This photo shows the MSR Trail Base Water Filter Kit near a river.
Chris Maxcer

MSR Trail Base Water Filter Kit Review

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The MSR Trail Base Water Filter Kit is a super versatile lightweight water filtration system for backpacking and camping. The kit includes a slightly modified version of MSR’s popular TrailShot water filter pump, but it also lets you use the TrailShot pump as the filter in a gravity-based filter bag system.

To get us a closer look, MSR sent Man Makes Fire a review unit of its Trail Base Water Filter Kit. This is what we learned:

The MSR Trail Base Water Filter Kit Review

This review photo shows the The MSR Trail Base Water Filter Kit.
The MSR Trail Base Water Filter Kit includes a dirty water bag, a clean water bag, and the TrailShot filter to work as the go-between filter.

Let’s start with the MSR “TrailShot” component because it’s the core filter component for the MSR Trail Base Water Filter Kit: Because you can buy the MSR TrailShot on its own, we took a more in-depth look at it in our MSR TrailShot Review.

Meanwhile, we’ll hit the basics of the TrailShot here: The TrailShot filter component weighs in at about 5 ounces, which is less than half the weight of more traditional pump-style water filter systems like the MSR MiniWorks EX Microfilter.

Despite its small size, the TrailShot can filter up to a liter of water in 60 seconds, which is on par with many more traditional two-hand pump-style filters, and it can filter up to 2,000 liters of water.

This photo shows the TrailShot portion of the MSR Trail Base Water Filter Kit held over a river.
Simply squeeze the TrailShot repeatedly to filter a liter in 60 seconds.

To filter, simply drop the short 15-inch tube with pre-filter into your water source and start squeezing the rubbery bulb around the filter. This sucks water into a chamber and each squeeze forces the water through the filter and out the spout.

It works surprisingly well.

You can hold a water bottle with one hand and work your angles with the TrailShot filter hand and get your bottles nearly full without much trouble.

The downsides to the TrailShot are the short tube, which means you need to bend over, crouch, or sit by your water source to pump. On the upside, for on-the-go drinking, you can simply crouch near a water source, squirt some water into your mouth, and take off down the trail. Lightweight filter straws, like the LifeStraw, require you to lay down near the water source or bring along a cup to use the straw.

Of course, there is much more to the Trail Base Water Filter Kit — the gravity-based filter system.

MSR Trail Base Water Filter Kit Review: Gravity to the Rescue

This photo shows the MSR Trail Base Water Filter Kit connected together.
The MSR Trail Base Water Filter Kit connected: Just raise a full dirty water bag to let gravity do the work.

There are two small differences in design in the TrailShot component: The first is that the pre-filter comes with a threaded base that lets it connect to the gravity system of the Trail Base Water Filter Kit. The second difference is the end spout has a shape and o-ring that lets it also connect to a clean water bag.

If you’re not familiar with gravity-based water filter systems, they’re pretty simple: Usually you have two bags and a filter. The first bag is for dirty water, and to fill it, you simply scoop or fill from your water source. At the base of this unfiltered water bag, you’ll have some sort of filter attached, and in this case, that filter is the TrailShot component.

You attach the TrailShot so that dirty water enters the pre-filter end while the end of the TrailShot spout enters the clean water bag. While this is all fairly intuitive and the bags are clearly marked, MSR includes instructions so that you get it right. Plus, you’ll want to make sure that no one in your party somehow finds a way to use the dirty water instead of the clean water. For example, it’s possible that an inexperienced backpacker or kid might try to use water from the dirty water bag if you left it hanging from a tree.

So, how well does the MSR Trail Base Water Filter Kit work? Pretty well. Gravity filtering isn’t any faster than pump filtering, but you don’t have to crouch over your water source while pumping to fill your water bottles. In addition, with the system you also get an “extra” water bag — you could fill your water bottles while keeping the clean water bag full at camp for cooking. Depending on your backpacking or trail hiking style and the location of your last water source, this could be quite useful. Both bags are 2 liters in volume.

In fact, MSR created this system to be extremely versatile — you can leave the gravity system at base camp and just take the TrailShot portion with you on day hikes.

In our experience so far, there are two kinds of people: those who really like gravity filter systems and those who just want to pump-filter their water and be done with it. I’m more of a pump person, personally, but if you have a group of people to fill bottles for, simply setting up a gravity filter station by using a tree or rocky slope to gain height for the dirty water bag can work out well.

In terms of weight, the gravity filter kit ends up adding about 12 ounces to your filter setup.

One cool feature is the cap on the clean water reservoir — you can use it to fill, pour or drink from. You could put a flavored drink mix into your main water bottle and use the water from the reservoir to cook with.

MSR Trail Base Water Filter Kit Effectiveness

This photo shows the MSR TrailShot portion of the Trail Base Water Filter Kit.
At just 5 ounces, you can take the TrailShot anywhere.

The MSR Trail Base Water Filter Kit lets you safely filter out bacteria (99.9999%) and protozoa (99.9%), making it a safe filter choice for most freshwater sources in North America.

Why just North America? Some riskier international water sources could contain viruses, and the MSR Trail Base Water Filter Kit doesn’t filter out viruses. For that, you would want the MSR Guardian Purifier or use chemical or UV purification as a backup.

All-in-all, the MSR Trail Base Water Filter Kit is one of the most versatile water filter systems you can choose. The TrailShot component gives you ultralight and ultrafast access to filtered water. It’s awesome. The gravity system, of course, lets you avoid the single-hand pump when you need to filter larger volumes of water, making it great for base camp usage. If you tend to go backpacking with your family or in larger groups, the Trail Base Kit will offer you extra versatility from camp to the trail and back. Highly recommended.

Get the Gear:

MSR Trail Base Water Filter Kit

Check shipping/pricing: Amazon | EMS | Moosejaw | REI

MSR TrailShot
MSR MiniWorks EX Microfilter
MSR Guardian Purifier

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