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MSR MiniWorks Ex Water Filter


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    115 Reviews


    Keep your water clean for years.

    Filter your water year after year with the MSR MiniWorks Ex Water Filter. Clean this lightweight, compact filter back to like-new condition, without any disassembly tools. The MiniWorks' ceramic element ensures long-lasting protection against bacteria, protozoa (including crypto and giardia), and particulate, and the carbon core removes yucky tastes. MSR's little wonder (7.5 x 2.75in) can filter up to 1 liter per minute. As a bonus, the MiniWorks Ex Water Filter screws onto a standard Nalgene bottle or any MSR dromedary bag.

    • MSR's best-selling micrfilter known by backpackers for longevity
    • Marathon EX carbon/ceramic element ensures clean, tasty water
    • AirSpring Accumulator delivers one liter of water per minute
    • Field cleanable without any tools
    • Includes filter, hoses, stuff sack, hose float, scrub pad, and instructions
    • Item #CAS0479

    Tech Specs

    Purifying Element
    Marathon EX (carbon/ceramic)
    Cartridge Life
    AirSpring Accumulator (pump)
    2.75in x 7.5in
    Claimed Weight
    Recommended Use
    backpacking, camping, paddling trips
    Manufacturer Warranty
    limited 3 years

    Tech Specs

    • Reviews
    • Q & A

    What do you think about this product?

    Have questions about this product?

    Pretty good

    • Familiarity: I've used it several times

    I really like this filter, it has been very useful a long hiking trips with multiple people using it and not having to try to pack a bunch of water. I've read reviews about 30+ minutes to fill a liter bottle. This was not the case for me as it functioned as described. About 80 pumps for a liter, took about 120 seconds or less.
    One problem I encountered was the pin that holds the handle/plunger in place fell out, it must have compressed the little clip during hiking and during use it worked the pin out. I have looked for replacement pins and cannot find them.
    This has not been a huge problem as I have replaced the locking pin with a wooden stick that I found in the woods.
    Just thought I might pass on my experience to others to be aware of.
    The thing I like is that you can visually see when the filter needs replaced by using the measuring tool provided, although you do need to clean it with the green pad, while other filters you cannot visually see when they need replaced.

    Pretty good

    So Far, It's Great!

    • Familiarity: I've used it several times

    I've done a few hiking trips with this water filter, and so far I am definitely pleased. The water I've filtered has tasted clean and I've had no sickness from it. I find the pump slows when filtering water with a lot of sediment, depending on the source.
    I like that it screws directly onto the Nalgene bottles and the clean outlet from the filter is mostly kept protected from any exterior contaminants. It does seem like they put some thought into how the filter will be used and how to design it so to minimize contamination risk from unfiltered water.

    I'd seriously consider buying this again, and highly recommend it to others.


    • Familiarity: I've used it once or twice and have initial impressions

    Haven't had a chance to take this one in the backcountry yet, but have used MSR filters before and never had an issue. This one is just the right size so excited to use it this summer.

    MiniWorks simply works

    • Familiarity: I've put it through the wringer

    I have used the MSR mini-works for over a decade now. The simplicity of this water filter is the key to it's longevity. The pump action is slow - as other reviewers have noted - however it simply works time and time again. Cleaning the ceramic filter with a scotch bright pad is simple and easy. Clean dependable water is key when off the grid and that is the reason to bring along this top performer.

    Not for the PCT

    • Familiarity: I've put it through the wringer

    This may be a good piece of gear for a specific type of trip but it was horrible for the PCT. Regretted buying it and switched to a Sawyer Squeeze about a month in and wish I had switched a month sooner. Not only is it heavy for a water filter, it also takes up a bunch of space in your backpack and its a total hassle to fill water at the end of the day. Needs to be used in puddles..with a Sawyer Squeeze you can fill up from the actual flowing part of the stream in 10 seconds, with this thing you need to put it in the puddle under the flow and pump (arm workout!) for 5-10 mins. Need to clean the filter every once in awhile or the flow rate drops to a trickle.

    Great but takes a little work

    • Familiarity: I've used it several times

    Filters up to a liter per minute but must be pumped at a rate of 70-80 pumps per minute. This is pretty fast and can be a bit of a work out, but that's standard for any pump action filter. It filters well and the water tastes great. Screws directly onto a standard Nalgene water bottle or any MSR Dromedary Bag. Pro tip: definitely pair with an MSR Dromedary Bag. It will allow you to filter multiple liters at once. Waaaay quicker filter process if you have the drom. I filter 6 liters at once and can fill both my fiances water reservoir and my own with a little extra water to spare. Great system for multiple people, a little overkill for just one.

    Good filter

    • Familiarity: I've put it through the wringer

    I have owned this filter for a few years and can't complain. It filters well and is durable, but is a bit slower than some other filters. The other reason I removed a star is the fact that you need a nalgene to pump in to. I have shared the pump with others in my group that brought odd sized bottles or bladders that were not compatible with the filter. Overall, a good filter that I will continue to use for backpack outings.

    Be Aware

    • Familiarity: I've used it once or twice and have initial impressions

    I've taken this with me on two 25 mile backpacking trips. It's light weight and fits inside my pack well. I had one issue on the first trip. The water had a lot of particulates in it and after about a liter of water, the flow significantly slowed. I took it home, cleaned the ceramic filter and took it out again about a week later. This time I came prepared with a prefilter and used that for most of the trip. The last day i decided to use it without it since we had another filter as a backup. It worked surprisingly well considering the issue I had the week prior. However, the water I was filtering was way cleaner and had way less particulates. Loved the filter, water was clean and tasted great. Giving it a three star due to the first issue, but depending on the water you're filtering, the MSR mini works is hit or miss.

    No more iodine tablets!!!

    • Familiarity: I've used it once or twice and have initial impressions

    Frankly, I'm super stoked to not have to use iodine tablets again. The filter does a wonderful job and maintenance is simple. A bit heavy for backpacking, but I don't mind a couple extra ounces.

    Great filter for small backpacking crew

    • Familiarity: I've used it several times

    Filter works great for a small backpacking crew (3-4 people). The ceramic element needs to be cleaned frequently depending on the quality of the water being filtered. Used this one for the first time in the Linville Gorge and had to clean the element about every 8 liters or so to maintain efficiency. Overall a good quality filter.

    Perfect for 2-3 day Hikes

    • Familiarity: I've used it several times

    The water was quite clean to begin with,
    The unit clogs and you have to scrub the ceramic unit with the supplied green pad. It will start working again, but slows down again after a few liters of water. It is physically demanding to use. Not hard, but if you're supplying water to two people on a backpacking trip your arms are going to get a workout along with your legs.

    Perfect fit on Nalgene

    • Familiarity: I've used it once or twice and have initial impressions

    This is the most efficient water filter if you are doing some backpacking and have a nalgene with you. It screws right onto it and the filtering is fast enough and tastes fresh. This is also very light and perfect for a long backpacking trip

    Absolute garbage

    • Familiarity: I've put it through the wringer

    I do not know if I had a faulty unit. However, I do not know who thinks there is a strong business case for a backcountry water filter that filters water at a rate of 1 liter per 20 minutes. I tried this pump for the first time in the Olympic national park, where we were planning to cover 12-20 miles per day. When you are trying to cover that distance every minute in the wild counts. However, we literally wasted 2 hours a day filtering water :S. I am not a newbie, and I used to love the MSR HyperFlow Microfilter, before deciding to try this new pump. My mistake was not to test the pump before hitting the backcountry. The situation got so bad on time spent to pump water that we had to start rationing water in a place where there is water available every single step of the way. That said - AVOID THIS PRODUCT! (in picture - my gf resigned to having to spent 40 mins to pump 2 liters of water in the final day of the trip)

    Absolute garbage

    Always Keep Handy

    • Familiarity: I've used it several times

    I got to use this a lot this past summer on my road trip out west and really loved it. Not a very large system but works perfect when I need to refill my 48oz nalgene. I love that it can screw right on to my water batter, there's no need for another piece to make it functional.

    Looking forward to more adventures and this filter is something I will always carry with me.

    Clean Agua

    • Familiarity: I've used it several times

    This is a fantastic option for a water filtration system. It is small and compact but you can really crank out a decent amount of purified water pretty quickly. I love the fact that this will screw directly onto a wide mouth bottle. This is perfect for backpacking trips in the backcountry.

    Initial impressions are pretty good.

    • Familiarity: I've used it several times

    I've done a few hiking trips with this filter and I really like it, the more I use I the more I like it.

    The water I've filtered has tasted great and I've had no ill effects from it.

    I find the pump rate acceptable and only slows when filtering water with a lot of sediment.

    I like the fact it screws directly onto the Nalgene bottles and the clean outlet from the filter is mostly kept protected from any exterior contaminants. It does seem like they put some thought into how the filter will be used and how to design it so to minimize contamination risk from unfiltered water.

    I do worry about cracking the cermanic filter from something like a fall or dropping it but you could carry a spare filter.

    The filter itself is heavy but overall I don't see it as excessive...I could shed a few lbs to make up for the extra weight of the filter.

    I'd seriously consider buying this again but I know filter technology is always progressing but I do rate this filter highly, four star in fact. I dropped one star for the weight and the concern about breaking the ceramic filter so if that doesn't bother you then boost it to 5 stars.

    Great Purchase

    • Familiarity: I've used it several times

    Started backpacking within the last year and upon picking up gear majority of veteran hikers recommended this. I ignored their advice & instead purchased the Sawyer MINI for easy storage/weight. With EPA water regulations going down the tube, I decided to make an upgrade & purchase the MSR mini. Not yet being on a trip to use it, I've tested/experimented/played with it numerous times to prepare myself for field use. It's simple. It works. And it's great! Plus young kids love watching/learning how it works. Just follow the elementary school type instructions for cleaning & care, it'll last for yrs to come.

    Cons-weight & size for minimalists, &
    $ (for some people)
    Pros- There's a reason it hasn't changed much in design/$ since '97...bc it works perfectly & one of the best filters recommended out there

    Tested True

    • Familiarity: I've used it once or twice and have initial impressions

    Picked this little bugger up for a 3 day trek through Colorado with Fjallraven, but they ended up giving us a Grayl water filter bottle so didn't get a chance to really put it to the test. Initial testing was great, easy to use, adequate speed of filtering and taste was good. Looking forward to putting it more to the test on the Sky Rim Loop in Wyoming later this summer.

    After reading the reviews, I'm convinced this is a high quality, durable filter. I first encountered this filter when hiking in Nepal with some Finnish friends. They used the filter, then used a UV filter on that water. I didn't exactly understand why; something about the MSR being able to filter out something, and the UV being able to filter out something else.

    I would like to ask you guys if this MSR filter is sufficient for pretty nasty water that may have giardia inducing parasites, etc.? Or do you typically use this filter COMBINED with another purifying device like UV or drops?

    I understand that it probably depends on the water source, but thanks for any help.

    Best Answer

    Hey Max,

    So this is a great filter. I've had this filter since around 2008 and as long as I clean the filter and store it properly after each use, it will continue to last me for years to come.

    It has an inner charcoal filter (for tastes and odors) and an other ceramic filter that filters out particles above 0.2 microns in size. So that is almost everything. The one thing this does not filter out are viruses. This is why you saw those people using the UV light (most likely a SteriPen) as a final step to kill any viruses that could be in the water source. Personally I'm not a huge fan on the UV pens as they do not kill everything in the water as there are certain parts of the water that do not come in contact with the UV light.

    An alternative to the UV lights (SteriPens) are tablets such as (Item # CAS0775). The tablets meet EPA purifier standards for the neutralization of viruses, protozoa, bacteria and giardia cysts. So those will work great for treating your water. Only down fall is there is a 30 minute wait time after putting the tablets in the water and then there can be a bit of an odd taste to the water.

    Shoot me an email if you have any questions at all!

    Jared D.

    Expert Gearhead


    I bought one of these a while back and struggled to get it to pump any water through. Not sure if there is a manufactured defect or if I failed to prime it correctly. The priming instructions that come with it are a bit vague. Any tips/more detailed instructions on how to go about priming it correctly and what I should be looking for to determine if I primed it correctly? Thanks.

    Karen, I just came in to post a review and this was going to be a point I would make. I had the same difficulty, except it was after I had initially used it at home. It worked great at home and for a few liters in the backcountry, then became frustrating as I couldn't get much water through it.

    It turns out that after my first use at home, I should have used the green pad with water on the ceramic filter after flushing it clean for the first time. I guess it was dirty, not from water, but maybe dust or w/e during the manufacturing of the ceramic disk. Now it seems to work properly, but only time will tell.

    How do these filters work with sea...

    How do these filters work with sea water?

    Best Answer

    No, unfortunately it will not. The ceramic element is so molecularly "huge" compared to even viruses that it will most definitely not remove sodium ions, which are wayyyy smaller. The carbon filter may help with a lot of solids and even some minerals, but once things are well dissolved in water, the carbon won't do much.

    Bottom line, it will be good for gargling but not drinking.

    You would need a desalinator to make it drinkable, and those will run you ~250 to upwards of 2,000. (google Katadyn Survivor 35 and 06).

    would this be good for unsafe drinking...

    would this be good for unsafe drinking water in Nigeria?

    The only problem is that this (and nearly all) filters are not effective against waterborne viruses, which may be of concern in untreated water in undeveloped countries. It would be a great first step, but you are probably well-advised to treat the water for viruses as well, after its been through the MiniWorks. A UV treatment or some sodium chloride drops/tablets would get you really in the clear.

    This FILTER filters out many things including bacteria. But if you have things like virus in your water source, you would be better off buying a water PURIFIER which can be found sold alongside many FILTERS. They are somewhat more expensive but if you are in an area where the water in your environment is so contaminated; I would go for a PURIFIER instead of a mere FILTER.

    Debating between this and an MSR AutoFlow...

    Debating between this and an MSR AutoFlow (which sounds like it's 2.2oz lighter, will be more friendly to the group, and faster but potentially less versatile and more of a pain in the ass to maintain) for an upcoming 9 day AT trip. Any other advantages/disadvantages I'm missing?

    Big question I have w/ the MiniWorks is connections to my water storage. I'm planning to take a 2L Osprey HydroForm bladder and a couple of 1L Platypus soft bottles for electrolyte drink and temporary water storage and transport at camp. Does the included interface screw onto an Osprey bladder? I believe it's made by Nalgene. If not, can anyone recommend bladder tubing that will definitely fit the nipple on the clean side cap?

    Best Answer

    Hi Sid,

    The AutoFlow is more of a camp type of filter system than one for the trail (see some of the photos of it in use below). That's not to say that it wouldn't work (especially if you're filtering for the whole group at once as you travel), just that the MiniWorks is more suited to just getting to pumping water on the fly. The Autoflow needs to hang or be held up...dependent on gravity, not mechanics.

    Either of the MSR filters use 3/8" tubing. So does the Hydroform. A couple of sets of quick connect fittings strategically placed in the
    lines should give you full compatibility with any of the systems you mentioned. hope this helped.

    Very helpful Phil! I'm progressively leaning towards the MiniWorks for the durability and flexibility, speed/multi-tasking be damned.

    Should these 2 bits let me mount a small section of tubing w/ the male bit of the quick connect kit semi-permanently to the nipple so I can still fill stuff w/ the right threading and use the other section of the tubing w/ the female end of the quick connect for filling narrow mouth bottles/other bladders/etc?

    I got the MSR replacement hose. This fits on the clean end nipple and you can use it to fill the platypus bottles. The Hydraform's cap is too big for the filter, but the hose works just fine. I have had this filter for years with no issues.

    does this pump come with an additional...

    does this pump come with an additional house for the output nozzle? i know some filters (katadyn vario) come with another hose to help fill up reservoirs. i usually hike with a camelbak 3 liter bladder. if it doesn't, is it a problem that can be solved by running to your local hardware store for a tube?

    does this pump come with an additional...

    does this pump come with an additional house for the output nozzle? i know some filters (katadyn vario) come with another hose to help fill up reservoirs. i usually hike with a camelbak 3 liter bladder. if it doesn't, is it a problem that can be solved by running to your local hardware store for a tube?

    Hey there, this filter doesn't come with an extra hose, I am not sure if a water bladder hose will fit to the nipple/output on the bottom or not... MSR says this on how to filter water:
    Place a clean container under the filter OR attach an MSR® Dromedary™ Bag onto the bottom of the filter...

    So basically a water bottle or MSR's specific water bladders...

    I personally use the Katadyn Vario for all general needs and just pull the bite piece from my water bladder, insert this into the bottom of the Vario and then fill the bladder while its still in my pack...

    I use the Katadyn pocket for the nastiest water and then a Steripen when I know the water is clear...

    I'm looking for a clean side cap replacement....

    I'm looking for a clean side cap replacement. Where can I find one?

    Is there anyway to make my miniworks pump...

    Is there anyway to make my miniworks pump faster/more efficiently? when I pump, the amount of water that comes in doesn't even fill the chamber. It pumped much more efficiently when I first purchased it.

    Use the silicone lubricant in the maintenance kit to keep the rubber o-ring sealed more tightly to the chamber walls. It should be applied when you clean it after each trip. Replace the o-ring if that doesn't help.
    Also, when pumping I like to pinch the hose against the housing on the inward push to help force the water down through the ceramic filter instead of letting it escape back out the hose.

    does this one fit on the kleen kanteen...

    does this one fit on the kleen kanteen bottles ?

    I have been using this water filter for...

    I have been using this water filter for several month now but have not tried on any real unusual sources. I will be shipped off to Afghanistan soon and would like to know.

    Do I still need to carry iodine tabs then filter the treated water?

    I hate the taste of those tabs, so I am wondering will it pull the taste out?

    Or do I not need them at all?

    Any help would be greatly appreciated.


    I'm planning a multiday backpacking trip...

    I'm planning a multiday backpacking trip in October for Sipsy Forrest in Alabama and plan to take many more trips within the USA for years to come I'm considering this water filter as well as the MSR mini works. I recently saw both of these in person at an outdoor store. It seemed as though the Miniworks removes the most, yet it still doesn't remove viruses. Should this be of any concern for me in the USA? How can I combat viruses if so? Filter, then boil? I appreciate any input anybody has!!!

    Viruses are usually not found in backcountry water sources in the US though they are not nonexistant. So chances are you could could probably use the Miniworks or another filter for years and never have a problem but it is always a possibility. Viruses are killed by just about any means other than just a filter. Some of the different means are: boiling, chlorine or iodine, mixed oxidants, purifiers and UV light.

    So for your situation if you wanted to get a filter like the Miniworks you could pair it with chlorine or iodine for a good effectiveness. I personally wouldn't recommend using boiling to kill viruses just because I'd rather prefer a method that I can use to kill viruses without having to stop and get out the stove and boil water. While looking at the MSR website too, they make the SweetWater which does cover everything including viruses and is actually a hair lighter than the Miniworks EX.

    I generally use the MSR Miox just because thats what I own and learned to use but I have used some of the other MSR water treatment devices so I would recommend any of them for you. Like I said too, you would probably be fine with the MiniWorks but if you ever plan to go outside the US or just want the peace of mind you might try combining it with another form or getting a different water treament device.

    i've been doing quite a bit of digging...

    i've been doing quite a bit of digging around for a water filter that i can depend on. I have been running into the term 'microns' quite a bit. I am doing an Isle Royale trip in a few weeks and am wondering if this filter will be okay to use by its self. On there DNR site it says a filter should filter .4microns or less for bacteria and 25 microns or less for tapeworm. Will this filter do the job?

    Best Answer

    On MSR's Site they claim it'll filter down to .2 microns... so you should be in business.

    I purchased this filter in December, I...

    I purchased this filter in December, I recently used it on a back country canoe trip in the Adirondack's, it worked great for the first couple of days, and then the steady stream of water turned into steady drops, and when I went to take it apart to examine it, it released a large amount of vapor build up. What is the problem?

    Best Answer

    It's working exactly as it should! That's the good news. Often what is looked at as a disadvantage to many filters is really the key to having a filter work properly. Because the filter element is taking very small stuff out of the water, the pumping action gets harder and harder. The reasons for this is that there are very small, microscopic voids that trap these small microbes that can make you sick (think shoving a basketball through a chain link fence). By default these objects also clog the small passageways that the water needs to get to your bottle. As a result you get a slower filter.

    But because you bought the MiniWorks EX, you're in luck:). All you have to do is simply clean the filter element by, first, taking a good hold of it (if you drop this element on something hard, it will shatter like a porcelain doll). Next take the green bristle pad and lightly scrub it completely. This should only take a few minutes and only a very light scrub is needed. The last step is to re-install the filter element and start filtering away. You should notice a huge difference in the volume of water coming out of the hose. In fact, it should perform as it did when you first bought it.

    The pressure release you experienced is simply the pressure built up while you pumped it. The MiniWorks EX operates using this pressure to force the water through the element. This is known as the 'Airspring Accumulator' molded to the outside of the body of the filter. This is what allows the MiniWorks EX to be the fastest ceramic filter on the market currently. No need to worry about the pressure...

    I've got a barely used older model (blue...

    I've got a barely used older model (blue top) that I'd like to dust off and use again. Are the new replacement parts (orings) and filter compatible with the old model?

    What would water filter/purifier would be...

    What would water filter/purifier would be ideal for international travel. I need one that i can use in pretty nasty water.

    Agree with Gabe- MSR makes first rate filters. However, internationally, viruses become a greater concern, and simple filtration won't do the job of removing them. You're then talking about purification. Boiling, chemical, or UV treatment is the only way to go. SteriPen or Miox (with extra batteries), and chlorine dioxide (MicroPur tablets) is what I would be bringing along.

    Hello. How do I clean the ceramic filter...

    Hello. How do I clean the ceramic filter thoroughly? I alaready cleaned the outside of the ceramic, but water flow is still low? Is there a type of soap that might clean out organic plugging or loosen silt? I have taken care of it. In silty conditions we leave the unfiltered water out overnight so the silt settles. Thanks for any ideas. Brad

    You only clean the outside of the filter, and only use clean water to do so. Soap is a cloggy substance and will be unforgiving to the carbon granules inside the element. The filter is designed to last between 1000L - 2000L (264 - 528 gallons) of use. If your usage is less than this range, you might want to clean other parts of the pump to see if that will give you any improved water flow:

    Will this remove salt from water? If not,...

    Will this remove salt from water? If not, do you have any portable equipment that will remove chloride?Thanks.

    Best Answer

    No, this filter will not remove salt or any chemical that won't bond to carbon. Desalinators are super slow, really heavy and expensive. Unfortunately they aren't typically sold at outdoor gear sites and must be sought after at specialty marine stores or sites. The thing most filters do, including the Miniworks EX, is take out mechanical mixtures, not chemical ones. So, for instance, bacteria, which hasn't chemically bonded with the water is taken out of the water via a very fine strain (0.2 micron strain to be exact). Any thing chemical such as contaminants like pesticides, etc are bonded to the carbon core of the filter. Salt and chlorine derivatives aren't absorbed by carbon and therefore are left in the water.----------------------Most of what Jason says is true here, but salt isn't a chemical bond. The reason salt doesn't come out is that the amount of pressure to force water through a filter small enough to remove salt is absurd. No way you could ever do it by hand.___________________________Right! It is not technically a 'chemical bond' because no new compounds are created. It's simply a dissociation where the water molecules surround the NaCl (salt) molecules, thus dissolving them. The only methods of desalination are 1) electrodialysis, or the use of porous membranes to filter out negatively and positively charged salt ions (ie super FINE membranes); 2) freezing, based on the principle that water excludes salt when it crystallizes to ice; and 3) reverse osmosis, in which pressure, generated by the presence of salt in the water, forces water through a membrane permeable only by pure water. There is no easy solution unfortunately...