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  • MSR - AutoFlow Gravity Filter - One Color
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  • MSR - AutoFlow Gravity Filter - One Color

MSR AutoFlow Gravity Filter

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    13 Reviews


    Let gravity do the work.

    Collect, filter, and store your water in the backcountry with the quick and convenient MSR Autoflow Gravity Filter. This field-cleanable filter lets gravity do the work and cleans nearly two liters of water per minute. The four-liter reservoir holds enough wet stuff for your whole group, and the adapter end piece fits onto most standard water bottles and reservoirs. It's field cleanable, too, so you can remove all the bacteria, protozoa, and sediment that's been filtered out and have a filter that's good as new in minutes.

    • Hollow fiber filter
    • 4L reservoir
    • Universal bottle adapter
    • Field cleanable
    • Gravity powered
    • Item #CAS003Q

    Tech Specs

    Purifying Element
    hollow fiber
    protozoa, bacteria, particulates
    Pore Size
    0.2 micron
    Cartridge Life
    1500 L
    4 L
    1.75 L / min
    Field Cleanable
    reservoir, filter, universal bottle adapter
    Recommended Use
    Manufacturer Warranty
    1 year

    Tech Specs

    • Reviews
    • Q & A

    What do you think about this product?

    Have questions about this product?

    Compact and Lightweight

    • Familiarity: I gave it as a gift but have feedback to share

    Can't speak for usability or dependability at this point because it hasn't been used. However, it is very lightweight and compact. Instructions are easy to follow.

    Works great the first time.

    • Familiarity: I've used it several times

    I bought a Platapus and this MRS filter at the same time and used them both for three weeks on the Grand Canyon. I drained them and followed instructions. Recently I used them both again and the MRS filter was done. Luckily we had the Platapus and it carried us through the week.

    I would give 10 stars if possible!

    • Familiarity: I've used it several times

    This is so easy to use and is a step up from pumping! The only thing I have to say that is even close to a negative about this filter is that you have to fill the bag yourself! NO issues, solid design and NO MORE PUMPING! I have used this filter on trips with multiple people and kids... this is the way to go. One trick... I remove the small hose from the filter at the black (dirty) end, let a small stream of water pour out from the hose to remove air bubbles form the hose and bottom of the bag, hook it back to the filter and the flow is fine every time! Do the same when back flushing (from other end of filter) and the flow rate is not slowed down at all!

    My fav filter

    • Familiarity: I've used it several times

    I love this filter. Over the last year I've really gotten into backpacking and I've had a chance to use a wide variety of filters ranging from The Sawyer to different pumps. However without a doubt this is my favorite. It's relatively small and pretty light but unbelievably fast and easy to use. If you can manage the size and weight I'd definitely recommend buying this product.

    Problem I'm Having

      I've been able to filter water fine on my first trip, but I've tried backflushing it several ways at home, with my camelbak hydration pack and several water bottles, but it doesn't work at all, no water flows through at all. At first I figured it was because a vacuum seal, but I left the camelbak top open when trying with that. Any tips?

      Never pump again

      • Familiarity: I've used it several times

      Packs up small and lightweight, filters water super fast. Almost zero effort involved in getting 4 liters of clean water. Just fill up the dirty reservoir, connect the filter element and whatever you need to fill up, and let it go!

      Step Up from Pumps

      • Familiarity: I've used it several times

      Using gravity instead of muscle is a great improvement. The fill bag is large and the tubing and filter are simple to assemble. As with anything new you have to get in the rhythm of two filter fills to one backwash cycle. As others have said, clearing small bubbles is critical. Went to Yosemite high country and filtered water for group of seven. All were converts at the end of the trip. The only time we got the advertised flow was the first time we used it. It slowly clogged with the lake water we used and had to be backwashed religiously with filtered water to increase the flow again.


      • Familiarity: I've put it through the wringer

      I used to hate having to go back to a river from camp just to refill my nalgene. No more! I can get multiple refills from camp. It's super easy to use and compact. The cap on the fill end is perfect for keeping contaminants out.

      Consider me a convert

      • Familiarity: I've put it through the wringer

      I just completed three days on the Timberline Trail on Mt. Hood in Oregon. The Autoflow kept my 3 hiking companions and I stocked with fresh filtered water with no problems the entire trip. The flow rates were much better than expected and easily met the 2 L /PM as advertised. We each were able to fill our 3L hydration packs in the time we'd watch other hikers take to fill a single 1L Nalgene. Be sure to hang the bag high to eliminate any air bubbles and let gravity do the work. The bag is bombproof and the included mesh storage bag makes stowing and accessing the filter very easy. I will never pump water again.

      Won't ever use a pump

      • Familiarity: I've used it several times

      Easy to set up, easy to use. As others have noted, it's amazingly fast and the bag is awesome. I've not used in murky water yet, but mountain stream water was crystal clear and tasted great. I still carry backup MSR Aquatabs as others have noted, but ultimately felt super comfortable with this. Highly recommended.

      Rocks with a bit of effort

      • Familiarity: I've put it through the wringer

      Amazingly fast if you take time to completely clear air from filter (shake filter to help release trapped air) and tube, otherwise more or less average flow. Worth the time to get flowing right if you'll filter several liters of water.

      Keep an eye on bottles\containers or you'll end up with water everywhere. I've overfilled many when I underestimate the flow from this filter.

      Has pre-filter in bag which strains all but fine particles. To clean pre-filter flip the source bag inside out and swish in source water.

      Make sure source bag is full, hang high so tube goes straight down, and leave clean side adapter a little loose to allow air to escape as water fills for best performance. If air can't escape as container is filled air will compress and ultimately slow/stop the flow of water, you shouldn't have a release of air when adapter is removed.

      Use included clamp to stop water flow while switching bottles to avoid a big wet mess.

      Pack source bag with snow and hang from pack or otherwise place in sun to melt and save some fuel.

      Includes screw on cap to protect clean side adapter when not attached to bottle or other clean container

      After using this I won't go back to pump filtering.

      Always carry a backup option, I keep MSR Aquatabs in my first aid kit.

      Great but not Perfect

        A vast improvement over pumping. So nice to focus on other tasks while you filter an enormous amount of water. Filter rates of 1 L a minute though are highly optimistic. The biggest issue seem to be air bubbles which get lodged in the filter medium. These can be removed by backflushing after you filtered a half liter of water or so but still the filter rate was never close to what was claimed. Maybe in a crystal clear Alpine stream but I was working with murky desert water.

        The dirty water bag seems bomber compared to the competition and dromedary bags are still the best. Filter seems a bit fragile but is easily replaced.