A Review of the Platypus Gravityworks Water Filtration System


The other day I got a change to test a Platypus Gravityworks pump free water system.  It is a simple almost foolproof system.  It consists of two well made plastic bags one marked clean, the other dirty, the filter and two hoses.  One hose connects to the clean water bag, the other to the dirty bag.  It is impossible to connect the wrong hose to a bag.  The fittings are different.  The only place you could make a mistake is to install the filter the wrong way around.  But even this would be hard to do; the filter is well marked with the direction of water flow.  Another difference between this system and most others is that it is packed in its sack fully assembled.

You fill the dirty water bag and hang it up above the clean bag.    There is a clamp on the hose between the filter and the clean bag.  When you release this clamp the water will start to flow.  The specifications state that it will filter four litters in two and a half minutes.

Filling dirty water bag

I took the filter to the nastiest pond that I know off and filled the dirty bag.  The water was badly discolored and smelled awful.  The water was run through the filter.  It came out clean and without an odor.  The water was quiet drinkable.  I downed a cup of it with no bad effects.


  • Effective against protozoa Yes
  • Effective against bacteria Yes
  • Effective against viruses No
  • Effective against particulate Yes
  • Effective against chemicals/toxins No
  • Weight10.75 oz / 304.75 g
  • Width3 in / 8 cmLength9.5 in / 24 cm
  • Filter media Hollow Fiber
  • Filter pore size.2 microns
  • Flow (L/min)1.75 liters per min
  • Cartridge life1501 liters
  • Field cleanable Yes
The water

When you pack the system away after use, be sure and follow the storage directions.  You need to rinse the filter out with a chlorine solution.

Water flowing from dirty bag to clean one


I found this system easy to use, love how fast it is.  No pumping is required.  It takes very little room in my pack.  On a scale of 1-10 I would give this system a nine and a half.


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