Hands-on Gear Review

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Platypus GravityWorks Review

   
Editors' Choice Award

Backpacking Water Treatment

  • Currently 4.7/5
Overall avg rating 4.7 of 5 based on 10 reviews. Most recent review: August 25, 2014
Street Price:   Varies from $80 - $110 | Compare prices at 7 resellers
Pros:  Fastest treatment time, easy to use, lightweight, requires little maintenance, can treat and store up to 8L
Cons:  No separate storage for clean and dirty hoses, expensive, hard to collect water from small or non-flowing sources
Best Uses:  Backpacking, group camping, backcountry trips with a basecamp, car camping
User Rating:     
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 (4.6 of 5) based on 9 reviews
Recommendations:  100% of reviewers (8/8) recommend this product
Manufacturer:   Platypus
Review by: McKenzie Long ⋅ Senior Review Editor, OutdoorGearLab ⋅ August 25, 2014  
Overview
After some surprising results in our tests, the GravityWorks took the lead in our comparison, winning the Editors' Choice award. We initially thought this system would be bulky and time-consuming, but the opposite was true. In fact, this is the fastest system for filtering water, it is the best option for filtering large quantities, is one of our lightest filter systems, and requires little to no maintenance. The filter lasts a long time before replacement (1,500 liters), being beaten only by the MSR MiniWorks EX (2,000 liters), Sawyer Mini (100,00 gallons) and Sawyer Squeeze (claimed 1 million gallons). Since it easily treats small or large amounts of water, it is the most versatile system, working well for a camp of multiple people or for a solitary hiker on the move in the mountains. The primary drawback to this system is that is more expensive than the average pump filter such as the Katadyn Hiker Pro or the MSR Sweetwater Microfilter. Also, it does not treat viruses like the SteriPEN Adventurer Opti or the First Need XL, so if you plan to travel around some very sketchy water, this may not be the filter system of choice.

This filter just barely beat out its closest competitor, the MSR AutoFlow Gravity Filter. This very similar system may work best for you, especially if you already have an MSR hydration bladder or Dromendary bag to use with it.

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OutdoorGearLab Editors' Hands-on Review

The GravityWorks is a unique water purification solution in that it combines filtering with storage. It comes in either a 2L size or a 4L size, and the 4L system provides a total of an 8-liter capacity (4L in the dirty bag and 4L in the clean bag). This makes for a convenient and ample water supply for your campsite or for backpackers hiking through a zone with scarce water sources. This means you can eliminate the need to carry a separate water container for campsite water, saving weight and space. In practice, it is fast, easy to use, and makes treated water easy to access whether you are solo backpacking or in a group campsite.

Performance Comparison
Click to enlarge
Luke Lydiard using the GravityWorks to rehydrate after coming down from Clyde Minaret in the Ritter Range. The whole system works surprisingly fast, so is useful even for hikers on the go.
Credit: McKenzie Long

Reliability/Effectiveness
The hollow fiber filter is effective against protozoa and bacteria, but not viruses. For what it does sterilize, this is a very reliable system. It is ideal for backpacking in North America where Giardia is the biggest concern, but would not be the best option for international travel.

The absence of moving or electronic parts means that it is less likely to break or malfunction. Be cautious of letting the filter itself freeze. This could potentially ruin the filter without the user realizing it. We protected against this by tucking the filter element in our sleeping bag on nights we were worried the temps would get below freezing.

Ease of Use
This system is ridiculously easy to use, even more so than a lot of pump systems. You fill the dirty bag, zip the top, attach the hoses with the arrow on the filter pointing towards the clean bag, and set the dirty bag somewhere above the clean bag (it doesn't even have to be very high). This system worked fine with the dirty bag sitting on a rock and the clean bag on the ground, it does not need to be hanging from a tree to operate. However, the 2L system includes a buckle strap (the 4L system has a solid strap) and the buckle makes hanging the dirty bag from a tree especially easy.

After you fill it and set it up, you can let it work its magic while you set up camp or eat a snack. We like that the dirty bag and clean bag are clearly labeled, and the dirty bag has an open zippered top, while the clean bag does not, so you will not accidentally mix them up and cross contaminate. The only downside is that the hoses are not as easy to keep separate. Since the dirty hose has the filter attached to it, they are easy to tell apart, but there is no convenient way to pack them to keep the hoses separated from each other.

Click to enlarge
Scooping water into the GravityWorks. Unless the source is a really small puddle, this filter is the easiest to use and the fastest working filter.
Credit: Luke Lydiard

Our main complaint is that the top can be incredibly difficult to zip shut, especially if your hands are cold from dipping the bag into a snowmelt stream. In our experience, this zipper gets harder to close the longer you own the filter. It closes like a ziplock bag but with a much larger and harder plastic seal. It can require some serious hand strength to zip shut so that it won't leak.

Click to enlarge
The most difficult part of using this filter is zipping the top shut, which becomes more difficult the longer you own this system and is especially difficult in the cold.
Credit: Luke Lydiard

Treatment Capacity
This filter excels at treating large quantities of water for groups or cooking. The 4L system can store and carry up to eight liters of water at a time, and the whole system can treat an entire gallon in under five minutes. It works very well to set up this system at camp and take water from it as you need it.

Time Before Drinking
At first, we were skeptical of this system. We thought it would be slow and cumbersome to use, but instead we were quite impressed. This gravity system works surprisingly fast. We timed the filtration process in both the 4L and 2L systems. We tried to make it as even as possible by raising the dirty bag so that the hose fell straight to the clean bag with no coil of hose on the ground, making the fall line the same for the tests. It took 1:50 for the entire 2L system to work and 3:05 for the 4L system. We also timed just a single liter moving through the filter, and that took exactly one minute.

This is less time than waiting for tablets to work their magic, and involves less work for the user than any of the pump systems. None of the pumps will provide four liters of treated water in under five minutes. Even the SteriPEN, which is one of the fastest systems, takes 90 seconds per liter. If you do the math, takes six minutes to purify four liters of water, not counting fill times in between sterilizations. Waiting almost five minutes to drink can seem like a pain, but in actuality this GravityWorks system treats the most water the quickest and with the least amount of work.

Click to enlarge
Water flowing from the dirty bag of the GravityWorks with Clyde Minaret in the background. It takes 4 min 50 seconds for this system to filter an entire gallon, which is faster than all of the pump systems, and even the SteriPen for this volume.
Credit: McKenzie Long

Weight
Including the storage bag, the 4L system weighs 11.99 ounces, which is one of the lightest filters we tested, being beaten only by the MSR Hyperflow Microfilter, the Sawyer Squeeze, and compact straw systems like the LifeStraw and the Sawyer Mini. This makes the GravityWorks a great choice for hiking and backpacking since it does not weigh you down.

Durability/Uses Before Maintenance
The maintenance on this system is very low. The filter is good for 1,500 liters, which is second only to the MSR Miniworks ceramic filter and the Sawyer Squeeze, which are good for 2,000 liters and 1 million gallons respectively. So the Platypus filter does not need to be replaced all that often. In the meantime, the only other maintenance required is a quick and painless back-flush when you set up the gravity system. All this requires is elevating the clean bag above the dirty bag for a couple seconds to let air bubbles escape, which is nothing compared to scraping a ceramic filter or reversing all the valves to set up the complicated back-flush on the MSR Hyperflow.

Click to enlarge
The GravityWorks system is simple and low maintenance. The arrow on the filter shows the direction of flow, and it lasts for 1,500 liters.
Credit: McKenzie Long

There are two things to watch out for: do not puncture a hole in one of the bags, which would ruin the system, and don't let the filter unit freeze, which can damage the hollow fiber membrane. However, the bags seem very durable and in our long-term tests where we have used this filter extensively, we have not had an issue with this. It is possible that the MSR AutoFlow Gravity Filter would be more durable, since the bag in that system is made from the tried and true drom bag material found on the MSR Dromlite, but we have found the Platypus bags to hold up to a lot of hard use.

Taste
The water flavor remains unchanged and particulate is strained out of the clean water. We find the water through this system to be fresh and delicious.

Differences in the 4L and 2L Systems
Both the 4L and 2L systems use the same filter and draw from the same general principle for using gravity to push the water through the filter. They both feature bags made of durable Platypus plastic and come with a shut-off clamp for the hose. So is the only thing different the size? No. Actually there are a couple of notable differences, mainly in the configuration of the system. Here we list them out for you so you can better decide which one will work best for you.

The 2L system set up with the 4L bag on the right for comparison.
The 2L system set up with the 4L bag on the right for comparison.
Credit: Luke Lydiard

4L System:
  • $120
  • 8 liter capacity
  • weighs 11.99 ounces
  • hose screws onto an opening in the clean bag
  • filter hose attachment is on the center of the dirty bag, and out of the way
  • no water bottle adapter

Click to enlarge
2L vs. 4L reservoir systems. The 2L package allows for a total of 4 liters of water storage, and the 4L package can hold 8 liters of water. Notice the different locations of the hose attachments.
Credit: Luke Lydiard

2L System:
  • comes in Complete Kit ($110) or Bottle Kit ($100) options
  • can be used in 3 configurations: direct to water bottle, direct to a hydration bladder (without removing it from your pack) and direct to its own system (Complete Kit only).
  • 4 liter capacity
  • weighs 11.5 ounces for Complete Kit with bottle adapters and 9.5 ounces for Bottle Kit without second bag
  • hose attaches to clean bag water bottle cap with a rubber suction cup
  • clean bag is a Platypus soft bottle (can stand up on its own)
  • filter hose attachment is on the side of the dirty bag, and and sticks out slightly
  • includes water bottle adapter for push/pull bottle caps
  • also includes wide-mouth bottle adapter

Click to enlarge
The suction cup push/pull cap adapter that comes with the 2L GravityWorks system.
Credit: Luke Lydiard

Best Applications
Since this system excels at treating larger quantities of water, it is well-suited to car camping or backcountry trips that will involve a base camp. Our initial impression was that it would not be as conducive to fast in-a-day backcountry missions where you want smaller quantities of water quicker, and do not want to sit around for five minutes waiting for it to filter. Then we tried it on our own hiking mission and felt that it took only as much, if not less, time to filter water through this system as with a pump. Even though the bags hold a gallon of water, you can fill the system just part way if you are in a hurry and do not want to carry extra water. Our final verdict: it works well in just about any backcountry situation where you would like to filter water, with perhaps the exception of really nasty shallow pools where scooping up goopy water would be difficult.

Value
At $120, the 4L filter system is on the expensive side, which seems strange for such a simple system. It costs more than even the SteriPEN with its high-tech UV light. It does, however, include storage bags, which could cut your costs on another item. This system is excellent to use and works very fast, so in our opinion it is worth the investment, but expect to shell out a few more dollars for the luxury that the gravity system provides.

All it takes for this filter to work is for the dirty bag to be elevat...
All it takes for this filter to work is for the dirty bag to be elevated over the clean bag. This can consist of sitting on a rock, hanging from a tree, or even just holding up the bag.
Credit: Luke Lydiard

Conclusion
In the end, we felt that the GravityWorks was the best water treatment system available, and the one we'd recommend to friends and family for general use. If you are looking for one water filter that can serve your needs, whether car camping or backpacking, this is the one we'd pick. And, that's why it earned our Editors' Choice Award for best water filter.

Click to enlarge
Scooping out water to treat with the GravityWorks.
Credit: Luke Lydiard
Other Versions & Accessories
You can purchase this versatile filter in either 4L or 2L sizes. For lighter weight get the small version, for more versatility and group camping get the larger version. Here is a list of some of the other versions and extra accessories you can purchase to complement your filter system:

The GravityWorks 2.0L Bottle Kit, $100, filters into your own bottle, holds up to four liters of water and is ideal for 1-4 people.

The GravityWorks 2.0L Reservoir Kit retails for $20, while the GravityWorks 4.0L Reservoir Kit retails for $55 - both can be used to replace worn out or damaged reservoirs.

The GravityWorks 2.0L Replacement Hose Kit, $18, comes with a clean and dirty hose, as well as a replacement fitting and shutoff clamp. This replacement kit is also available for the 4 liter version.

The GravityWorks Carbon Element retails for $13 and helps to remove odors, flavors, and various other compounds.

The GravityWorks Universal Bottle Adapter, $13, eliminates the need for a dedicated clean water reservoir, as you can filter directly into various bottles or hydration systems.

McKenzie Long

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OutdoorGearLab Member Reviews


Most recent review: August 25, 2014
Summary of All Ratings

OutdoorGearLab Editors' Rating:   
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 (5.0)
Average Customer Rating:   
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 (4.6)

100% of 8 reviewers recommend it
Rating Distribution
9 Total Ratings
5 star: 67%  (6)
4 star: 33%  (3)
3 star: 0%  (0)
2 star: 0%  (0)
1 star: 0%  (0)
Sort 9 member reviews by: Most Recent | Most Helpful
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   Aug 16, 2014 - 01:17am
Fletcher · Climber · Altadena, CA
I've been looking for a while for a replacement for my old pump filter.

I got the GravityWorks after the very positive review here on Outdoor Gear Lab and I have to say it's really exceed my expectations. This is the filter I've been looking for what seems like day one. But it's something I'd never have envisioned.

Out of the box, it was way, way lighter and more compact than expected. And it is FAST. I used it on a weekend backpacking trip with my son and water filtering was fun! I probably used much more water than I normally would have because the GravityWorks largely eliminated the hassles of filtering.

I have a 4 liter Platypus collapsible bag and it worked really well with this container for bringing a lot of water back to my camp (which was on a ridge above a lake).

The components are well labelled so you know what's clean and what's dirty. And the mesh carrying bag includes a label with reminder instructions for back-flushing, which is a good idea to do to keep it in good working order.

The one tricky part is filling the "dirty" bag. I could get it about half full and then the water pressure of submerging would close down the remaining open part and I'd have to try again. This caused me to stir up some sediment but the bag still remained pretty clear of that somehow. I finally did get it to fill with a pulling motion and holding the opening with my hand wide. Having a cup to fill would be a good extra to have, especially in a shallow water source. Maybe with practice this will get easier.

Because of the freezing issues, I"m not sure how good this would be for winter use, though I would more likely be melting snow in that situation. And dunking the dirty bag in cold temperatures (hands and all) is not particularly appetizing.

But overall, I couldn't be more delighted! Once of the best purchases I've made in years! Well worth the price ($99 at REI).

Bottom Line: Yes, I would recommend this product to a friend.
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   Apr 30, 2014 - 01:55pm
Platy Hydration · Climber · Seattle
Hello! We at Platy would like to answer some of the questions mentioned in the reviews.
You can filter directly into any hydration system (not just Platy) using our Universal or Push/Pull Adapter. The Universal is included with 2L systems. Both can be purchased separately.
We are currently working on a new bag opening that will allow better water collection from small streams. When water sources are really small and non-moving we use a cup to transfer water to the Dirty reservoir.
Freezing and hard drops are a concern for all hollow fiber filters currently on the market. In the case of freezing, ice crystals forming inside the filter can rupture the hollow fibers. Our instruction manual includes an easy field test that will determine if your filter has been compromised. The best way to prevent freezing is to bring the filter into your tent at night.
Thanks to everyone who purchased and reviewed the GravityWorks!

Bottom Line: Yes, I would recommend this product to a friend.
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   Mar 1, 2014 - 10:43pm
C.Houston · Backpacker · Greenwich, CT
Admittedly, I've never used a pump, but compared to a steri pen, this is far easier if filling anything more than a single nalgene. My initial understanding was that you could filter directly into the drink tube of a Platypus hydration system, but I haven't been able to do this due to tube and fitting sizes. Instead, it seams you have to fill the clean bag and can from that fill a hydration system through the drink tube.

Bottom Line: Yes, I would recommend this product to a friend.
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   Feb 11, 2014 - 11:34pm
Fair-In-Height · Backpacker · Portland, Oregon
Four of us went camping in the Three Sisters wilderness last fall for 4 nights. We took two filters along, the GravityWorks and a pump filter. I don't know what brand the other filter was because it never showed itself. We had unending filtered water. What an absolutely amazing filter. At the end of the trip we rated the various peices of equipment we brought along. The Platypus GavityWorks was rated by all of us as the #1 best peice of equipment we brought.

I found out that one of the guys bought a GravityWorks filter for himself a week later.

Bottom line… I give it 5 stars.

Bottom Line: Yes, I would recommend this product to a friend.
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   Jan 7, 2014 - 04:04pm
WhiteTomato · Hiker
Used this over a four-day trip to Saguaro National Park.

The filter is as simple and fast as described. It filtered four liters of water within minutes with little hassle.

My main reason for not giving it four stars would be the slight frustration with gathering water. I had a small spring that had gathered in a pool, so I had water flowing into the source but not moving out quickly. I had to scoop water. I tried submerging the entire bag a few times and that didn't fill it any quicker. I basically had to scoop water every time and multiple times. I would have preferred if it would have worked by submerging it so that I didn't stir up as much debris as I did in a shallower pool on my first attempt. It might be a bit easier if the opening was a wider. Also--and I readily admit this might be user error--I could never quite get to four liters of water. Whenever I attempted to seal the bag to travel back to my camp site, water squirted out. I'm sure with time I could figure this out, but the seal--a ziploc type seal--wasn't that easy to secure, although once done, it didn't come undone. It would also be nice if the line for carrying the bag was longer. I had a little trouble climbing over rocks with the bag.

It is a bit bulky also so if size is an issue, this may push some people away, but it is also light. Although the Outdoor Gear Lab review mentions no separation of clean and dirty hoses, the directions specifically state NOT to detach the hoses while using them/on a trip. Also, the hoses are different lengths so its easy to know which is which.

In response to a below-review, water did freeze in the bag and hoses overnight. It did not affect use of the filter after it melted and the instruction manual makes no mention of adverse effects from this happening.

Bottom Line: Yes, I would recommend this product to a friend.
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May 7, 2013 - 06:10pm
 
harpo · Climber · South Lake Tahoe
I just got the MSR Autoflow gravity filter, which I am pretty sure uses the same filter element as the Platypus GravityWorks. The MSR directions says you have to be careful not to freeze the filter element. Do you have to take the same precautions with the Platypus? What does it say in the directions? Anyone have problems with the Platypus or the MSR freezing in the feild?
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   May 6, 2013 - 12:18am
silveriec · Mountain Biker · VT
I have only used this as a guest project assistant for a Great Basin Institute trail crew. The trail crew was along a fairly large river in a canyon just outside Reno where the water was very churned up from snowmelt (it was late June). Their feedback as a group in the mid-day heat was that they were drinking so much and having to refill it often--- was that the filter replacement cost was going to be a concern for them that season. They also were trying to be careful to not puncture the bags as they were using them so regularly.

Bottom Line: Yes, I would recommend this product to a friend.
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   Sep 10, 2012 - 01:54am
ole'Eagle · Backpacker · Oregon-California
Our group of six used this over our eight days from Isberg Pass Trailhead to Happy Isle, YoValley (August 2012), with three nights at Lyle Fork of the Merced River under Mount Ansel Adams. Worked incredibly well--water detail no-longer a serious burden. Hang it on a tree, walk-off, comeback, you have water!!! Was skeptical even after testing at home, but entrail and in camp it worked flawlessly. Four stars (fishermen always leave the limit short one for the BIG one) leaving room for the next evolution :-) !! ~~ole'Eagle'Paul

Bottom Line: Yes, I would recommend this product to a friend.
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   Jul 26, 2012 - 12:29am
spidey · Climber · Berkeley CA
Used it on the JMT last year and it worked great! way easier and faster than a pump filter.

Bottom Line: Yes, I would recommend this product to a friend.
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GravityWorks
Credit: Platypus
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