The bladders are made of heavy plastic and are very durable. It takes up a little more space than I would like – roughly the size of a water bottle. The bladders can be wrapped around the filter for packing. The system is easy to set up and breakdown. The higher your “dirty” bag is from your “clean” bag, the faster the water will filter. Hold/place the “dirty” bag higher than the “clean” bag and let gravity do the work! Gravity will pull the water through the tube, through the filter, and into the “clean” bag. The bladders are so thin, this can be from a very shallow stagnant pool – more so than you could with a water bottle. Then fill the “dirty” bag with the dirty/unfiltered water. Before filling the “dirty” bag, set up the system by connecting the tubes to the water filter and to each bag (instructions are included). There are two 4Liter bladders very clearly and in large font labeled “clean” and “dirty”. This is one of the best things about this water filter. It doesn’t kill viruses, but it does get most of what’s commonly found in the backcountry. It meets all EPA & NSF guidelines for the removal of 99.9999% of bacteria and 99.9% of protozoa. Protozoa, bacteria, and particulates from water before you drink. Most easily, you can order it from Amazon or REI or straight from Platypus. It’s available at any outdoor sporting good store. You might be lucky to find a sale an get it for $90. The Platypus GravityWorks Water Filter is going to cost you around $100 wherever you go. Takes up a fair amount of space for its size.

Lays flat and can fill from shallow water.No need to pump water, let gravity do the work!.Come back a few mins later and you’ll have liters of nice clean water. I especially love that you can set it up, forget it and let it do it’s work. It’s super easy to use, versatile, lightweight, and very effective.

Fill one bag with the dirty water, let gravity pull it through the tube and filter, and then you get clean water in the second bag. This filtration system is characterized by two 4Liter (or 6L or 2L depending on which you get) plastic bladders connected by a hose which goes through a filter. Treating your water is is crucial when in the backcountry and it’s important to choose the system that’s the best for you. But it’s not a completely perfect system, so this will still be an objective review. It saved our butts on our last desert backpacking trip. I love the Platypus GravityWorks 4L Water Filter! So much so that I decided to write a review about it.

Platypus water filter