Be prepared.

You're leading a field camp this summer and the last thing you want to do is take care of a bunch of college kids with giardia. You have the GravityWorks filtration system, but could do with a bit more capacity, so you've grabbed the Platypus GravityWorks 4.0L Replacement Reservoir Kit. Your previous dirty reservoir was getting a bit grungy, so you get to start over with a brand-spanking-new bag, and now you can store an additional four liters of fresh clean waters for your thirsty undergrads. While this kit does not include the actual filter and filtration tube, these replacement reservoirs come in handy when you need additional capacity or a couple backups—just in case.

  • Replacement reservoirs for Platypus GravityWorks filtration system
  • Dual-layer laminate provides food-grade, taste-free interior
  • 8 liter total capacity supplies backpacking groups with clean water
  • Disconnect fittings interchangeable with any GravityWorks system
  • Reviews
  • Q & A

Started strong...

  • Familiarity: I've used it several times

I purchased this filter about a year ago for a trip that I was doing with a group of friends. Instead of carrying multiple filters that took time to pump, I figured this gravity fed 4L would fit the bill. Which it did, for one trip.

To start, the system worked flawlessly. Over the 3 days of usage on my first trip with it, the water filtered quickly and it was nice to be able to keep 4L of clean water hanging up where we setup camp.

The second trip I used it on, the filter continued to flow fast and drinkable water was available in no time. However, I noticed stretching where the nylon straps go through the reservoir bag. They attempted to beef up the construction of the holes the strap passes through, but after just several days of use, it looked close to stretching to the point of failure.

Fast forward almost a year...I just recently got back from a week long trip in Zion and Bryce. We did the top down hike of the narrows and on my very first night, the filter failed. I filled the 4L reservoir up and the water barely trickled through the filter. It was unfortunately the only filter I had (shame on me for checking all my gear but the filter!) and ended up boiling water for use that night. I hung up the 4L and over the next 7 hours, it finally filtered. But at the rate of about 1/2L an hour, it’s basically useles. And by now the nylon strap handles are a hair away from ripping through the reservoir bag.

I’m summation, 3 trips and maybe 10 gallons of water later, this system has failed. The only reason I gave it 2 stars was because it worked so well the first couple of uses. With a few tweaks, this could be a fantastic system, but as it now it just doesn’t hold up.