ProView – MSR Trail Base Gravity Filter System

Water is often scarce in the desert (if you haven’t heard). I’ve been in some pretty sketchy circumstances on 100+ degree summer days 15 miles into the backcountry only to realize that the promised spring at my destination had run dry. That’s when you go looking for that tucked-away tenaja that has three liquid layers: a top coat of floating death in the form of wasps, bees, and moths, a mid-layer of fairy shrimp, mosquito larvae, and unidentified protozoa, and a bottom sludge of exoskeletons, animal excrement, and other varied gnarliness. So, needless to say, when I filter from any source, no less the aforementioned “oasis,” I want to know that my gear is up to the task.

MSR Trail Base Gravity Filter System

Product Description: To meet the needs of multi-activity backcountry adventurers, we set out to engineer the most versatile water filter ever. The Trail Base microfilter kit features modular components that allow it to be used as a gravity system at camp, a pocket-sized filter on the trail, or a fast-and-light reservoir when you need to carry clean water with you. Whether you’re hiking, biking or basecamping, the Trail Base water filter kit offers incredible flexibility and options, making it the one filter that truly adapts to your adventure and the filtration task at hand.

Offer price: $140 MSRP

  • Quality
  • Features
  • Durability


The MSR Trail Base is a fast and very versatile water filter. Depending on whether you use the gravity filter system or the Trailshot alone, it’s a great choice for van-campers, the expedition backcountry backpacker and day hikers or trail runners.



  • Gravity filtering is easy and almost effortless
  • Small portable Trailshot filter alone is perfect for drinking straight from the stream or filling water bottles on day hikes


  • Dromedary bag “taste”
  • Loosely attached parts are easy to lose


There are certain things that a water filter needs to do:

  1. Filter out the previously mentioned three strata of dank
  2. Keep you from getting cryptosporidium, giardia, and other loveliness
  3. If you’re lucky, get enough of the dank out so that the water tastes artisanal. Unless you are hauling your kitchen reverse osmosis system out into the backcountry, this sweet water effect may not happen. No less, it’s a tall order for a 16.3 oz. piece of gear (versus a 150+ lb. reverse osmosis system). But if the water source is clean enough to begin with, well… artisanal away!

So, on those merits alone, the MSR Trail Base Water Filter passed the test deep in the backcountry of the Grand Canyon, along with the sides of a burgeoning creek in the Gila Box Riparian Area (Arizona) and throughout the Catalina Mountain trails of Southern Arizona. And though I didn’t have to go dipping into a stale tenaja, I generally found the water tasted really good when sampled straight out of the Trailshot filter.

The Gravity Filter

I have to admit that I was wary of the whole gravity filter system. I have been aware of the competing brands who have their own version. But I’m used to the idea of having to put a little bit of pumping elbow and deltoid grease into earning my water for tea and dinner. The idea of sitting around waiting for clean water seems lazy, boring, and ‘un-outdoorsmanly.’ What am I supposed to do while I wait? Stare at the bighorn sheep staring at me from three-quarters of a mile away across a cottonwood-lined canyon? Roast marshmallows? RELAX?! Nope. I’m used to hard labor. I want that bit of fear that I am going to lose my footing and slip into the stream. I want to struggle with keeping the dirty water hose from crossing paths with the clean hose. In short, I didn’t think it was supposed to be easy.

Alas, when using the Trailshot Gravity System, the labor was largely gone. And while I didn’t time it, the filtration went extremely fast. So fast that my marshmallows were charring before I had to start a new cycle of filtration. While the provided two-liter bags are a bit small for my purposes, one can purchase a model that comes with four-liter Dromedary bags instead.

While at first glance this filter appears to be very similar to other manufacture’s gravity models, the Trailshot system has an added advantage. In addition to the gravity system, one can use the filter alone for quick hydration straight out of any water source. So, if you are a trail runner or ultralight backpacker working in a very wet place, theoretically you could get away with using the 5.2 ounce (claimed weight) filter alone without bringing the extra hosing and the “dirty water” and “clean water” Dromlite bags.

There are issues with using ANY gravity filter in the middle of the desert. For one, I have to find somewhere to hang my bags in order to get the gravity flow. The desert was engineered by someone/something with a very sharp and creative mind. My emphasis being on “sharp.” Everything in the desert is prickly and waiting to puncture. Even Nutella has fangs and teddy bears have glochids in the desert. Puncture resistance is something to keep in mind when thinking about any gravity system. That being said, I did run these bags, which are essentially the MSR 2L DromLite bags, across some ridiculously sharp volcanic rock in the Grand Canyon and they didn’t spring a leak. But I know that there are some desert areas that would make the gravity component—hanging bags and avoiding puncture– a lot trickier.

Dromedary bags continued: As I mentioned, the dirty and clean water bags that are included are MSR’s DromLite bags. I’ve had the age-old “odd chemical taste” issue with the regular Dromedary storage bags in the past. MSR swears (three separate phone conversations with three separate representatives/technicians), that this shouldn’t be the case because the issue was resolved a long time ago. But it is the case. I have used several other water storage systems and been able to remove residual aftertaste with a combination of lemon and/or baking soda solutions. However, after soaking these bags for a week, rinsing, and redoing, I was not able to get rid of the taste. The taste bothers some people, but not others. In short, if you have the asparagus-pee gene or whatever gene that triggers this sensitivity, you might want to consider this point carefully. Of course, I had the option to skip the bags and just pump the trail filter, but after about a liter or two, it became exhausting (see climbing gym reference below).

Along these lines, make sure you are ready to sleep with this long oddly shaped… thing… at night when you are out in sub-freezing temps. One good freeze can destroy the filter. I took the risk in mid-20 degree weather in the Grand Canyon and let it rest next to my sleeping bag. But if it were any colder, I would have had to invite it inside.

The Trail Shot System

I was surprised by how much clean water the Trailshot filter was able to generate from each squeeze. In fact, I quickly became accustomed to using the trail filter to fill my extra water bottles when I wasn’t gravity filtering. The advantage to doing this was threefold: 1. I didn’t have to filter into the bag and then pour from the bag into the water bottle (seems a little Rube-Goldberg to me), 2. I was getting free climbing gym prep for my next visit to the crag: pumping that filter enough is like using a Gripmaster or campus board, and 3. it was less time consuming to go straight into the water bottles versus setting up the gravity system.

The Trailshot has a nipple connected to the spout that has a dual use: 1. for trail filtering and 2. it serves as the male connector to the female intake on the clean water bag (grow up… they’re all technical terms.) On several occasions, the whole nipple/spout assembly of the filter actually came off (see picture). This seems like it could be a problem; without that top part, the trail function of the pump is pretty much tanked. And getting the water into the clean bag is going to be a lot harder/less convenient. So… don’t lose it!

The Final Word

I can say with the confidence of being able to write this review from my office rather than the outhouse… this filter works well. If you are an outdoor type that does backpacking trips where you are surrounded by water and you will be making day trips from basecamp, this is the perfect all in one. You can bring the squeeze filter/Trailshot for daytime gallivanting and stop at each babbling brook for a sweet sip straight from the source. At night, you can gravity filter larger quantities. Similarly, if you want the Trailshot capability for day hikes and also want a reliable van camping filter, again, this is your joint. But if you are a desert dweller and can’t rely on the aforementioned babbling brooks, the Trailshot will prove less useful; having a dedicated gravity filter (like the MSR Autoflow Gravity Filter) that will filter large quantities at camp might be better. While you can use this filter for that purpose, the added weight that comes along with the squeeze mechanism could be a real drag for the ounce-counters.

Bottoms up!

Shop the MSR Trail Base Gravity Filter System on Outdoor Prolink. Not a member? Apply today!

Serge J-F. Levy is an award-winning photographer and writer whose work has been exhibited internationally. Though he grew up in New York City and worked there as a professional magazine photographer (ESPN The Magazine, New York Times Magazine, and others), he currently calls the Sonoran Desert his home. He is a professor of photography and is working throughout the Southwest on book projects that relate to the outdoors as a metaphor for the human emotional landscape—and other light topics. You can view some of his work online at or IG: @outdoorframes.

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