Loading...

Guardian Purifier

The world’s most advanced backcountry purifier.

Nothing is safer or easier to use for purifying the most demanding backcountry water sources than the Guardian purifier. Originally designed for military squads, it brings this highly advanced technology to global travelers, backcountry users, and those stocking emergency kits. Fast and easy to use, this pump purifier offers the added viral protection you need when traveling in developing nations and popular wilderness areas. Its advanced hollow fiber filter offers the most reliable way to purify even filthy water conditions. Add its long-lasting performance and revolutionary self-cleaning ease, and this may be the only treatment device you’ll ever need.

$349.95
In stock
Find Online Find a Store

Behind the Scenes: MSR Water Research Lab

Nothing is safer or easier to use for purifying the most demanding backcountry water sources than the Guardian purifier. Originally designed for military squads, it brings this highly advanced technology to global travelers, backcountry users, and those stocking emergency kits. Fast and easy to use, this pump purifier offers the added viral protection you need when traveling in developing nations and popular wilderness areas. Its advanced hollow fiber filter offers the most reliable way to purify even filthy water conditions. Add its long-lasting performance and revolutionary self-cleaning ease, and this may be the only treatment device you’ll ever need.
  • Ultimate Protection: Meets NSF protocol P248, testing standard used by U.S. military, for removal of viruses, bacteria, protozoa, and sediment from “worst-case” water conditions.
  • Fast & Easy: Pumps a rapid 2.5 liters per minute, offering added viral protection without the need for chemicals, bulbs, batteries, or waiting.
  • Self-Cleaning: Pump self-cleans on every stroke, providing consistently fast flow rates with zero hassle—no backflushing or filter-scrubbing ever required.
  • Long-Lasting: Leading-edge hollow fiber cartridge treats up to 10,000+ liters.
  • Extremely Durable: Engineered to withstand heavy use, freezing, drops*, and harsh environments.

    *Withstands MSR water lab drop testing: 6 ft. to concrete.
Made in the U.S.A. of U.S. and Imported Materials
Size No
Color Smoke
Style No
Weight (Standard) 1 lbs 1.3 oz
Color Family Gray
Weight (Metric) 0.49 kg
Effective against bacteria Yes
Effective against chemicals/toxins No
UPC Code 040818023709
Effective against particulate Yes
Effective against protozoa Yes
Effective against viruses Yes
Filter media Advanced Hollow Fiber
Filter pore size (microns) 0.02
Flow (L/min) 2.5 liters per min
Cartridge life 10,000+ liters
Field cleanable Self-Cleaning
Field maintainable Yes
Water Bottle Adapter Yes
Cartridge replacement indicator Yes
Country of Origin Made in the U.S.A. of U.S. and Imported Materials

Documents and Instructions

Virtually all surface waters are contaminated with at least one of the three types of potentially disease-causing microorganisms: protozoa, bacteria, and viruses. A 1992 study found that 97% of U.S. rivers and lakes contain one or both of the protozoan parasites Giardia and cryptosporidia.
While it is true that you can drink directly from many water sources, it is critical to understand that each time you do, there is a chance of ingesting one of these bugs. Infection symptoms can range from an upset stomach to debilitating illness and, depending on where you are, can mean anything from a simple inconvenience to a life-threatening situation. Since microorganisms are impossible to see, taking the proper precautions with any water can help to ensure a safe trip.
Protozoa are the largest of the waterborne bugs measuring in the one-micron range. Giardia and cryptosporidia are the most infamous of the group. The infective cysts and oocysts of protozoa are extremely robust and can survive for months in a water source. They thrive in domestic and wild animals as well as humans. Cryptosporidia oocysts are known for their resistance to chemical treatment. Most disinfectants are ineffective, and the few that are require long dwell times to do the job.
Bacteria are an order of magnitude smaller than protozoa measuring in the 0.5 - 2 micron range. The most well-known bacteria are E. coli; others include Leptospira (which causes Leptospirosis), Campylobacter, Salmonella, and Shigella. Bacteria aren't as hearty, surviving in water only for weeks instead of months. However, unlike protozoa and viruses, which require a host to multiply, some bacteria can grow in water and so can be found in higher numbers than protozoa and viruses. Bacteria, like protozoa, are often carried by both animals and humans. Because of this, many water sources are contaminated with bacteria. Beware especially of sources near agricultural operations.
Viruses are the smallest type of pathogen, ranging between 0.02 - 0.3 microns. Waterborne viruses are very resilient and can survive for months. It is important to note that viruses are generally species-specific. In other words, those that infect animals do not infect humans and vice versa. Because of this, and the well-maintained sewage systems in developed countries, not as many water sources are contaminated with human viruses. However, in heavily traveled backcountry areas, viruses can be present where human waste is not disposed of properly. In developing countries with little or no sewage control, viruses are often widespread and purification in such countries should be standard procedure for all travelers.
First, it will usually take more than one organism to make you sick—around 10 for protozoa and viruses and 10 to 1,000,000 for bacteria depending on the species. The onset of symptoms can start anywhere from 10 hours to several weeks from the point of infection depending on the type and amount ingested, and constitution of the individual. Symptoms can range from nothing to diarrhea, abdominal cramps and pain, nausea, vomiting, muscle cramps, fever, fatigue, headache, chills, loss of appetite, and, in the case of hepatitis, dark urine and jaundice. Symptoms usually dissipate in a couple of days or weeks, again depending on the three elements above. Healthy adults will generally knock the illness without needing medical attention and without lasting effects. However, infants, young children, elderly, pregnant, and immune-compromised individuals are at higher risk of needing medical attention or having complications from an illness. Your location—a remote basecamp in Pakistan or a day hike close to home— will play a key role in the severity of your illness, should you become infected. For more information on diseases caused by specific pathogens, please visit www.cdc.gov.
A filter actually removes matter and microbes from the water while a "purifier" can employ a variety of methods to disinfect the water (such as UV or MIOX® or combination system like the MSR Sweetwater® purifier). A purifier must meet the EPA Guide Standard for Testing Microbiological Purifiers, which requires inactivation of all three classes of microbes: protozoa, bacteria and viruses. Filters in general claim to remove only protozoa and bacteria, making it adequate for most travel in developed countries. Some filters alone can qualify as a purifier, but since they are filtering to such a small pore size, they tend to clog quickly. Essentially the classification as a "purifier" means that the device must be capable of inactivating viruses, as well as protozoa and bacteria.
MSR microfilters remove protozoa and bacteria. The microfilters (MSR Sweetwater® and Miniworks®) that contain carbon can also reduce tastes, odors, some chemicals, pesticides, and herbicides.
Inactivate means to damage a microorganism sufficiently to render it harmless.
To decide whether you need a filter or a purifier, two important factors must be evaluated: water sources and susceptibility.

When evaluating water sources it is important to keep the following in mind: In general, protozoa and bacteria infect both animals and humans and are transmitted to water sources by animal and human waste. In contrast, waterborne viruses are species-specific and therefore transmitted to water sources by human waste alone. As a rule of thumb, remote areas with few people require (at least) filtration while popular areas with many human visitors require purification. If traveling in developing countries with poor sanitation, purification will be your safest choice.

Susceptibility is another good way to determine needs. If the treated water is to be consumed by infants or young children, elderly, or pregnant or immunocompromised individuals, then it is essential to use a purifier for the highest level of protection. Purification is also best for people who tend to get sick. If you rarely get sick and do not fit into any categories mentioned above, then filtration may be adequate depending on the water source.
Micron ratings aren't always the best way to gauge effectiveness. Test procedures for micron ratings vary so greatly that comparing them is misleading. In addition, micron ratings for filters do not tell you how the product will perform with actual bugs. There is an EPA Guide Standard for Testing Microbiological Purifiers, which describes how to test products to determine if they are removing or inactivating the proper number of pathogens in different types of water throughout the life of the device. When looking for a microfilter or purifier ask if the product has been tested according to the EPA Guide Standard and passed. For a microfilter, meeting the EPA Guide Standard means removing 99.9% of protozoa and removing 99.9999% of bacteria in all required water types. To be classified as a purifier, the device must meet the EPA Guide Standard for the removal of protozoa and bacteria as well as virus which must be inactivated to 99.99% in all required water types. All of the MSR filters and purifiers have passed the levels of inactivation required by the EPA Guide Standard with flying colors.
As a result of the September 11 attack and the following concerns about bioterrorism, we have received a number of inquiries regarding our microfilters' ability to protect against such threats. MSR microfilters will protect you from harmful microorganisms that are 0.2 microns or larger. The anthrax bacteria, for example, measures about 8 microns and would be removed by all MSR filters. Additionally, if a water reservoir were contaminated with a biological agent, it is unlikely that enough organisms could be added or would survive the treatment process of the water plant to provide an infectious dose at the tap. Our water supply is more likely to be compromised or cut off completely as a result of a natural disaster, such as an earthquake or hurricane, or by a general state of disorder following any kind of attack or natural disaster. By including a good water treatment device (and knowing how to use it) in your emergency kit, you will be prepared for most situations.
MSR filters will remove some tannins from the water you are filtering. Like other contaminants, they will clog your filter over time, requiring you to clean the cartridge. Tannins will react with disinfectants and can make treated water taste unpleasant. If possible, look for a clear water source to prolong the life of your filter and improve the taste of purified water.
MSR filters and purifiers provide microbiologically safe drinking water. The carbon in the filters and disinfectant of the purifiers will adsorb or react with some chemical contaminates such as herbicides, pesticides, and volatile organic compounds (VOCs). However, MSR filters or purifiers will not protect you from high chemical concentrations or heavy metal contamination. Do your best to avoid water sources such as mining tailing ponds or those near agricultural operations.
MSR filters and purifiers come with a limited warranty. Contact our Warranty and Repairs Department at 1-800-531-9531 if there are any problems with your filter or purifier and they will be happy to help with solutions.

What is California Proposition 65?
Proposition 65 is the Safe Drinking Water and Toxic Enforcement Act passed by voters in the State of California in 1986. The act was created to inform people about possible exposure to chemicals known by the State of California to cause cancer, birth defects and/or other reproductive harm.

What are the requirements of Proposition 65?
Proposition 65 requires that the Governor of California maintain and publish a list of harmful chemicals. The list is updated annually and includes chemicals that can be found in solvents, drugs, dyes, food additives, by-products of certain processes, pesticides, and tobacco products.

A chemical is listed if it has been classified as a reproductive toxicant or carcinogen by an "authoritative" organization on the subject. The U.S. Environmental Protection Agency, U.S. Food and Drug Administration, National Institute for Occupational Safety and Health, the National Toxicology Program, and the International Agency for Research on Cancer are considered authoritative for carcinogens. For reproductive toxicants, the authorities are the U.S. Environmental Protection Agency, U.S. Food and Drug Administration, National Institute for Occupational Safety and Health, and International Agency for Research on Cancer. Chemicals will also be listed if they are required to be labeled or identified as a carcinogen or as a reproductive toxicant by an agency of the state or federal government.

Why has MSR placed a Proposition 65 label on its products?
Any company with 10 or more employees operating or selling products within the State of California must comply with the requirements of Proposition 65. To comply, businesses are: (1) prohibited from knowingly discharging listed chemicals into sources of drinking water; and (2) required to provide a "clear and reasonable" warning before knowingly and intentionally exposing anyone to a listed chemical.

A Proposition 65 warning means that the business has evaluated the exposure and has concluded that it exceeds the "no significant risk level," or that the business is providing a warning based on the presence of a "listed" chemical without actually evaluating the exposure.

MSR is providing a warning based on our knowledge about the presence of one or more listed chemicals without attempting to evaluate the level of exposure. While using an MSR product, the exposure to a "listed" chemical may be well within the "no significant risk" range, but out of caution, we have placed the Proposition 65 warning labels on our products.

Are consumers who are using an MSR product with a Proposition 65 warning at risk?
The California government states: "The fact that a product bears a Proposition 65 warning does not mean by itself that the product is unsafe." The government also explained, "You could think of Proposition 65 more as a 'right to know' law than a pure product safety law."

A Proposition 65 warning means that the product contains one or more listed chemicals. By law, a warning is required unless the business proves that the exposure to the chemical poses "no significant risk." The "no significant risk" level for carcinogens is defined as the level which is calculated to result in not more than one excess case of cancer in 100,000 individuals exposed over a 70-year lifetime. Therefore, if you are exposed to the chemical in question at this level every day for 70 years, theoretically, it will increase your chances of getting cancer by no more than 1 case in 100,000 individuals so exposed.

The "no significant risk" level for reproductive toxicants is defined as the level of exposure which, even if multiplied by 1,000, will not produce birth defects or other reproductive harm. Therefore, the level of exposure is below the "no observable effect level," divided by 1,000. (The "no observable effect level" is the highest dose level which has not been associated with observable reproductive harm in humans or test animals.) For further information about California's Proposition 65, please visit http://oehha.ca.gov/prop65/background/p65plain.html

Lightning vs. Revo Snowshoes: What’s The Difference?

We’ll walk you through their key advantages to help you choose.

Read More
Three Warm Meals for Cold-Weather Trips

Three hot meals to warm you up while winter hiking.

Read More
Tech Talk: Why We use Martensite Steel in MSR Snowshoes

A look at the properties and benefits of this hard class of steel.

Read More
KVG
February 5, 2017
Yes, I would recommend this to a friend
Worked like a charm!
I purchased this purifier to use while hiking in the Blue Ridge mountains. My wife (and admittedly myself) were both skeptical of its capabilities, even after watching numerous reviews. So, I used it on the retention pond water behind my house. i figured, if I need to rely on this in the mountains, I need to trust it first. Well, I can say that I drank the entire bottle of water and lived to tell about it. Great work MSR!
Pete H
January 8, 2017
Yes, I would recommend this to a friend
Love it!!
Purchased this pump after much research. I have been using the MSR Miniworks for years and have loved it. Hike a lot in Hoosier National Forest and pump from lakes and ponds when streams go under ground. The miniworks worked but had to be cleaned every 28-29 strokes due to sediment. I have used the Guardian on two trips since the 1st of Dec (2016) in the same lake and pond. WOW!! First time in 20 to 30° temperatures and I pumped and filled a 48 ounce Nalgene bottle in the time it took my Miniworks to fill about 8-10 ozs ( then had to be taken apart and cleaned). Just used it the past two days and woke up to -1°F and did not stick the Guardian in my sleeping bag like I would've the Miniworks and it was a block of ice, nothing would function or move on the pump. Stuck it between my layered clothing while cooking breakfast and it worked better than great. My brother had just purchased another expensive brand and he couldn't get it to thaw even after sitting it next to the fire. My Guardian prefilter was completely covered in mucky settlement and was easily washed off by just pumping the extra water out and letting it hit the prefilter. Now to the comments on the filter O ring. Yes mine unscrewed at the bottom this trip I believe mostly due to the temperatures. But just looking at it and seeing the large black rubber ring that attaches to your bottles I surmised "hey that looks like a handle thingy with texture to turn with my hand". So once I used it to screw on and screw off the pump and not using the filter body it worked great. Yes they are pricey and like most people I was going to wait a couple years until they came down in price but I'm really glad I didn't
Northwet camper
December 4, 2016
Yes, I would recommend this to a friend
Stay with MSR Filters!
We purchased the Guardian system to replace mid-1990's Sweetwater filter system because cost of buying replacement filters. MSR will replace parts that fail (plus). Primary reason: I prefer a field serviceable ceramic filter rather than worry about when a fiber filter will clog or fail. Compared to the range of options on the market, this is a heavy filter system. But, it is a system, not just a filter, and is flexible for using in a variety of source water quality (high fine sediment use pre-filtering or settling) to type of container (platypus bags, nalgene bottles, etc). Unit has been used extensively for backpacking. It filters so well that filter requires frequent cleaning; pumping capacity falls off quickly (within a few liters even in "clean" source water). For reliability, durability and service-ability, this is a fine unit, For lightweight, no hassle weekend trips, look at other options before buying, And, read the reviews and dont listen to most sales people!

Free shipping on all orders over $100

Available for U.S. addresses only.

We know that in the backcountry, reliable gear is critical. That’s why MSR gear has always been engineered to the highest quality standards and rigorously tested before it reaches you. If your MSR gear is in need of repair, please contact our Seattle Repair Shop at 1-800-531-9531 and our technicians will work to find you a solution as quickly as possible. A majority of the time, MSR products can be repaired. If you are experiencing an issue with your product that you feel should be covered under the MSR Limited Warranty, please visit msrgear.com/warranty for more info.