Platypus GravityWorks 4L Water Filter System Review

  • Car Camper
  • Wilderness Backpacker

Platypus GravityWorks 4L Water Filter System Overview

Gravity has never been my friend. Porcelain plates quiver at my touch. I can’t ski (downhill or uphill) and I trip constantly. This particular issue should probably be reported to search and rescue, seeing as I solo backpack at least twice a month. The Platypus GravityWorks 4L Water Filter System appears to lie outside these gravitational problems, because it has filtered water reliably and quickly for me and, can I just say, makes me enjoy physics a whole lot more.

Easy to use, lightweight, and versatile, the Platypus GravityWorks 4L Water Filter System is a set-it-and-forget-it filtration system that’s great for soloists and groups alike. It has helped to redefine backcountry water filtration, and is our Premium Pick for the Wilderness Backpacker and Car Camper.

Check out the full review of the Platypus GravityWorks below and make sure to visit our comprehensive Guide to Water Filters and Purifiers if any aspect of water treatment is unclear. Water treatment is crucial when in the backcountry, and choosing the right system for you is key.

GravityWorks 4L Water Filter System Specifications

Feature Type Feature Specs What This Means
Weight 10.75 oz. (305 g) Not the lightest filter setup on the market, but it beats most hand pumps. Individual pieces are very lightweight, so it can be broken down for less weight.
Filter or Purifier? Filter Removes bacteria, protozoa, and particulate from the water before you drink it. Does not filter viruses. Further explanation in our Guide.
Treatment Type Gravity Hang it up and gravity filters your water for you. Kind of awesome. Details on this and other treatment types in our Guide.
Effective Against Protozoa, bacteria, and particulate This filter doesn’t kill viruses, but it gets what’s commonly found in the backcountry.
Filter Pore Size (Microns) .2 microns Standard size for filters. Further explanation in our Guide.
Filter Media Hollow Fiber Hollow fibers filters are industry standard. They work extremely well, but if used in sub-freezing temperatures they will be rendered useless.
Flow Rate 4 liters in 2.5 minutes Crazy fast, especially when you’re literally letting gravity do all the work.
Filter Life 1500 liters A decent lifespan on the cartridge, but not the best out there. Filters the full 4-liter capacity roughly 375 times.
Filters Particulate? Yes Gets sediment and other bits of out water, but it won’t have a huge impact on swampy smells.
Components The filter
2 hoses
1 4L dirty bag
1 4L clean bag
Shutoff clamp
Storage sack
Water bottle adapter
All the pieces you need, and more. The shutoff clamp is clutch, and the water bottle adapter works pretty well if you’re filter into something other than the 4L clean bag.
Works With Quick Connect Bladders and Bottles Quick Connect port makes it easy to hook up a bladder, while the water bottle adapter allows secure filtering into a bottle of your choice.
Manufacturer Warranty Limited Lifetime Warranty All products have a lifetime warranty, and Platypus (owned by Cascade Designs) offers a repair service as well. Does not include general wear, so the cartridge won’t be replaced for free after many uses.
Cost $119.95 A premium price for a fully featured gravity filter.

Gear Review of the Platypus GravityWorks 4L Water Filter System

Origins: Easing You In

I’m a filterer. Some people are boilers. Some people are chemists. I’m a filterer. I’ve always preferred filters as my method of water treatment because they’re simple (at least they should be!), cost-effective, and they remove crunchy particles from your water. I really don’t have time to run water through a dirty bandana — I’d rather be hiking — and I believe a water treatment method should get sediment and pathogens in one go.

I also don’t backpack in groups often, so when I received the GravityWorks to test, I cringed at what I thought was going to be a heavy, bulky filter. It turns out the packaging weighs as much as the filter setup, and I was stoked to stow the full system in a small corner of my pack for an overnight in the foothills of the San Emigdio Mountains northwest of Los Angeles.

platypus gravityworks 4L-Water-Filter-System-bag-and-filter
The filter and carrying case nestled on some nice, cold snow.

For those not in California, know that it has been a wet winter. The mountains had a spotty blanket of snow at the trailhead and the creek that runs parallel to the trail was flowing with meltwater. I hiked in without incident (except for some near trail misses in slushy, sticky mud), and found a beautiful campsite at Lilly Meadows. The sun was still high, so I set up my tent, unpacked my sleep system, and sat down to rest.

platypus gravityworks -4L-Water-Filter-System-campsite
Nothing like the outdoors.

But I know myself: If I sit down for too long, I’ll never get up. After making camp, the backpacker’s first main chore is collecting water. Moving from a comfortable spot to fetch water is one of my least favorite activities. The stream was close (and full), so I reluctantly got to work.

Revelation: The Moment I Knew

As I mentioned, I’m a filterer. There are lots of types of filters on the market, and I’ve used the same leading brand of hand-pump filter for ten years — it has worked great for me. That said, pumping water constantly for myself can get old fast, and pumping for three people usually leaves me sore and bitter.

I walked down to the creek, unpacked the GravityWorks filter, and marveled at the simplicity: two bags, two hoses, and a filter cartridge. That’s it. There are small attachments that you can use for cleaning or helping water flow, and each four-liter bag is separate (so one can be left at home if you want), but the core of the filter system is fairly minimal.

platypus gravityworks 4L-Water-Filter-System-components
Two bags, two hoses, one filter. And the carrying case for good measure.

I took the “DIRTY” bag and dipped it in the water. With that simple 7-second swoop my filtering was essentially complete. I walked back to camp, hung the bags, attached the filter, and two minutes later I had four liters of ice-cold, fresh, filtered water. What have I been doing with my life?!

In case you’re wondering, four liters for a single person is a ton of water. The GravityWorks 4L is really meant for groups, but I found it’s light enough to work for a solo backpacker. (There’s a 2L version if you never want group capability, but it only weighs an ounce less.) I was able to wash my hands before dinner, refill my CamelBak, grab water for my dehydrated meal, and brush my teeth, all with the one batch of filtered water, and all with the same ease as going to the kitchen faucet.

This was the moment I knew the Platypus GravityWorks worked: It made camp feel more like home and cut down on a typically boring backcountry chore.

Digging Deeper

The GravityWorks is a well-thought out piece of gear. The zip-top opening on the “DIRTY” bag is convenient for grabbing a lot of water quickly. It can be tough to align the grooves of the zip, especially after dipping into a finger-numbing creek, but it’s not a deal breaker. I also love that the port for the exit hose is a Quick Connect — it makes attaching the included hose simple. It also self-seals for transport if you’re storing dirty water for filtration later, and makes attachment into a hydration bladder easy, if that bladder also has a Quick Connect (most do these days).

Both the “DIRTY” and “CLEAN” bags use durable webbing with side release buckles to hang the bags on trees and rocks or to attach to your pack. This allowed me to create a kitchen area for filling bottles and washing dishes easily (away from camp and water sources per Leave No Trace guidelines of course) and, if I’m honest, kind of fun.

platypus gravityworks 4L-Water-Filter-System-using-water
Easy hanging means easy chores.

The shutoff clamp is the smallest piece, but it does so much. Not only does it solve the soaked shoes and muddy mess problem of your water station (clamp the hose when you don’t want water to filter), it allows you to remove the filter from the setup and use the “CLEAN” bag alone as a water storage container and dispenser. The GravityWorks as a whole has no moving parts, which makes it highly functional and easy to use.

platypus gravityworks 4L-Water-Filter-System-water-bottle-shutoff-clamp
Shutoff clamp for the win!

It comes packaged in a mesh storage bag, which is big enough to hold all of the components and also creates a nice, packable bundle that can fit in large trekking packs and day packs. The open mesh also allows for components to more thoroughly dry and helps mitigate musty smells and flavors in your water.

Temperatures on this trip dipped into the mid-20s overnight, and my filtered water froze while hanging in the wind. I wish I would have put it in my vestibule, but hindsight is — well, you know what it is. Luckily, I stored the filter cartridge in the tent with me (more on why in a bit).

platypus gravityworks 4L-Water-Filter-System-water-turned-to-ice
Yes, this water froze. It’ll be icy fresh to drink soon enough…

Ease of Use

“Ease” is the key word when describing the GravityWorks. Fill the bag, hang it, attach the filter, and bam: four liters of clean water on tap. Backflushing is as easy as reversing the bag positions relative to each other. Seriously: what the hell have I been doing pumping water like a chump for ten years?!

Durability

As a broke backpacker, I am no stranger to cheap knock-off ZipLock bags. Platypus did not skimp on their reservoirs. They use tough, flavor-free plastic bags with durable closures. The shutoff clamp is very convenient, but I speculate the thin plastic would be the first component to snap.

Also, a word of warning: hollow-fiber filters are susceptible to damage when in freezing temperatures, so think about how frequently you go out in winter or be sure to insulate your filter from the cold. This is true of all hollow fiber filters, not just the GravityWorks. For this trip, I sucked out as much water as I could from the filter, rolled it up in my beanie, and stored it in the brain of my pack in the vestibule of my tent. This proved sufficient. In extreme low temps, consider putting the filter in a zip-top bag and sleeping with it in your sleeping bag.

Portability

The GravityWorks packs down relatively small for transportation. I even brought it along in my running vest for a 15K trail run into a local canyon. The bladders roll into themselves and the filter itself is small. The included bag stores everything easily, and setup is a breeze pretty much anywhere. There are some small pieces that can blow away or fall into a stream, so be careful not to lose the filter barb cap or clean water cap.

Filtration Rate

The GravityWorks is lightning fast! It takes less effort and has better speed than my hand pump. I found the flow rate is higher if you just put the “CLEAN” bag on the ground or as low relative to the “DIRTY” bag as possible. If you hang them side-by-side, gravity can’t do its job, and the marketing team at Platypus will be bummed.

platypus gravityworks 4L-Water-Filter-System-filtering
A full 4L bag filters in about 2.5 minutes. Not too shabby.

Grievances

I have two beefs with the GravityWorks — well, three, if you count my inherent issue with gravity itself.

First, it’s not always simple to scoop the water. This wasn’t an issue during this test period because the streams were full, but I’ve been in situations with other gravity filters where I struggle to get water from the shallow spring or puddle into the dirty bag. The “DIRTY” bag on the GravityWorks is large, so I could see running into difficulties when trying to coax water out of shallow sources. Most folks counteract this by using a disposable water bottle that’s been cut down into a shallow scoop.

platypus gravityworks 4L-Water-Filter-System-filling-the-bladder
In flowing water filling the bag is easy. In shallow water it would be much more difficult.

Second, there isn’t really a way to separate the “DIRTY” components from the “CLEAN.” You can detach the “DIRTY” hose and put it inside the “DIRTY” bag, and the filter comes with a cover for the “DIRTY” barb. But all of this gets stuffed into the same bag as the “CLEAN” bag and hose. Some other filters come with a zip-top bag or compartmentalized storage sack to keep everything separate. I would use a cheap zip-top sandwich bag as a long-term solution, but they aren’t very durable and require replacement every few uses.

Final Word

I love having ripped forearms as much as the next guy, but the Platypus GravityWorks 4L Water Filter System is so simple and fast, I wonder why I’ve been pumping for all these years.

Where to Buy Platypus GravityWorks 4L Water Filter System

The GravityWorks 4L Water Filter System was tested for this review. It comes with all the components listed in the Specifications table. Platypus also sells the system with 2L bags, instead of 4L bags. It’s $10 cheaper, and meant for solo trips or 2-person groups. It does weigh about an ounce less, but we’ve found that having larger bags is usually better in the long run. Both systems are listed below. For reference, a replacement filter cartridge costs $54.95 at the time of writing.

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Sebastian Cancino

Sebastian is a contributing reviewer for Backpackers.com. When he’s not hiking, backpacking, and snowshoeing in the southern California mountains, he's running his online vintage outdoor apparel and gear shop, Vintage Outdoor. Sebastian works for Patagonia, but don’t worry: he’s here to provide objective views on the industry’s best gear from all brands. Check out his Instagram to see where his adventures are taking him.

Review Policy: We do not accept payments or gifts from brands and vendors, and strive to provide unbiased, independent advice. Brands typically provide review samples which we return, and in some cases we purchase the item so we can keep using it long after the review. Affiliate Policy: We support the hours that go into our reviews and testing through affiliate commissions on purchases made through links in this article. These don't effect the outcome of our reviews or selection of gear, as per our Review Policy.