Platypus GravityWorks Filter Review – 4.0L Water Filtration System

[Josh Belcher]

Companion forum thread to: Platypus GravityWorks Filter Review – 4.0L Water Filtration System

This Platypus Gravity Works filter review focuses on the key strength of the system: high treatment capacity for relative ease.

[Philip Tschersich]

“I’ve only used the system once in the field…”

How can you review a product you have only used once in a real-world scenario? I don’t mean to sound harsh, but it seems like a somewhat premature review. You tested it in April of 2016. Didn’t you have time to use it more after that?

I have the 2-Liter system, and a friend has the 4-liter. We used his extensively this summer as the main filtering system for groups of up to 5 people, and it worked well for the most part, though the filter became progressively more sluggish in filtering over the course of the season despite regular back-flushes and generally finding relatively clean water sources. I wonder if using a Sawyer-style syringe might clear the filter better than the rather passive back-flush method Platypus suggests. My 2-liter system was defective out of the box with the ‘dirty’ reservoir having it’s welded seam too close to the bag’s edge and the side blew out on the first use.

It’s easy to populate the “pros” list on a new product, but it’s only possible to enumerate the real “cons” after extensive and heavy use in my opinion.

[Bruce Tolley]

Josh, Nice review of the 4 liter system.

I have used both the 4 liter and the 2 liter system. There is a 2 liter option without the second bottle that comes in at 9 plus ounces that comes with a bottle adapter and gives you the option of filling any bottle you want or already own.  I think the main plus of the GravityWorks is that it is VERY fast. If you need water for a group of 2 or more people (esp if they notice the taste of chorine dioxide), it is the way to go. If you are base camping, even more so.

I have also encountered the clogging issue Phillip mentions when taking water out of Sierra Nevada lakes in the late season. I suspect biofilms growing on the surface were clogging up the hollow fiber filter. No amount of back flushing fixed the problem. But I have had the same issue with pump filters which you can sometimes fix in the field.

Platypus does warn against dropping or allowing the filter to freeze which applies to Sawyer filters as well.

[Michael Ciofalo]

Hello Josh,

Thank you for the comprehensive review!

I utilized a similar setup last year on a 23 day trek through the Sierras. There are a number on configurations that this filter-tube-bag assembly can be used in and mine was a dirty bag with the filter inline to a drinking tube – worked like a charm. These types of filters do get sluggish and I found that filling a second platty with filtered water and forcing (squeezing) it through the filter in reverse (backwashing) worked well. I would also squeeze the dirty bag to fill my cooking pot quicker – man did I get hungry and couldn’t get some meals done quick enough!

None of the equipment failed (I’ve put an additional 20 days on it do date) and I would highly recommend this product for the following reasons:

Ease of use, application flexibility, reliability, durability, and cost.

Happy trails!

Mike

[Alice Hengst]

I’d like to see a comparison with the new Katadyn gravity filter which I have been using. The Katadyn does not have a “clean bag” but has connections for one. Also, the Katadyn has a great flow rate, which makes filling containers straight from the hose very convenient. I would imagine it might be hard to find a hanging arrangement for both the dirty and clean bag with the Platyplus system where you didn’t need to hold the clean bag while it fills, especially above tree line.  I think the zip bag system of the Platy might be nicer than the folding system of the Katadyn.

[Daniel Lee]

I have used the 4L version many times with my scout troop and concur with the review as well as comments above.  I have been pondering a 2L version for my personal trips.  Does anyone have experience with replacing the rather large Platy filter with the smaller Sawyer mini?  I’ve read a mixed bag of comments but no real solid evidence that this works well.  (There also appear to be a couple of different Sawyer minis on the market.)  My thoughts would be to leave the dirty bag at home and replace the Platy filter with the smaller/lighter mini.  I’m not a SUL/UL backpacker but always looking to eliminate unnecessary weight.  Appreciate any thoughts…   -dgl

[Josh Belcher]

I can agree that one use in the field doesn’t constitute a tried-and-true evaluation of a product.  Since then I have used it on a 75 mile AT- Great Smoky Mountains thru-hike and a 27 mile Pinhoti Trail hike (Didn’t hike during the summer months).  I did find in the Smoky’s that the filtering rate decreased and without having the “Clean Bag” in my kit it made it almost impossible to backflush. I have now a 10mL syringe to force flush the filter if it becomes slower and that seems to have helped.  One thing that I’ve found is that I don’t need as much water for individual use as I thought I did. I changed from my 2.5 L bladder and tube setup to carrying two 1 L SmartWater bottles and that makes my water supply last longer. This will likely warrant trying a system like the Sawyer Squeeze or Mini in the future.  However, I do like the convenience of this system as compared to the squeeze type. The dirty water zip-lock fill and the gravity distribution seem much easier than the other systems (as compared to watching my fellow hikers around the water source).  For individual use the weight (approx 4 oz savings) and affordable price may lead me to use a Sawyer Squeeze for individual use and save the Platypus 4.0 L for group adventures or when I take my kids on the trail.  I definitely consider the Platypus a winner for multiple people and for in-camp use filling cook pots, cleaning, and topping off bottles before hitting the trail again.

Thanks for the comments!

[James Marco]

Good review. On a trip two springs ago (around a year and three quarters) I finished my hike early and hung out at a lean-to for 3 days waiting for my ride. A group of 4 guys came in on week long fishing trip with one of these 4Liter filters (a couple guys came in the next day for a total of 6 in their group.) For the group, it performed really well. Considering the 12oz weight distributed over 6 people, it was about not quite half the weight of my Steripen. They used it extensively over the time I was there (their only clean water supply) and actually used one of the water bladders as a 2nd “dirty” water bag so they didn’t have to go down to the stream so often. I mentioned that they needed to keep the filter from freezing, and they disconnected it each time and put it by the fire as they went out fishing or in one of the sleeping bags at night. (Yup, 30’s-40’s during the day, teens-20’s at night. They had more problems with canisters in the morning than with the water.)

Anyway, the flow rates were very good over the time that I was with them, just a few minutes that emptied the dirty water into the clean bag. I also mentioned that a higher drop would increase the flow regardless of the position of the filter in a closed system, so they tried it…it worked and may have contributed to the fast flow rates for the three days I was there. One tied to the top of the lean-to and the other at the limit of the tube. Anyway, I usually don’t care for a filter system, way too fiddly for my (usually) solo needs, but was impressed how the system worked for volume their group used.

[Joe Lynch]

My scout troop has used one for trips over the past 5 years for sporadic weekend and 5 day trips over that time mostly in the Sierras. We had one bag holed by a branch when carried outside of a pack but otherwise no issues. Back flushing the filter on trips worked fine for us given that we cleaned the filter after each trip. However, our longest trip was 5 days so your mileage may vary. We used mostly clear water sources with it. Very nice piece of kit. I’m considering getting one for my personal use with smaller bags.

[Hank Kaplan]

A better back flush for the Sawyer filter is to use a catheter syringe instead of the Leur Lok tip syringe that comes with the Sawyer.  Not familiar with the Platy filter but cutting the catheter tip to fit over the Sawyer output (not inside like the Leur Lok tip) gives a much better fit to really clean out the filter.  The tighter fit locks onto the filter and supports the filter so you can backflush by just holding the syringe, although you may want to support the filter as well.  A “slip tip” syringe may work as well but catheter was what I had and it worked.  From what I could see in the Platy site photos it (or a variation) should work on the Platy filter as well.

[Chris B]

Nice summary Josh.

I have also been using one of these with our Scout Troop and for my own personal use and do have a couple of reservations.

The original filter I had lasted for years with plenty of use and I was very happy with it. The problems started when I had to replace the filter after a trip where the only water source was somewhat green to say the least, I expected to have to replace the filter after this so no problem there. I noticed that the replacement filter was a different design to to original one but thought nothing of it until it blocked on the first trip even though I backwashed after every use. I got home and replaced the filter again and this one also clogged after very little use. The mode of failure appeared to be different with the new filter, the older filter would suffer reduced flow but would always recover after a good backwash, on the other-hand the newer filters seem to totally block and won’t backwash even with a syringe. A bit of a bummer if you don’t have a backup.

Most of the use has been in the Sierra Nevada with clean water with minimal sediment so I was very surprised to experience clogging with so little use.

What I did to fix it was replace the filter with element with the one from my Sawyer Squeeze (full size not Mini) and it has worked just fine plus the option to use the syringe to perform a forced backwash is useful.

This hybrid Sawyer-Pus configuration combines the easy to fill Platypus bags with a reliable Sawyer filter that works for me.

A common situation that occurs with the Gravityworks that can dramatically reduce flow are air bubbles in the pipe. To fix this problem backwash as soon as you have enough water in the clean bag to do so. Just hold up the clean bag until all the bubbles have bubbled up into the dirty bag and lower it again to resume full flow filtering.

If you go the Gravityworks as you only filter either take a spare filter element or pack some chlorine dioxide tables.

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