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What are the differences between gravity water filters?

What are the main differences/pro cons of the Platypus gravity system and the Katadyn BeFree Gravity 3L?  Is there one more superior than the other?  Is it better to have the 8L total capacity option?

4 Replies

@Krycol08 Thanks for reaching out!

All hollow fiber gravity filtration units work basically the same way, which is to say that you're going to get the same level of filtration from each of these filters. The main difference is going to be the inclusion of the second bag in the Platypus system as well as getting about 50% more life out of the filter (1000 liters for the Katadyn, 1500 for the Platypus). Additionally, the Platypus gravity system uses a back flushing technique to clean the filter, the Katadyn simply requires you to shake it through water to clear debris.

In terms of the capacity, that really is going to depend on what kinds of conditions you are using the filter in. I own the MSR Trail Base Gravity Water Filter System and I appreciate how versatile it is. Because the water filters quickly, it is easy to continue to filter more water as the system empties. Perhaps, if you were in an area where water re-supplies were few and far between and you needed a way to carry more water at one time, there would be a reason for needing more space. Or if you were using it at a base camp and there were a lot of people using one filter it could be advantageous to have a larger amount of water.

Hope this helps, let us know if you have any other questions!

At REI, we believe time outside is fundamental to a life well lived.

if you're backpacking, I wouldn't think you would need to carry an 8L capacity!

IMO 4 liters is the max you would ever need, meaning for 1 overnight camp 4L takes you through at least a dinner and a breakfast, plus leaving you with a liter when starting the next days hike.

And if you need more, just refill and filter.

REI Member Since 1979

That is generally the case but in 100 degree heat in "desert" conditions you need 1-2L an hour so if you are crossing a long desert section with no water sources 8L may not be enough.  It all depends where the next reliable water source is and how fast and far you hike. 

However unless it is for group use you don't really need a filter system that has an 8L capacity.  I would split it up between 1L bottles and 2L bladders/collapsible bottles. 

For more typical trips I agree 4L capacity is adequate and generally it is not necessary to carry more than 2L unless you want to dry camp that night.

The 4L Gravity Works is really intended for group use.  I have one and personally I had bad luck with it.  It clogged up after a couple of uses.  Replacement filters are expensive.  It's also a bit heavy at 11.5oz.  I have also used the Katadyn hiker and had good luck with that...sometimes it is convenient to pump the water...but it is also a bit heavy at 11oz without any storage capacity but it does have a carbon element in its filter which can remove chemical tastes...good if you travel though areas that might have agricultural run off.

I now mostly use a Sawyer Squeeze which can be used is various ways but I use with a 2L CNOC VECTO bladder (~6oz combined) and two 1L Smart Water bottles in gravity mode and encourage everyone to bring their own filter rather than relying on one "group" filtering system.  Generally I carry drops/tables as backup and generally a stove/pot.

I use a 2 L gray collapsible bag I fill from the water source, usually a stream. I attach to that a sawyer lifestraw, and aim the stream into a collapsible 3 L bag that U use only for filtered water. The only water I carry while backpacking is in a 1 L Platypus bladder. I can always use the life straw to filter more water. The only time I carry more than a bladder of water is when I KNOW I will be passing through a dry stretch with no stream or springs. Most of my backpacking is solo so I am filtering water only for myself.

aka "Boonerelli"

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