Platypus Hydration GravityWorks Water Filter
By Raymond Estrella
OWNER REVIEW

August 28, 2012

TESTER INFORMATION

NAME:	Raymond Estrella
EMAIL:	rayestrellaAThotmailDOTcom
AGE:	52
LOCATION:	North Western Minnesota, USA
GENDER:	M
HEIGHT:	6' 3' (1.91 m)
WEIGHT:	225 lb (102.00 kg)

I've been backpacking for over 30 years, all over California, Minnesota, and many western states. I hike year-round in all weather, and average 500+ miles (800+ km) per year. I make a point of using lightweight gear, and smaller volume packs. Doubting I can ever be truly ultralight, I try to be as light as I can yet still be comfortable. I start early and hike hard so as to enjoy the afternoons exploring/chilling. I usually take a freestanding tent and enjoy hot evening meals. If not hiking solo I am usually with my brother-in-law Dave or my twin children.

Water treatment is a sometimes annoying and always time-consuming process, but remains an absolutely essential part of any backcountry trip. In the hopes of delivering convenience with few sacrifices, the Platypus GravityWorks filter leverages, as the name suggests, gravity as a means to clean water. Nominal 1500L filter life is for clear water, turbidity will reduce the useful life of any filter. Maintain a high flow rate in the field by holding the clean water reservoir above the unfiltered reservoir.

The Product

Manufacturer: Cascade Designs Inc
Web site: www.platy.com
Product: GravityWorks water filter
Year manufactured: 2012
MSRP: US $109.95
Listed weight: 10.75 oz (305 g)
Actual total weight: 11 oz (312 g)
Storage sack weight: 1.1 oz (30 g)
Clean reservoir weight: 2.2 oz (62 g)
(In case it is used with smaller bottles.)
Dimensions listed: 3 x 10.75 in (7.6 x 27.3 cm)
Dimensions verified accurate

Quick & Dirty, Nitty Gritty

Esa620 electrical safety analyzer user manual. While not the most robust filter I have ever used, the Platypus Hydration GravityWorks is the easiest and fastest one I have ever owned. Putting out safe drinking water in well under a liter a minute the GravityWorks has become not only my main family filter but the one I take most often even on solo hikes. Its only hiccup comes when back-flushing, but that can be avoided by a little thought beforehand. Please read on for the details.

Product Description

The Platypus Hydration GravityWorks water filter (hereafter referred to as the GravityWorks or filter) is lightweight pump-free filter aimed at both weight conscious backpackers and groups. A re-design of Platypus's first gravity filter, the CleanStream the company uses the Hollow Fiber technology first seen in the MSR HyperFlow filter.
The way the technology works is like this. Think of a sealed-at-one-end glass straw with a bunch of little holes in it. As water is pushed against the side of the straw anything bigger than the holes is trapped outside while everything else passes into the straw and out the other end. In the case of the GravityWorks there are thousands of straws with hundreds of thousands of 2-micron holes to stop the bad stuff like Giardia and cryptosporidium that can be found in backcountry water sources.
Rather than use a pump to force the water past the filter the GravityWorks uses gravity to do the work. A 4 L BigZip bag clearly marked Dirty holds the suspect water. The dirty water reservoir has a quick disconnect that matches up to a silicone tube that goes to the inlet end of the grey filter cartridge. Both reservoirs have a thin nylon strap that allows them to be hung from a tree branch or rock knob.
At the outlet end filtered water goes through a clean tube to a clearly marked 4 L Clean reservoir. This one is reminiscent of the company's Hoser Hydration reservoirs in as much as it has just a small opening about the size of a pop bottle top. This will accept any type of Platypus cap or tube, and a clear Platy cap comes with the system.
A pressure clip on the clean tube allows the flow of water to be stopped at any time. The tubes end fits all Platypus containers so the GravityWorks can be used with any of their bottles or hydration systems should the big Clean reservoir be left behind to save weight.
A black drawstring with cord lock storage bag is provided to keep everything together. The bag is made of mesh on one side to facilitate drying. The whole works is not much bigger than a 1 L Nalgene bottle.
To clean the GravityWorks is pretty easy. Just fill the clean reservoir and then lift it above the dirty reservoir, while dropping the dirty reservoir down to ground level. If the dirty reservoir is allowed to run dry before lifting it above the clean one it will get air in the filter resulting in a horrible vapor-lock making it very difficult to back-flush. The trick is to do the reservoir position swap while there is still water flowing out of the dirty side of the filter. Now the water runs smooth and the pressure of the clean water back-flushes the cartridge, popping the stuff caught in the tiny holes back out and into the dirty reservoir. Now dump that water and the GravityWorks is ready to go again.

Field Data

I have used the Playpus GravityWorks on approximately a dozen two or three-day backpacking trips and two camping trips, all in Minnesota (MN). Locations have been along the Red River of the North near Hendrum and Halstad, Paul Bunyan, Two Inlets and Smokey Hills State Forests, Chippewa National Forest, Lake Bronson and Old Mill State Parks and on the Superior Hiking Trail along the Beaver River. Temperatures have ranged from lows of 34 F (1 C) to highs of 88 F (31 C) in conditions from sunny, hot and humid to stormy and raining. It has held clear eastern MN river water, not-so clear central MN lake water, and absolutely filthy western MN river water.
The picture above was taken at McCarty Lakes in Paul Bunyan State Forest and the one below was taken along the South Fork of Two Rivers in Lake Bronson State Park.

Observations

I have to thank Cascade Designs for introducing me to gravity systems. April of 2009 I bought their first system, the CleanStream. After my first trip with it I was hooked as were the people I hiked with that I let use it to save time. I never got around to reviewing it as I spent over a year helping another author work on a huge water treatment article that saw me using 11 different systems. When I rea

Patypus Water Filtration System Users Manual