Skip to Content

An Honest MSR Guardian Gravity Water Purifier Review & Field Test

We take pride in providing authentic travel recommendations based on our own experiences through unique imagery and visiting each destination. We may earn a commission when you purchase a product or book a reservation. Learn more ›

Water. It’s quite important, isn’t it? We humans are made of around 55%-60% of the stuff, and we need to keep topping it up; otherwise, we’ll shrivel like a dried prune and expire unpleasantly.

If you’re lucky enough to live somewhere you have access to clean drinking water, achieving your daily recommended intake of H2O is fairly straightforward. Grab your favorite receptacle, turn on the tap, and voilà – a cool glass of Adam’s ale.

But what about when you’re traveling? What about if you live somewhere there isn’t any clean drinking water? Perhaps you’re camping for several days off the grid? Or maybe you’re in a region infamous for its waterborne diseases and other microscopic nasties?

Enter the MSR Guardian Gravity Water Purifier. With military-grade construction, this device promises to filter your water supply and make it clean and safe to drink. It guarantees to remove viruses and other contaminants for your peace of mind.

Whether you’re in the field, in a hotel room, or in an emergency, this could be the difference between survival and the opposite of survival. Or a quenched thirst and dehydration, at the very least.

The travel and adventure gods have smiled on me recently, and an MSR Guardian Purifier landed in my lap. As such, I thought I would do an unbiased review of this high-end water filter. From unboxing to testing on the beautiful Namakogan River in Northern Wisconsin, I will walk you through my experience.

Is it easy to use? Is it portable? Who is it for? And, most importantly, does it work? Let’s dive right into our MSR Guardian Gravity Water Purifier Review.

Who Is Mountain Safety Research?

Mountain Safety Research Logo

Mountain Safety Research, or MSR for short, is a legendary backpacking company established and headquartered in Seattle. Founded in 1969 by mountaineer Larry Penberthy, they have developed a reputation for designing super lightweight camping, hiking, and mountaineering equipment. I have one of their two-man hiking tents, and it’s outstanding.

Always innovating, MSR strives to push the boundaries of gear technology. With a focus on durable, safe, and reliable products, they have risen to be one of the best outdoor companies in the world. And while their stuff isn’t cheap, you get what you pay for in this game.

See Related: Best Van Camping Equipment [Essentials & Gadgets]

MSR Guardian Purifier Review

MSR Guardian Purifier set
MSR / Amazon

The Packaging of The MSR Guardian Gravity Purifier

Box of MSR Guardian Gravity Purifier
Stuart Jameson / ViaTravelers

Starting with my first impressions, the packaging of the MSR Guardian Gravity Purifier is solid and compact, with no unnecessary fluff. Written in English and French, the box provides all the essential details.

It includes what the product does (removes bacteria 99.9999%, protozoa 99.9%, and viruses 99.99%) and who it’s for (travelers, group outings, and emergency preparedness), and how it works (a graphic explains the whole process). And for eco-conscious people like me, the information that it has the potential to save up to 3,000 one-liter plastic water bottles is an enticing bonus. Chalk one up for the environment.

Unboxing the MSR Guardian Gravity Purifier

Unboxing MSR Guardian Gravity Purifier
Stuart Jameson / ViaTravelers

Opening the packaging, I notice a smart, sturdy carry bag with the MSR logo. It features an Oxford weave cloth prevalent in many quality outdoor products, offering a marriage of reassuring durability and style. With a DWR finish, the contents are protected from the elements and easy to pack and transport.

Inside, there’s a sewn-in instruction manual – a smart move to prevent losing it during your adventures. A more detailed manual is also included, including a full owner and operator guide.

First Look at the MSR Guardian Gravity Purifier

Complete set of MSR Guardian Gravity Purifier
Stuart Jameson / ViaTravelers

The Guardian Gravity Purifier is neatly rolled up in its carry bag. It feels lightweight but sturdy when picking it up and unraveling it for the first time.

The hardware feels quality – as you would expect from an MSR product. To a total noob, the dangling hoses and valves might initially look a little overwhelming. But once you learn how to use it, it holds no fear. And at just 18.7 ounces, it’s one of the lightest filters in its class.

See Related: Osprey Backpacks Review: Are They Worth It?

Using the MSR Guardian Gravity Purifier: A Kayaking Adventure

Portable MSR Guardian Gravity Purifier on a Kayak
Stuart Jameson / ViaTravelers

I had to test it out as part of my MSR Guardian Gravity Water Purifier Review. Is there a better way to test a product than out in the field? Or on the water, in this case.

Wife and adventure dog in tow, I took my inflatable kayak and MSR Gravity water purifier to the Namakogan River in Northern Wisconsin. It might not be comparable to somewhere like the Ganges in India, but it was ideal for our testing purposes.

I couldn’t wait to get out there and put the MSR Guardian through its paces. The procedure is simple enough:

  • Fill the 10-liter reservoir at your chosen water source, seal it like a roll-top dry bag, and hang it on a tree, coat hook, or anything appropriate. The optimal reservoir hang height is around six feet for the best possible flow rate.
  • Open the purge valve and purge air and water from the hose. Once bubbles are clear, you can close the purge hose clamp.
  • Attach your vessel to the universal bottle adapter (ideal for wide-mouth water bottles) and open the shutoff clamp. Clean, purified water devoid of unpleasant tastes and viruses is the result.

How Does the MSR Guardian Gravity Purifier Work?

How MSR Guardian Gravity Purifier Works
Stuart Jameson / ViaTravelers

I don’t profess to be some boffin on water filters. Heck, this was my first time using such a device. But I will tell you what I do know.

This two-stage purifier has passed the most rigorous scientific certification for water filtration. It uses activated carbon and hollow fiber technology to filter water, reduce chemicals, remove dirt, and protect you from waterborne viruses.

The pore size of the fiber membrane is so minute it traps even the tiniest of viruses, while the carbon component keeps chemicals, odors, and unpleasant tastes at bay.

It will turn murky water into crystal clear, life-giving aqua, which means you can worry about whether or not you left the gas on at home rather than potential polluting pathogens getting into your tum.

Where Can You Use the MSR Guardian Gravity Purifier?

Polluted water filled with different waste and garbage
overcrew / Adobe Stock

While I don’t recommend filling up at your nearest human waste outlet pump, there are plenty of places the MSR Guardian Purifier will come into its own. Feel free to dip it into lakes, ponds, rivers, and streams.

It will provide virus protection directly from a hotel’s suspicious tap water, places with poor sanitation, and popular campsites. It’s particularly useful in developing nations, where the spread of human viruses in water courses is a significant problem. Don’t clean your teeth without it.

Admittedly I was a little apprehensive at first, but after witnessing what the MSR Guardian Purifier could do, I wasn’t at all concerned that there might have been a bear pooping upriver. Or a drunk emptying his bladder into a mountain stream. Or a dead body floating…you get the idea.

How Long Does the MSR Guardian Gravity Purifier Last?

Trying Out MSR Guardian Gravity Purifier
Stuart Jameson / ViaTravelers

Alas, all water filters will need replacing eventually. My wife’s been on at me for so long to update the one in our fridge. It’s a wonder I’ve not developed a kidney stone.

Thankfully, the MSR Guardian Gravity filter life is an impressive 3,000 liters. That’s more than most typical campers, hikers, and holidaymakers will ever need.

That comes with a caveat, of course. You do need to take care of it, use it properly, and ensure it stays clean, well-maintained, and in peak condition. You’ll find everything you need to know in the accompanying instruction manual, including how to store, flush, and clean the system.

See Related: What to Bring on a Camping Trip with Friends

Who is the MSR Guardian Gravity Purifier For?

Crowded campsite near the summer lake
love1990 / Adobe Stock

I’ve been traveling solo for most of my globetrotting life, so having a 10-liter gravity filter bag might not necessarily be for me. Having said that, I did spend several months in countries where the water quality was questionable (to say the least).

It might have saved me a small fortune on bottled water, not to mention the sheer amount of plastic waste. Hindsight is a wonderful thing, and also extremely useless.

For family and group trips, long-term campers, and anyone experiencing challenging wilderness water sources, this can be an essential piece of kit. If you’re in a region that suffers natural disasters, you will find this invaluable if your regular water source is compromised.

But it can be for anyone who intends to stay for an extended period anywhere the water isn’t safe to drink. It might well be the first thing you pack for your next backpacking trip.

MSR Gravity Purifier Pros and Cons

Drinking the MSR Guardian Gravity Purifier filtered water
Stuart Jameson / ViaTravelers

So, while there are obvious benefits to using the MSR Gravity Purifier, it isn’t all sunshine and lollipops. And this being a fair, considered review, here’s a list of pros and cons:


Pro: Military Grade Construction

As the only gravity water purifier with the stamp of approval from the US military, the MSR Guardian Gravity Purifier is undoubtedly worth owning – at least for those who will get the most out of it.

Pro: Highly Portable and User-Friendly

Lightweight, top-quality, and easy to use, it has been built to last and get the job done.

Pro: It Gets Results

I was impressed at the clarity and taste of the water it filtered, especially considering how filthy it was when I first bagged it. You’ll get a kick out of creating delicious, free water from an almost unlimited source. Take that Nestlé/Coca-Cola/Danone…

Pro: State-of-the-Art Technology

The fact that the MSR Guaridan Purifier genuinely does what it’s supposed to do is the selling point. This is a state-of-the-art water filtration system that doesn’t have an equal in the gravity filters market.

Since its release, it has become one of the best portable water filters available. Dirty water goes in, and clean water comes out. Don’t you just love it when things work?


Con: Slow Flow Rate

I felt the flow rate was a little on the slow side, but admittedly I have not tested it against the next leading gravity purifier or similar comparable product. Flow rates vary between most filters, but if you’re not in a rush to purify water, this works perfectly fine. Then again, as a gravity purifier, perhaps I didn’t hang it high enough.

Con: Hoses Galore

I also found it a bit of a fiddle to organize the hoses to prevent them from trailing on the floor (and from garroting myself). But practice breeds familiarity, and I won’t look like such a rookie next time this gets an outing.

Con: Cleaning and Maintenance is a Chore

And while it’s easy to pack up, there is a full-on cleaning regimen required if it’s going to be in storage longer than 15 days. This might cause a bit of a headache for some, but it’s par for the course with any portable water purification system.

Con: Eye-watering Price Tag

Perhaps the most significant downside is the price point. The MSR Guardian Purifier won’t give you much change from $300 (it won’t change from $300 after tax). But this kind of technology is at the high end of water purifiers, and it doesn’t come cheap.

You could wait for a sale, or look for other ways to save money on the purifier. If you’re an REI Co-op Member and buy the MSR Guardian Purifier from REI, you’ll receive an estimated $30 back as part of your annual member reward.

My Final Thoughts on the MSR Guardian Gravity Purifier

An Honest MSR Guardian Gravity Water Purifier Review & Field Test

Planning to purchase MSR Guardian Gravity Water Purifier? Here's a comprehensive MSR Guardian Gravity Water Purifier review for you.

Product Brand: MSR Guardian Gravity Purifier

Editor's Rating:


  • Military Grade Construction Highly Portable and User-Friendly It Gets Results
  • State-of-the-Art Technology


  • Slow Flow Rate
  • Hoses Galore
  • Cleaning and Maintenance is a Chore Eye-watering Price Tag
Hanging MSR Guardian Gravity Purifier to filter the water
Stuart Jameson / ViaTravelers

I had a blast trying out the MSR Guardian Gravity Water Purifier. The cynical skeptic in me had doubts, but when the purge hose flushes out that filth and you see crystal-clear water pouring into your bottle, it’s a testament to what science can achieve. But the ultimate question remains. Is the MSR Guardian Gravity Water Purifier worth it?

Yes and no. For casual campers and travelers who don’t get away that often, there’s a touch of overkill here. On the other hand, if you know you’ll get a lot of use out of this, then it’s well worth the investment. And as a survival water purifier, it’s one of the best in the business. You can’t put a price on health, anyway.

Travel-friendly, the compact system fits easily into your backpack or carry-on luggage, ensuring you can take it anywhere. And at the end of the day, anything that limits the amount of bottled water we buy will get a thumbs up from me. Now, if they could only make one that turns water into beer, I’d be a very happy camper.

More information about the MSR Guardian Gravity Purifier can be found here.

Related Resources

Leave a comment

Your email address will not be published. Required fields are marked *

    ↑ Top