MSR Sweetwater Microfilter System Review 2016/06/15

Water purification involves everything from local geography and geology – why is there water flowing here and not over there? In this review we will look at the MSR Sweetwater Microfilter.


There is a lot going on with water. It draws upon biology – what can harm me in this water? From a survival point of view – how much water do I need to stay alive? The practicalities – what system is most appropriate for my specific trip? Point of collection – where is the best place to collect water from the wild? If you are unsure about the answers for the questions above, then do some research! You should not rely completely on one piece of equipment as it is not a substitute for good outdoor common sense.

MSR Sweetwater Microfilter

This review will deal with the MSR Sweetwater Purifier System which is part mechanical filter and part chemical solution. The mechanical filter will deal with most nasties and the chemical solution can be added to the filtered water to kill off anything left. The construction of the MSR Sweetwater Purifier strikes a good balance between durability and weight. At 397g the MSR Sweetwater took some beatings in the bottom on my rucksack and survived just fine. Of course some general care should be given to the item as it does contain moving parts along with the adjustable handle you see in the photo below.


The pre-filter is very well constructed and seems very strong indeed, especially good if used in high flow rivers which may knock it around against rocks. The float foam stops the pre filter touching the sediment bottom of the river or stream you are using. Included are several adapters to fit onto bottles, the ever popular Nalgene wide mouth is well served here and it fits directly on to a MSR Dromlite or using the tube straight into a wide mouth Nalgene bottle.


Once you have set the filter up a couple of times it becomes very quick to do, so with the pre-filter submerged and the float helping keep it from touching the bottom you can begin to pump. It takes roughly 75 pumps to get a litre (roughly a minute) and the pumping action is smooth and easy to do. Once you have your water simply disconnect the out tube and lift the pre-filter out of the water source. Now pump again to get rid of the water held within the filter, this is very important so do this each time you have finished collecting water as helps maintain the filter whilst on the trail and stops it leaking out in your pack.

As I mentioned earlier the MSR Sweetwater Microfilter is part mechanical and part chemical. The mechanical section (the filter itself) uses a tiny pore size (0.2micron) and activated carbon core to clean your water of bacteria, protozoa, parasites, physical particulate. The MSR Sweetwater is a microfilter and so only filters the water of large nasties and at the end of the day unless you add some Purifier Solution you are solely relying on the filter itself to keep your water clean. The filter is made of ceramic and can be field maintained using a supplied brush.

Out and About

When travelling in the backcountry your health becomes even more important. If you contract an infection or virus it could mean you have to abandon everything and head home. Worst still an emergency situation occurs where things may get interesting! So its always important to think about where the water your drinking is coming from and if its safe to drink. Its also important to consider on longer trips what chemicals you are consuming to make the water safe. Consequently what these are doing to your health. Ingesting chlorine, chlorine dioxide, iodine or indeed any form of chemical based water purification is not ideal for one's long term health especially if the trip is longer than 3 weeks which is generally the length of advised use for these chemicals. If you are using chemicals then please read the suggested use lengths. Personally I prefer to use the very good mechanical filter of the MSR Sweetwater Microfilter and then boil the water if I am concerned there is something in the water. One of my canoe expeditions involved travelling in areas where you could drink straight from the lakes and rivers. I wish I would have had the MSR Sweetwater Microfilter then as it would have added an extra reassurance that was not chemical based.


These are incredibly small and can slip through the (0.2micron) pores of the MSR Sweetwater. If you are in an area with a known problem, then adding the Purifier Solution will kill them. The solution is made of Sodium Hypochlorite which is a form of bleach or disinfectant. Commonly used but has a wide range of completely unexplored side affects and long term use health issues.


The MSR Sweetwater Microfilter is sadly not field maintainable. The filter is within its plastic housing and cannot be removed. MSR do supply a brush for cleaning the inside if it becomes clogged (which it will through normal use) I would certainly take this on longer trips. The Silica Depth filter used in the MSR Sweetwater holds a lot of sediment before becoming clogged which is virtue of this style of filter medium. The MSR Sweetwater tells the user when the filter becomes clogged. An excellent feature as it prevents pressure damage in the filter. Its called the PRV – Pressure Relief Valve and spurts out water when the pressure gets too high within the filter which is a sure sign of clogging.


Overall I prefer using mechanical methods of filtration over chemical. The MSR Sweetwater would work well with boiling in areas of known virus problems. It would do away the need to use the chemical. Having the equipment to make fire and a suitable container to boil water in are in my mind essential items to be carried into the backcountry. The MSR Sweetwater does have the chance of breaking and so being covered by a plan b makes common sense. The MSR Sweetwater Microfilter is a reasonably inexpensive filter. I would take it to areas where I am reasonably sure the water is ok to drink as passing water through a filter makes it way easier to deal with rather than using complicated fabric pre filters which take a long while to work (such as a mil bank bag). The price of the item makes it very good value in my mind. I will be using it on future trips. During a week in the Scottish Highlands it worked fine without the use of the Solution and I did not get ill. When returning home make sure you dry out the filter completely before storage.


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