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  • Platypus - GravityWorks 4.0L Filter System - One Color
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  • Platypus - GravityWorks 4.0L Filter System - One Color

Platypus GravityWorks 4.0L Filter System


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    20 Reviews


    The easiest water filtration system around

    If the GravityWorks 4.0L Filter System is pretty dang easy to operate, and there are plenty of devotees who can't get enough of the world's simplest water filtration system. Just fill one of the Platy Zip bags with water, place it above the empty bag, open the hose clamp, and let gravity do the rest. In 2.5 minutes, you'll have four liters of clean water, and if camp is far away, fill the other bag to carry back with you and clean when you need it. Open the hose clamp to dispense water, and shut it to stop the flow. To clean, simply reverse the bags for four seconds, running water through the filter in reverse. That's seriously it.

    • Two 4L Platy Zip bags
    • Filters 4L in 2.5 minutes with no pumping
    • Meets all EPA guidelines for removal of bacteria and protozoa
    • Shutoff valve for easy use
    • Four-second reverse-flush cleaning
    • Item #CAS001G

    Tech Specs

    Purifying Element
    hollow fiber
    protozoa, bacteria, particulate, giardia, cryptosporidia, E. Coli, salmonella, cholera
    Cartridge Life
    1500 L
    4 L / 2.5 min
    Field Cleanable
    yes, backflush
    3 x 9.5 in
    Claimed Weight
    10.75 oz
    Recommended Use
    hiking, camping, backpacking
    Manufacturer Warranty

    Tech Specs

    • Reviews
    • Q & A

    What do you think about this product?

    Have questions about this product?

    Perfect Water Filtration!

    • Familiarity: I've used it several times

    This is a simple, effective, reliable and easy to use water filtration system. We just used it along the Buffalo River in Arkansas and it filters 4L of water in just a few minutes. Highly Recommend!

    Convenient and reliable

    • Familiarity: I've used it once or twice and have initial impressions

    Having a gravity filter automatically filtering water without a pump is certainly convenient, but what really surprised me was how effective and reliable this filter was in questionable water. We were backpacking along the Escalante, a small river that's so murky we couldn't see our feet when we were ankle-deep. I filled the bag with the brownest water I've ever filtered with doubts, but this bag provided crystal clear water, then packed down small for the trek home.

    Works like a dream

    • Familiarity: I've used it several times

    Used the 4L version on a 3-day, 38-mile backpacking trip. We drank a ton of water and even brought a pocket shower to stay clean with. Packs down small, is super easy to use, and filters quickly. Fill the dirty reservoir with water before starting to set up camp and you'll have 4L of clean water well before everything else is set up.

    Saving energy!

    • Familiarity: I've used it several times

    Less pumping is fantastic! Loaded this thing up for a 3 day/4 night float trip, and it did not disappoint. we had 2 rolling for 5 people and had water quickly, with drastically less effort. A great product.

    Hope to never pump a water filter again!

      This filter is perfect for 2-4 people. I go to my water source, and fill the dirty bag with 3ish liters. Then I filter that and fill up the dirty water bag again. so at camp I have 7ish or so liters! I cook a lot so I have pans to clean up. When you are 1/4 mile from a water source this filter is awesome! I took it out late last season for the first time. What a great filter! No more pumping water in awkward positions, or anything of the sort! I always feel like I can drink plenty of water. I have only used this at a lake, not a river, so I would guess if you had a running stream or creek of water you would fill the bag with the full 4 liters. I didn't put a stop watch on time it took to filter. But it seems to filter more quickly than my hiker or water works. Get this filter if you are hike with a group, need water for cook clean up, or camp away from your water source. Great product!!!

      Fast and amazing product

      • Familiarity: I've used it once or twice and have initial impressions

      Just used this over a weekend in the Pacific Northwest. This was super easy to use, produced a large amount of water quickly, and was 4 times faster than the pump style filter a friend was using.

      Excited to use it

      • Familiarity: I've used it once or twice and have initial impressions

      I purchased this filter system after owning the Platypus hydration bladder for a few years. I love the wider opening at the top for filling and cleaning. When I was looking for a filter system, I stuck with what I liked and went with the Platypus. This will live in our camping box for this summer and I can't wait to use it.

      Sent it to family in PR after Hur Maria

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

      Family reports that the system works great and its easy to use. After Hurricane Maria, the family needed a way to filter every drop used for household consumption, and this system has worked like a champ to make sure the water filters out the bacteria that causes leptospirosis. It's been a life or death situation and I'm happy to report everyone has been in good health after drinking the water filtered with this system.

      Convenient and Quick

      • Familiarity: I've used it once or twice and have initial impressions

      I have used this a couple times backpacking in Kentucky. It filters high volume at great speed and is lightweight. Murky river water came out clear (and safe, I assume, as we did not got sick.) The wide opening helped capture a trickle from a rock overhang. So far so good.

      Excellent lightweight water filter

      • Familiarity: I've put it through the wringer

      This is an overall excellent water filter. I have found it particularly useful on extended backpacking trips. It is totally worth the water weight it will save you. With this, I just about never find that I have to carry more than a liter or two of water, unless I am worried that water sources will be scarce.

      The filtration is very easy and intuitive. The buckle on the top of the bag makes it very easy to hang from a tree branch, so that you don't have to stand there holding the bag.

      The filtration is quite fast. It takes only a minute or two to filter 4 liters of water, so long as your filter isn't damaged or significantly clogged.

      Buying replacement parts is very easy. At the same time, the number of parts can make losing the parts somewhat easy. I know I lost the cap to the clean reservoir once (I did find that a regular disposable bottle cap from bottled water or soda you buy at the store can fit on just fine). I also believe they could design this using one less tube (likely the one leading to the clean reservoir), but I could be wrong, and they may have thought of that already. I would really like to find a way to feed it directly into my MSR Dromalite reservoir.

      Be careful not to filter freezing or near freezing water. You will damage the filter. I learned that the hard way. This filter isn't great for alpine environments for that reason. If you are near snow you can just melt that. Otherwise, you will have to put the water on a stove first to melt any of the frozen water, which can be a lengthy process.

      One complaint I have is that the tubes are designed with a sort of material that seems to just be a magnet for dirt and debris. I have found this kind of annoying.

      All said, this is an amazing filter that will clean out any bacteria and debris leaving for great tasting, clean water (note, viruses can still get through).


        After using a MSR hand pump to filter my water, I decided to give a gravity filter a chance. Needless to say, it has made filtering water much easier and extremely convenient. Although it can be hard to get the dirty bag filled up with smaller water sources, a scoop of some sort has fixed that problem. I also love how I can removed the clean hose from the filter and use it to fill whatever I need, whenever I need it.

        This thing is amazing!

        • Familiarity: I've used it several times

        I have used the 2.0L which is what made me want the 4.0L. The reservoir is especially nice. This packs up pretty small and filters/holds a lot of water. Great for groups and needs little effort to use.

        Gravity is King

        • Familiarity: I've put it through the wringer

        I will never use a pump filter again after using one of these. No more crouching by the creek furiously pumping water into Nalgene after Nalgene. Just fill the dirty water bag up, hook it up to the filter and clean water bag, then forget about it for a couple minutes, boom 4 liters of water.

        We used the gravity filter on four day trips for 15 weeks. It never failed us, never got clogged, and with 4 people we always had enough water. When water began to get scarce up high we could use the bags to carry 8 liters of water up to camp. Like previous reviewers, you need to be careful of the filter freezing at night. As far as durability, I hauled mine all around Thailand and Cambodia in the bottom of my pack for 7 weeks and it still works like a charm.

        Unanswered Question

        What is the best way to dry the reservoirs? Having some trouble getting the moisture out after use.