 2.5 liters per minute from nearly any water source and treats up to 10,000 liters. The only hollow fiber purifier on the market that can withstand freezing temperatures. Drop tested from 6' onto concrete. Meets NSF protocol P248, the testing standard used by the U.S. military for removing viruses. Also removes protozoa, bacteria and sediment. Made in the USA, components USA and imported.
Having clean drinking water is critical when you're on backcountry adventures. Originally designed for the military, the Guardian water purifier removes bacteria, viruses and many other impurities so you can stay hydrated without worry. Patent-pending self-cleaning system cleans with each stroke; no need to backflush or clean filter. Rugged design stands up to heavy use and extreme environments. Purifies 2.5 liters per minute from nearly any water source and treats up to 10,000 liters. The only hollow fiber purifier on the market that can withstand freezing temperatures. Drop tested from 6' onto concrete. Meets NSF protocol P248, the testing standard used by the U.S. military for removing viruses. Also removes protozoa, bacteria and sediment. Made in the USA, components USA and imported.
Having clean drinking water is critical when you're on backcountry adventures. Originally designed for the military, the Guardian water purifier removes bacteria, viruses and many other impurities so you can stay hydrated without worry. Patent-pending self-cleaning system cleans with each stroke; no need to backflush or clean filter. Rugged design stands up to heavy use and extreme environments. Purifies 2.5 liters per minute from nearly any water source and treats up to 10,000 liters. The only hollow fiber purifier on the market that can withstand freezing temperatures. Drop tested from 6' onto concrete. Meets NSF protocol P248, the testing standard used by the U.S. military for removing viruses. Also removes protozoa, bacteria and sediment. Made in the USA, components USA and imported.
Having clean drinking water is critical when you're on backcountry adventures. Originally designed for the military, the Guardian water purifier removes bacteria, viruses and many other impurities so you can stay hydrated without worry. Patent-pending self-cleaning system cleans with each stroke; no need to backflush or clean filter. Rugged design stands up to heavy use and extreme environments. Purifies 2.5 liters per minute from nearly any water source and treats up to 10,000 liters. The only hollow fiber purifier on the market that can withstand freezing temperatures. Drop tested from 6' onto concrete. Meets NSF protocol P248, the testing standard used by the U.S. military for removing viruses. Also removes protozoa, bacteria and sediment. Made in the USA, components USA and imported.
in 6 offers
The lowest price for MSR - Guardian Purifier right now is $549.00 at Snowys Outdoors, compared across 6 retailers.
The all-time low was $399.00 on 30 Sept 2025 — today's price is 38% above the lowest ever. It has been notably cheaper before — worth setting a price alert.
Prices last updated 10 June 2026.
Last updated at 10/06/2026 13:22:17
MSR Guardian Pump Water Purifier
Free delivery
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Guardian Water Purifier
Free 60-day returns
MSR Guardian Purifier - Outback Equipment Australia - Camping Gear & Accessories
Delivery between 15–17 June $21.56
MSR Guardian Portable Water Purifier
MSR Guardian Purifier
Free delivery between Fri – Mon
MSR GUARDIAN WATER PURIFIER
Free delivery between Mon – Tue
originally posted on cascadedesigns.com
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.
originally posted on moosejaw.com
I ordered this so our Trail Life boys and dads would have clean water to drink on a 4 day/3 night canoe adventure on the Green River. The Green River is called the Green River because it's green. Very inventive, I know. And if you choose to dip your noggin' in the water of the Green River and open your eyes, you will not see more than 4 or 5 inches. It's green. It's nasty. I choose not to think about it.This pump was our answer to getting clean water to drink for these 4 days. It arrived (and BTW, MooseJaw worked with me to update the shipping address to our base camp so we'd have it in time). We took the pump out of the box, dropped it in the water and started pumping. Pet Rocks are the only thing I can think of that has easier Quick-Start steps.I love the ... MoreI ordered this so our Trail Life boys and dads would have clean water to drink on a 4 day/3 night canoe adventure on the Green River. The Green River is called the Green River because it's green. Very inventive, I know. And if you choose to dip your noggin' in the water of the Green River and open your eyes, you will not see more than 4 or 5 inches. It's green. It's nasty. I choose not to think about it.This pump was our answer to getting clean water to drink for these 4 days. It arrived (and BTW, MooseJaw worked with me to update the shipping address to our base camp so we'd have it in time). We took the pump out of the box, dropped it in the water and started pumping. Pet Rocks are the only thing I can think of that has easier Quick-Start steps.I love the design of the flat foam pad that forces the intake pre-filter to stay under the surface of the water. AND I also really appreciate the 'flush' tube running along side of the in-take tube. This really is an ingenious piece of engineering.
originally posted on REI
Don't bother. I splurged on this because I'm a germaphobe and wanted peace of mind. I saw the negative reviews about various points of plastic failure/leaks, but after further research decided it was user error and figured I'd be extra careful. Tested it out in my kitchen last week just before a trip, being wayyy more gingerly than you should have to be with a $400 product designed for hiking, but whatever. Even then, within a few pumps it began leaking from the top, and "dirty" intake water ran down the sides all over my container (& counter). Ended up having to do a last minute run to REI to return & replace it before a trip. Thank God I tested it before needing to rely on it when miles from any road. If it worked, it would be worth the money, and even worth a ... MoreDon't bother. I splurged on this because I'm a germaphobe and wanted peace of mind. I saw the negative reviews about various points of plastic failure/leaks, but after further research decided it was user error and figured I'd be extra careful. Tested it out in my kitchen last week just before a trip, being wayyy more gingerly than you should have to be with a $400 product designed for hiking, but whatever. Even then, within a few pumps it began leaking from the top, and "dirty" intake water ran down the sides all over my container (& counter). Ended up having to do a last minute run to REI to return & replace it before a trip. Thank God I tested it before needing to rely on it when miles from any road. If it worked, it would be worth the money, and even worth a little careful handling. Maybe the filter is great! Trouble is the plastic that houses it is cheaper than a toy. Got a sawyer squeeze for literally less than a tenth of the price, and some chlorine drops for peace of mind. Should have done that from the beginning.
| Is discontinued by manufacturer | No |
| Capacity | 2.5 Liters, 10 Liters |
| Included Components | Water Purifier |
| Purification method | Hollow Fiber Membrane |
| Maximum flow rate | 2.5 Liters Per Minute |
MSR Guardian Pump Water Purifier
Free delivery
Affiliate Disclosure: We may receive a small commission for purchases made through this link at no extra cost to you. This helps support our site. Thank you!
Guardian Water Purifier
Free 60-day returns
MSR Guardian Purifier - Outback Equipment Australia - Camping Gear & Accessories
Delivery between 15–17 June $21.56
MSR Guardian Portable Water Purifier
MSR Guardian Purifier
Free delivery between Fri – Mon
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.
I ordered this so our Trail Life boys and dads would have clean water to drink on a 4 day/3 night canoe adventure on the Green River. The Green River is called the Green River because it's green. Very inventive, I know. And if you choose to dip your noggin' in the water of the Green River and open your eyes, you will not see more than 4 or 5 inches. It's green. It's nasty. I choose not to think about it.This pump was our answer to getting clean water to drink for these 4 days. It arrived (and BTW, MooseJaw worked with me to update the shipping address to our base camp so we'd have it in time). We took the pump out of the box, dropped it in the water and started pumping. Pet Rocks are the only thing I can think of that has easier Quick-Start steps.I love the ... MoreI ordered this so our Trail Life boys and dads would have clean water to drink on a 4 day/3 night canoe adventure on the Green River. The Green River is called the Green River because it's green. Very inventive, I know. And if you choose to dip your noggin' in the water of the Green River and open your eyes, you will not see more than 4 or 5 inches. It's green. It's nasty. I choose not to think about it.This pump was our answer to getting clean water to drink for these 4 days. It arrived (and BTW, MooseJaw worked with me to update the shipping address to our base camp so we'd have it in time). We took the pump out of the box, dropped it in the water and started pumping. Pet Rocks are the only thing I can think of that has easier Quick-Start steps.I love the design of the flat foam pad that forces the intake pre-filter to stay under the surface of the water. AND I also really appreciate the 'flush' tube running along side of the in-take tube. This really is an ingenious piece of engineering.
Don't bother. I splurged on this because I'm a germaphobe and wanted peace of mind. I saw the negative reviews about various points of plastic failure/leaks, but after further research decided it was user error and figured I'd be extra careful. Tested it out in my kitchen last week just before a trip, being wayyy more gingerly than you should have to be with a $400 product designed for hiking, but whatever. Even then, within a few pumps it began leaking from the top, and "dirty" intake water ran down the sides all over my container (& counter). Ended up having to do a last minute run to REI to return & replace it before a trip. Thank God I tested it before needing to rely on it when miles from any road. If it worked, it would be worth the money, and even worth a ... MoreDon't bother. I splurged on this because I'm a germaphobe and wanted peace of mind. I saw the negative reviews about various points of plastic failure/leaks, but after further research decided it was user error and figured I'd be extra careful. Tested it out in my kitchen last week just before a trip, being wayyy more gingerly than you should have to be with a $400 product designed for hiking, but whatever. Even then, within a few pumps it began leaking from the top, and "dirty" intake water ran down the sides all over my container (& counter). Ended up having to do a last minute run to REI to return & replace it before a trip. Thank God I tested it before needing to rely on it when miles from any road. If it worked, it would be worth the money, and even worth a little careful handling. Maybe the filter is great! Trouble is the plastic that houses it is cheaper than a toy. Got a sawyer squeeze for literally less than a tenth of the price, and some chlorine drops for peace of mind. Should have done that from the beginning.
This is by far one of my fave pieces of gear!I love taking this on backcountry trips as it eliminates the need to carry water.The Guardian attaches directly to a wide mouth Nalgene bottle, some Gregory bladders and MSR water storage bags making it super convenient.It’s fairly durable and easy to maintain.Also, MSR offers great customer service where they ship parts cheap, offer directions on how to maintain the device and how to test whether it still seals well.The only downside is that it is bulky and on a heavier side, however, on longer trips this isn’t an issue since it saves me from carrying water and it pumps very efficiently.I have a different filter for day hiking but the Guardian will always be my special guy.
I just received the Gaurdian in prep for this year's hiking adventures. I've been impressed with all of the online reviews. The price was higher than I thought it should be, but after months of internal debat I decided I was willing to pay for a premium safe and reliable solution. I've been impressed with it so far out of the box.I use an integrated water bladder bag in my backpack with a drinking tube. The tube has simple press/snap disconnects. I would like to connect a hose from the output of the Gaurdian to the place where my drinking tube connects. This would allow me to filter water directly into the bladder inside the pack without unpacking (rather than a bulky water bottle). I had thought this would be a common use-case, but after spending considerable time ... MoreI just received the Gaurdian in prep for this year's hiking adventures. I've been impressed with all of the online reviews. The price was higher than I thought it should be, but after months of internal debat I decided I was willing to pay for a premium safe and reliable solution. I've been impressed with it so far out of the box.I use an integrated water bladder bag in my backpack with a drinking tube. The tube has simple press/snap disconnects. I would like to connect a hose from the output of the Gaurdian to the place where my drinking tube connects. This would allow me to filter water directly into the bladder inside the pack without unpacking (rather than a bulky water bottle). I had thought this would be a common use-case, but after spending considerable time searching I haven't found readily available solutions / products.Two questions:1. Does MSR make an adapter hose?2. Would adding a hose like this to the output and pushing water directly into a bladder do anything to impact water safety?In the interrim I've purchased some bulk hoses and connectors and will attempt to build something
This filter probably saved my life. I was in an area too far from Cell service. I was hiking with a buddy and was suddenly nauseous. I could barely stand. We were 10 miles downhill or five uphill to service. I do carry an inreach for emergencies and almost had to hit the SOS button. We had gone through 10 liters of water so far that day hiking the mountains of the Sonoran desert and were very low. Due to my illness we had been out in the sun longer than expected making everything worse.We found a mud puddle and he dropped this hose in and started to suck up clear water. I was astonished. I ended up drinking this muddy tasting but safe water as I rehydrated under a tree. I vomited several more times but would not have been able to without that safe water in my body. ... MoreThis filter probably saved my life. I was in an area too far from Cell service. I was hiking with a buddy and was suddenly nauseous. I could barely stand. We were 10 miles downhill or five uphill to service. I do carry an inreach for emergencies and almost had to hit the SOS button. We had gone through 10 liters of water so far that day hiking the mountains of the Sonoran desert and were very low. Due to my illness we had been out in the sun longer than expected making everything worse.We found a mud puddle and he dropped this hose in and started to suck up clear water. I was astonished. I ended up drinking this muddy tasting but safe water as I rehydrated under a tree. I vomited several more times but would not have been able to without that safe water in my body. We finally made it to the top just as it got dark. I bought this two days later once I could sit up again.He said his is several years old. I've always done Chem drops but this is worth the extra pack space. You can't Chem drop mud.
I am blown away with how great this pump is! I purchased it over a year ago and have used it on around ten backpacking trips. I love that I can quickly get reliably safe water in seconds. Well, around a minute to take out of the pouch and screw on the Nalgene, then less than 60 seconds to filter. I've taken it on late fall trips when we encountered freezing temps, and I didn't have to worry about ruining the filter. It's heavier than most other filters, but is only just over a pound. But before this filter, I used to carry an additional liter in my pack. With this filter, knowing that I can filter water from any source, I've actually saved almost a pound from my pack! It is so easy and quick to filter water, I've stopped for a break near a stream, emptied my warm ... MoreI am blown away with how great this pump is! I purchased it over a year ago and have used it on around ten backpacking trips. I love that I can quickly get reliably safe water in seconds. Well, around a minute to take out of the pouch and screw on the Nalgene, then less than 60 seconds to filter. I've taken it on late fall trips when we encountered freezing temps, and I didn't have to worry about ruining the filter. It's heavier than most other filters, but is only just over a pound. But before this filter, I used to carry an additional liter in my pack. With this filter, knowing that I can filter water from any source, I've actually saved almost a pound from my pack! It is so easy and quick to filter water, I've stopped for a break near a stream, emptied my warm water bottles, and in just a couple of minutes, filtered nice, cold water into my bottles! Got three minutes, filter a fresh bottle. The gravity filters work ok, but they can be difficult to fill from a shallow stream. I can easily use the Guardian in an inch or two of water. As long as the white part of the intake is around 1/2 submerged, it will work. Also, the take lines are long enough that you can use it while standing over the water source. I was impressed with how clear it filtered water from a tannin-rich pond in the Whites. A friend set up his gravity filter. You could see the difference between the tea-colored pond water in the top bag and the light tan filtered water in the lower bag. But my Guardian-filtered water was perfectly clear! I wish I took a photo, as the difference was striking! Before purchasing the Guardian, I read the negative reviews about the "over tightening" issue. A couple of the better reviews said that loosening the over-tightened seam stopped the leak. Before using mine, I drew a line with a sharpie across the guilty seam (the one about two inches up from the bottom). That way, I will see if I start to change the tightness of the seam, and if I ever over-tighten, I can easily realign it. Also, I screw my Nalgene bottle on only enough to be barely snug. You don't have to make it tight. The bottle won't fall off when you're pumping. It's pricey, but with a 10,000 liter lifespan, should outlast the cheaper filters many times over.
Both a fellow camping friend and I have this same model. Initially it worked very well. Well thought out, fits nicely in its case, which had a mesh side that could dry out, etc.Then noticed a couple of issues. Firstly the lever is connected to a body via a plastic type of nut and bolt, one day in the bush, that just fell out. Fortunately I found that and put back in (and in a pinch one could improvise with something small), but still - didnt hold up very well. Emailed Customer Service, NO RESPONSE.The larger issue came this year - the inside top of my filters are melted together and are rock hard by about 2 cm. I does not work. So we returned back home for my friend to get his Guardian - same thing. We cant figure out what when wrong with them. I have had mine for ... MoreBoth a fellow camping friend and I have this same model. Initially it worked very well. Well thought out, fits nicely in its case, which had a mesh side that could dry out, etc.Then noticed a couple of issues. Firstly the lever is connected to a body via a plastic type of nut and bolt, one day in the bush, that just fell out. Fortunately I found that and put back in (and in a pinch one could improvise with something small), but still - didnt hold up very well. Emailed Customer Service, NO RESPONSE.The larger issue came this year - the inside top of my filters are melted together and are rock hard by about 2 cm. I does not work. So we returned back home for my friend to get his Guardian - same thing. We cant figure out what when wrong with them. I have had mine for about 12 months and my friends for about 25 months, and neither of us have seen this before.So we assume there is an explanation and a possible fix for this, but again CUSTOMER SERVICE - NO RESPONSE.I have emailed them 2 times (3rd time last night)DISAPPOINTING. ESPECIALLY FOR SAFETY GEAR.
Worth it. I previously bought Lifestraws, a Lifestraw gravity bag (which was a complete failure), Grayl purifiers (awesome but cumbersome), and even used someone else's Katadyn pump filter. The Guardian purifier is the right way to go. I want to enjoy my trip (it needs to be easy to use and fast), I want to be safe (don't want to stress about bacteria or viruses), and I don't want to have to hassle with equipment (don't want to do a bunch of cleaning). This purifier (better than a "filter"!) is amazing. It's the easiest thing I've used, its worry-free on water quality, and it doesnt have any storage cleaning requirements. I should learn my lesson. Every time I try to go the cheaper route, I just wind up eventually buying the expensive thing and wishing I had started ... MoreWorth it. I previously bought Lifestraws, a Lifestraw gravity bag (which was a complete failure), Grayl purifiers (awesome but cumbersome), and even used someone else's Katadyn pump filter. The Guardian purifier is the right way to go. I want to enjoy my trip (it needs to be easy to use and fast), I want to be safe (don't want to stress about bacteria or viruses), and I don't want to have to hassle with equipment (don't want to do a bunch of cleaning). This purifier (better than a "filter"!) is amazing. It's the easiest thing I've used, its worry-free on water quality, and it doesnt have any storage cleaning requirements. I should learn my lesson. Every time I try to go the cheaper route, I just wind up eventually buying the expensive thing and wishing I had started there.The *only* complaint I have is that the little floater thing seems to be design to float on the water and have the water sucker thing dangle under water. That doesn't really work. I ended up have to pin the line down with a rock to keep the water sucker where I wanted it.
I have had this filter for going on 3 years and have used it on several 5 day trips with groups of 5-6 in the upper midwest. Filtering conditions have often been difficult with high tannin levels and significant silty runoff after storms. It has performed extremely well and its quite fast. The self-cleaning feature is excellent. If you read the reviews on this filter, 80-90% say it's awesome and about 10% say it's horrible because they've had a major failure. It obviously would stink to pay $350 for a filter and then have it fail in the field. There are some plastic pieces which have the potential either to fail or pop off. I have not had issues with the "over tightening" issue despite the best efforts of my boy scouts. I have found this filter much easier to ... MoreI have had this filter for going on 3 years and have used it on several 5 day trips with groups of 5-6 in the upper midwest. Filtering conditions have often been difficult with high tannin levels and significant silty runoff after storms. It has performed extremely well and its quite fast. The self-cleaning feature is excellent. If you read the reviews on this filter, 80-90% say it's awesome and about 10% say it's horrible because they've had a major failure. It obviously would stink to pay $350 for a filter and then have it fail in the field. There are some plastic pieces which have the potential either to fail or pop off. I have not had issues with the "over tightening" issue despite the best efforts of my boy scouts. I have found this filter much easier to maintain than the gravity filters, which seem to require a fair amount of babying in my usual filtering conditions. My biggest complaint of this filter is that the weighting of the float makes it such that it often flips over and sucks 50% air, so you need to pin it down with a rock for it to work properly. Overall, based on my experience, this is probably the best filter on the market in large part because of the self cleaning feature. There is a low, but finite chance for a fail, but it suggests that no matter how much one pays for a filter, one should probably bring a back up method of water treatment especially for a longer trip. It's particularly suited for larger groups who will get many uses out of it to defray the high initial cost.
| Is discontinued by manufacturer | No |
| Capacity | 2.5 Liters, 10 Liters |
| Included Components | Water Purifier |
| Purification method | Hollow Fiber Membrane |
| Maximum flow rate | 2.5 Liters Per Minute |
