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MiniWorks® EX Microfilter

The best-selling filter on the market, delivering long-lasting, fully field-maintainable water filtration.
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The MiniWorks EX microfilter is the worldwide best-selling microfilter, delivering long-lasting, field-maintainable water filtration in demanding environments. Engineered for frequent and heavy use, it utilizes our workhorse Marathon EX carbon/ceramic element to ensure clean, reliable and taste-free water. Thanks to its innovative AirSpring Accumulator, it’s capable of pumping one liter per minute and the flow rate can be renewed easily and repeatedly in the field—no tools required. It’s lightweight and compact and, most importantly, been proven reliable by thousands of adventurers just like you.

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  • Testing: Meets NSF protocol P231 for removal of bacteria (99.9999%) and protozoa (99.9%) from beginning to end of filter life in “worst-case” water.
  • Reliable: Durable carbon/ceramic element ensures safe, taste-free water—even with frequent, heavy use.
  • Field-maintainable: Can be cleaned repeatedly for full filter recovery with no tools required.
  • Fast Flow: AirSpring Accumulator increases filtration speed; up to 1-liter per minute.
  • Better-tasting Water: Carbon core removes unpleasant tastes and odors caused by organic compounds, such as iodine, chlorine, and pesticides.
Made in the USA Section Hiker | Top Pick 2019
1 lb
0.46 kg
2.75 in
7 cm
7.5 in
19 cm
5.5 in
Ceramic Plus Carbon
1 liters per min
~2000 liters
Made in the U.S.A. of U.S. and Imported Materials
Can I upgrade my old MiniWorks with an EX filter?
Marathon EX ceramic cartridges are compatible with all WaterWorks and MiniWorks microfilters, old and new. Using it in a pre-2003 filter will increase a MiniWorks filter's output by approximately 25%, thanks to the new AirSpring Accumulator.
What are the materials in the EX filters?
The Marathon ceramic element is made from diatomaceous earth that's heated to the point where it just begins to melt. Most particles are caught within about .005 inch of the surface. When it clogs, you abrade away the clogged pores, making them immediately ready for more use, with almost 100% recovery after each cleaning. Marathon ceramic provides long-lasting protection from protozoa and bacteria. A block carbon core reduces tastes, odors, some chemicals, and many pesticides. The WaterWorks microfilter also incorporates a PES (polyethersulfone) membrane filter, which passes the test for a sterilizing or pharmaceutical-grade filter. It serves as a safety net, providing a second fail-safe seal.
How long will my ceramic filter last?
How long a filter lasts will vary radically from one water source to the next. The ceramic element can last up to 2000 liters. Filter-life ratings are based on best-case scenarios because the testing is performed with clean lab water. Generally you can assume that your filter will last between 50 and 100% of the rated life.
How much water will my filter pump before clogging?
Normal conditions may allow a user to filter between 10 and 20 liters between cleaning. Please note that water quality varies a lot with the season and water source. In general, the more turbid (cloudy) the water, the more frequently your filter will require cleaning and eventually replacement. The MiniWorks is one of the most cost-effective portable treatment devices currently available.
Why is the handle on my filter so hard to push?
There are three possible causes of this. The most likely is that one of the microfilters is clogged. Review the instructions for cleaning the ceramic filter. The PES membrane (WaterWorks microfilter only) may also be clogged. It will have to be replaced or removed altogether. Lastly, the piston O-ring may be very dry, causing friction. Lubricate it with the silicone lubricant provided in the maintenance kit (or use lip balm or petroleum jelly).
Why is the handle on my water filter so hard to pull?
If the handle is hard to pull, something is obstructing the flow of water into the filter. Clean the inlet foam and remove any kinks in the inlet hose.
Why does the handle on my filter feel limp when pumping?
The most common reason for a limp handle is dirt under the umbrella valve. Remove the head of your water filter to expose the umbrella valve. Rinse under it or pull it off and rinse. Reinstall.
Why does my filter squeak when I am pumping?
The squeaking you hear is probably caused by actuation of the pressure-relief valve. This valve is designed to release when there is excessive pressure. Water goes back out the intake hose so you stay dry. You can tell if your relief valve is releasing by watching bubbles in the intake hose—if they go back and forth when you pump, the relief valve is working. It may be time to clean your ceramic filter (reference your owner's manual for complete details), or maybe you are pumping too fast. Do not pump faster than one stroke per second for best efficiency. Older MSR filters sometimes squeak in the pump head, piston pins, and bushings. You can eliminate the squeak with a tiny dab of lubricant on these parts. Newer MSR filters have the lubricant molded right into the pins and bushings, eliminating the squeak.
How should I store my EX filters?
Remove the ceramic element and air dry for 3–5 days. This will prevent growth of mold, mildew, and bacteria. Wash and dry other filter parts thoroughly before long-term storage.
I forgot to dry out my filter before putting it away—what should I do now?
The ceramic cartridge, which comes as standard equipment in the WaterWorks and MiniWorks, can be boiled to kill bacteria that may grow in it. Always let the water cool down before removing the ceramic cartridge from the water. Removing it early can damage the plastic end caps. (Cold water can be added to the hot water to speed this process.) Dry thoroughly before storing. FYI: Because the WaterWorks microfilter has a bacteria-proof membrane immediately downstream from the ceramic cartridge, bacteria cannot get into the water you drink even if it grows in the ceramic.
What happens if my filter freezes?
If you anticipate that you will encounter freezing temperatures, make sure you drain the filter of excess water after each use to protect it from damage. If the filter does freeze, bring it inside the tent or other warm place to thaw, or follow the directions (in the instructions) for boiling the cartridge.
Can I use the Sweetwater® Purifier Solution with the MiniWorks?
Unfortunately, no. The SweetWater Purifier System and Solution are regulated by the EPA and have undergone extensive laboratory testing to verify their efficacy as a system. SweetWater Purifier Solution is carefully formulated to inactivate viruses remaining in water that has been pumped through a SweetWater Microfilter. Filters vary in performance and it is likely that more or less disinfectant may be required to achieve purification with other filters. Along the same lines, for the solution to work independently of a filter, you would need a very strong dose—to the point of tasting offensive. The wait time would also be much longer than five minutes. Finally, cryptosporidia, which would have been removed by the filter, would not be effectively inactivated by use of the SweetWater Purifier Solution alone.

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At MSR, we take pride in engineering the highest-quality outdoor gear available, and we stand behind everything we make. MSR gear is built to be exceptionally durable and easily repaired. And we back it up with the best service in the industry, all to keep your gear performing for you—and out of landfills. Visit our MSR Warranty page for more info.

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