MSR Guardian Gravity Purifier 80+ Day Review

TLDR: A water filter that not only provides some of the best filtration on the market (even protecting from viruses), it works incredibly well and is simple to set up, purge, filter many litres of water, and pack down. A reliable water filter for groups to use at camps.

The claim on the label

When you go looking for a new piece of kit often the only information available is what the manufacturer, or retailer, supplies. As we spend a fair amount canoeing along waterways, having a way to treat water wherever we are camping means we don't have to try and carry all the fresh water we are going to need. There are many different ways of making water safe however, we made our decision to get our Guardian Gravity Purifier based on this information.

Manufacturer: MSR

Product full name: Guardian Gravity Purifier

Price tag (at time of purchase): £198 (January 2023)

Retailer: Trekitt (https://www.trekitt.co.uk/)

Key claims or standout information:

• The purifier meets NSF Protocol P248 (the U.S. military standard), confirming its ability to remove viruses, bacteria, protozoa, and sediment. This viral protection is the standout benefit, as most standard backpacking filters are not capable of this.

• The two-stage purifier includes activated carbon to reduce chemicals and unpleasant tastes and odors.

• There is a 10 liter bag style reservoir that is easy to fill at sinks and streams alike. 

• Simply opening the purge hose flushes the system to clean it and maintain flow rate. No complicated back flushing is required.

• A filtration rate of up to one liter in two minutes, when used at an optimal reservoir hang height of 1.8 m (6 feet).

• Attaches to the same thread used on Nalgene bottles, and MSR Dromedary Bags.

• Weight 0.53 kg (1 lb 2 oz)

• Filter cartridge life of 3,000+ liters

• Filter integrity checks can be conducted in the field.

Out on the trail

We all know that manufacturers’ and retail staff's claims are all well and good, but the real proof is in the use on the trail. We try to give you an understanding of how much we have used the equipment and critically, in what conditions, before we cast judgement on its performance. 

Estimated time of use so far: 80+ days of use (usually our only drinking water source for those days too)

Adventure we have used this on: NFCT, Great Glen, and Timber Rafting Klarälven in particular.

What we have used it for: When adventuring in groups of four or more we’ve ended up using this for filtering water for drinking, cooking, and washing.

How has it performed: This water filter has worked fantastically. It did take a few attempts to get the knack of filling the bag with a good amount of water, but once you have that knack then getting 8+ Liters of water becomes easy. Even when using water from the silty Klarälven River the self cleaning purge feature worked well, keeping the flow rate up. The only failure we have had was about 40 days into our NFCT trip, where the pipe by the cap developed a few splits. This was resolved by cutting about 2.5 cm (1”) off and refitting the cap. Interestingly, we have not seen any further degradation after that. 

One small thing to bear in mind is that you ideally need to get the dirty water bag hanging from a height of around 1.8 m (6 feet). It can be a bit of a challenge lifting 10kg (22lb) above your head and getting the clips to align after 12 hours of paddling. We have found that this is significantly easier for the taller amongst our adventuring friends. However, this did not stop Katrina at one point rigging up a rather elaborate system of paracord and karabiners to hoist the bag up to the appropriate height without assistance.

Any modifications made: None at all. Something that we see as a safety piece of equipment (because not having clean water could cause all sorts of undesirable issues), we have been hesitant to make any alterations to, so no alterations have been made to this at all.

The Good The Bad and The Packable

Being realistic there is no perfect piece of equipment, there are always pros and cons, and so we try to give you our balanced view of what we feel about it and answer the question: does it make the packing list for our next adventure?

The bits we liked: The simplicity of the use of this purifier has to be the stand out benefit. It is quick to deploy, you can leave it to filter unattended without concern, and it is easy to pack away. No hassle, no complications. The integrity check is simple and easy to do, either at home, or out on the trail as well. 

How it could be better: This is only a very minor point, but it would be good if the detachable hanging point was a colour not found in nature. If it was a bright colour then it may have helped our adventure team from losing one while on the NFCT (a bright piece of paracord solved the proceeding attachment problem and the colour issue, so not too bad of an outcome).

There is one downside to this type of filter, and that is that it does take some time to filter and you have to have the dirty water bag higher than the clean water receptacle. This means that it is not great for on-the-go water filtration. For this reason whenever we take the MSR Guardian Gravity Purifier we often also take our MSR Guardian Purifier (the hand-pump style one) as we can then easily top up our water supplies through the day if needed.

What we think it is best suited for: Adventures where you don't want to have to treat your water with purification tablets, and you are purifying water for groups of four or more people at camp. 

Are we going to pack it for our next adventure?: If we are on an adventure with a group of four or more people where we need to filter water, then yes.

Does it get our seal of approval?

This purifier not only provides some of the best filtration on the market, it works incredibly well, it is simple to set up, purge, filter many litres of water, and pack down. It is a resounding yes from us.