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Photo credit: Fiona Outdoors.

MSR TrailShot Microfilter review


Last updated: 24-Oct-18

By Fiona Outdoors

If you need water on the run and do not want to carry a large hydration bladder or you want to rely on the water you find in rivers and lakes, the MSR TrailShot Microfilter delivers clean water every time.

I have been testing the gadget in all kinds for water, from dirty water in the washing up bowl at home, to a muck-filled stream at the bottom of my garden, to a suspicious still pool of water in the hills near Glasgow.


  • Simple-to-use
  • Pocket-sized
  • Lightweight design (5oz/142g)
  • Drink directly form the source or refill bottles/hydration bladders
  • Effective against Protozoa and bacteria
  • Treats: 2,000 litres of water
  • Flow Rate: 1L/60 seconds
  • Price: £40. 


Photo credit: Msrgear.com.

Pros: What’s good about the MSR TrailShot Microfilter

I have tried a few water filters that fit into a traditional bottle but this gadget is standalone and that makes it very useful.

It’s a neat size and easily folds up and fits into a large jacket pocket or a small place in a rucksack.

You can choose if you want to use it on its own; you simply dip one end into the water and use a squeeze action to fill a small soft plastic container in the tube with a mouthful of water, which you drink directly.

It takes a few squeezes to fill the small water chamber.

I advise you try the squeeze action at home first to get the hang of it, but it really does work very well.

Alternatively, you can use the squeeze action to squirt water into a bottle or hydration bladder. There is also a handy way to fit the water delivery tube into the bladder for ease of filling.

The water tastes clean (after the first few goes. See below.) and when I have squirted really dirty water into a clear glass it looks to be pure.

MSR say the water filter will give you clean water free of bacteria, protozoa and particulates and while I can’t test this to be sure it does seem to be clean after filtering. I have been drinking the water and I have not been ill because of it.

The MSR TrailShot has a great endorsement from Jeff Browning, a Patagonia Trail Ambassador and Altra Endurance Team athlete. He says: “It's the first filter I will actually carry regularly on long training runs in the mountains. Everything else has always been clunky or too heavy when trying to stay light and fast.

“I carry the TrailShot it in my side pocket of my shorts and use it when I find water sources. It’s the best and most handy water filter system I have come across and a very useful addition to a trail runner’s rucksack.

The initial price of around £40 does not seem too much for such a smart gadget but see below for a word about the filter replacement.


Cons: What’s not so good about the MSR TrailShot Microfilter

You need to find time to sit down with the instructions to work out how to use it. At first I was quite confused but then, once I understood, I found it easy to use.

When using the filter system for drinking you do get a bit of water overflow. Squeeze too much water into the small chamber and the water spills over the top. This is okay if you are outside, as most people will be, and the water simply spills or squirts on the ground.

I found the filtered water tasted a bit strange to begin with. It has a sort of iodine tinge to it but after a few goes with the system the taste fades.

It can be a bit of a fiddle using the system with a bottle or bladder when trying to fill them up but it does work once you get the hang of it.

The filter does not last forever so you will need to change it at some point and the replacement is £28, which is quite pricey. It states that it lasts for 2000 litres of water but I am wondering how you will know when that is.


MSR TrailShot Microfilter is a great idea and easy to carry with you and use. I like it as a standalone system for times when you know there will be water on a run and so there is no need to carry a bottle or hydration bladder.

It is an excellent way to have a back up for long runs where you are likely to drink all the water you already have with you and need to fill up from a stream or lake. The basic price is reasonable but do remember you’ll need to replace the filter after 2000 litres and that is quite costly.

Design 10/10
Features 10/10
Performance 10/10
Value 8/10
Total 9.5/10

Other water filters you may want to consider:

WATER-TO-GO Filtered Water Bottle
ÖKO Filtration Water Bottle
Katadyn BeFree Water Filtration System bottle

About the writer: Fiona is a keen runner, preferring off-road and hilly to flat and road. She lives in Scotland where the weather is fickle so needs to be prepared for all conditions. See more of what she writes at Fiona Outdoors.

All images Fiona Outdoors except when stated.

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03:33 30-03-18

I purchased the MSR Filter for a run along the Ridgeway during the summer 2017 as there was no way I could carry enough water for the whole run. I had mapped out water sources but found that some had dried up due to the extreme heat. After about 30 miles I had run out of water and was badly dehydrated. Thankfully I saw some horses in a field and guessed there would be a horse trough in the field. The water in the horse trough was really green with lots of insects and floating algae. The Trailshot filtered the water really rapidly and made an excellent job of providing potable water. A real life saver with no stomach issues during the rest of the run.