We’ve read the reviews across the web for the MSR Guardian Purifier System and summarize the results below:
Universal Ranking
PeakScore: 88 (out of 100)
User Rating: 4.4 stars 
Expert Rating: 4.4 stars
Number of Ratings Reviewed: 122
Pros & Cons
Reasons to buy:
User Reviews
- Able to work in a variety of conditions.
- Able to use the pump to get water from small puddles, where the filter can’t be fully submerged, allowing for versatility.
- 10% of the water exits for self-cleaning.
- Zippered cloth storage case for secure and easy transport.
- The pump handle can close over the hose end, holding the tube in place and keeping the apparatus compact.
- Sturdy and durable material and build.
- Any part that seems susceptible to wear-and-tear can be replaced if needed.
- Very user-friendly and long-lasting.
Expert Reviews
- Able to filter a full Nalgene bottle in under 30 seconds.
- Integrated back-flush, meaning the apparatus cleans itself as it pumps water, saving time and energy.
- Purifier uses 10% of the clean water to flush any contaminants back out.
- Pushes water through the .02 filter to remove both bacteria and viruses more efficiently than numerous other filters.
- Features a lifespan of over 10,000 liters.
- Able to withstand freezing temperatures.
- Features the longest lifespan of filters that also remove viruses.
- Built to withstand being frozen or being dropped from 6 feet.
- Able to withstand crush-testing of 300 pounds.
- One of the “best overall backpacking water filters”.
Reasons NOT to buy:
User Reviews
- Some reports of the filter dying after only minimal use due to using “dirty” water.
- The requirement of pumping the water into a Nalgene bottle is tedious, and can add heavier weight to the apparatus, in comparison to using water bags.
- Some reports of a catastrophic failure of the filter after only minimal use a few days into a trip.
Expert Reviews
- Expensive option, despite having many features to make it worth the money.
- Doesn’t remove chemicals or odors.
- Heavy and bulky.
- Hand pumping can be somewhat tedious and time consuming.
Summary:
The MSR Guardian Purifier System is heavy and expensive, but with good reason. The pump gets rid of bacteria and viruses within the water, cleans itself with the 10% back-flush mechanism, filters quickly and efficiently, and is extremely durable, withstanding freezing temperatures and being dropped or crushed. The numerous features and technical specifications that comprise this system can make it worth the price and weight, especially considering this product has the longest lifespan of any virus-removing filter system.
Multimedia:
Note: User and expert rankings were reviewed across the web. Some expert reviews include these: 1, 2, 3, 4, 5, 6, 7, 8, 9.