Gravity Water Filter

Usually when I go hiking I take along my portable Katadyn Guide water pump and use it to fill up one or two 2-liter Platypus bags for later drinking. While the Katadyn works extremely well and I’ve never experienced any problems resulting from the water I’ve pumped and later consumed, I’ve noticed that it is by far one of the heaviest pieces of gear that I carry when backpacking. My friend Andy has the Katadyn Hiker version which is more compact and equally as reliable, but still on the heavy side. I wanted a better, lighter solution.

Recently I’ve been taking along my home-made portable gravity water filtration system based on the one designed by Jason Klass. It uses an inexpensive Aquamira Frontier Pro water filter, Micropur water purification tablets, some tubing, and two Platypus 2-liter bags. Even combined it’s very light weight and has the advantage of being flexible enough to be used in different ways other than just for a gravity filter – for example I can use the clean bag and the tube as my hydration pack, or I can use the Aquamira and the bite valve to drink directly from a stream or water bottle of dirty water – the gravity filter is just an easy way to go UL and let the water’s own weight do the work for me while I go off and do other things. Below is a picture of the basic setup that I used during a backpacking trip this past weekend.

There are two Platypus bags used for this, one for dirty water (from the lake, creek, stream, wherever) and one for clean water. It’s very important that you clearly mark which bag (and cap) is for the dirty water so that you never use them the wrong way round. You should be able to see some large XXXs marked on the top (dirty) bag in the picture, the lid also has a large X on it. Once the dirty bag has been filled with water from the creek or stream, drop in two (one for every liter) Micropur water purification tablets and wait 20 – 30 mins. The Aquamira filter will filter out all of the nasty stuff down to 2 microns [edit: 3 microns], but just to be safe the Micropur tablets will kill all of the smaller stuff that’s lurking around in the water.

The Aquamira is designed to screw directly onto a standard bottle sized opening and fits snuggly onto the Platypus (dirty) bag. I remove the bite valve that comes as standard on the Aquamira filter and use the plastic tubing from my hydration pack (minus the bite valve is uses) to connect from the Aquamira to the second (clean) Platypus bag. The dirty bag has a little Kelty Triptease cord ties to it so that is can be hanged from a branch or notch. Now all that is left is to hand the dirty bag and wait for gravity to do the work. It took just under 14 minutes for all two liters of water to pass through the filter, which as it turned out was barely enough time to go throw the ball for Coco a few times :)

The result was two liters of crystal clear ice-cold refreshing water that had no taste of the purification tablets. There are many commercial gravity water filtration systems out there, including the Platypus one I blogged about recently, but most are expensive and use filters that cost almost as much as the whole device to replace. The system that Jason has devised and that I now use is cheap (~$40) and uses the Aquamira Frontier Pro as the workhorse which is good for 50 gallons of filtering and costs $20 to replace, other than the Micropur tablets, the other components should last a very long time if taken care of.

It’s very satisfying to come up with a better solution to an old problem. Even though this was dreamed up by Jason, I’m very pleased with how I’ve put mine together and how it has turned out to be a first class gravity filtration system. I hope you find this useful and be sure to check out Jason’s video.

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  • http://www.blogger.com/profile/05439540170889489974 Dave

    Over the years I have tired several water filters. Like most things that look cool, you never really know until you are out in the field and have to use it.

    The one one that I have found to be the most versatile is the Amigo Pro Gravity

    http://www.ula-equipment.com/amigo.htm

    not only is it very light weight but I can use it for scooping water from a very shallow stream of water, like from snow run off where there might only be an inch of water. The amigo Pro opens flat to scoop up the water and hang from a tree or rock.

  • http://www.blogger.com/profile/09628095804170935682 Brian

    The Amigo Pro is very cool, I hadn’t seen that before despite being a fan of ULA. I like how easy it is to fill, but don’t quite understand how it all goes together – there aren’t many good pictures on the site and the only YouTube video of it I could find was pretty poorly done. Still it looks like a much easier system to fill than a platypus bag :) I’m gonna stick with this for now and see what I can come up with to improve on it, maybe slice off the top of the dirty bag to make it easier to fill?

  • Alan in AZ

    I think it would be easiier for you to use a zip top platypus bag for the dirty water – should make filling much easier/faster (and cleaning much more effective back home)for a very small extra weight trade-off.

  • Anonymous

    Hi,

    There are alot of water filters in the market but they vary enormously. The key points to notice are

    1. The litres filters = cost per litre, so cheap is not best when you work this calculation

    2. The level of a micron it filters – so how small a bacteria it will filter 0.5 is the best on the market but some filters (most) only go to 2.0 of a micron so a big difference meaning more of a risk

    3. Now the big one Iodine tastes awful, takes time to be effective and most importantly has been BANNED in the European Union WHY?

    This eliminates nearly all Water Filters except ISTRAW & LIFESAVER. This ban is likely to roll out globally! I saw an article on GAPYEAR website that ISTRAW are just to launch a new bottle and straw using Ultrafiltration and will filter 99.99 of VIRUS and BACTERIA to 0.5 OF A MICRON and upto 1000 litres NOT using iodine. This will clearly make the new ISTRAWS the most effective and cost efficient water filters in the market!!! BEWARE do NOT use iodine based products they are bad for you ask the EUROPEAN UNION!

  • http://ewaterdirect.com/ water filtration company albuquerque

    Tap water is contaminated with chlorine and many other toxins. It’s also the most economical and convenient. I’ve checked out a lot of water filters and came to the conclusion that the Aquasana water filters are the most effective.

  • nuwati trekkers

    We are planning to build one of these filters and have been doing some research. I’m wondering why you use the tablets in addition to the filter?

  • http://www.blogger.com/profile/09628095804170935682 Brian

    nuwati, yes I always use Micropur tablets with this filter. I usually add the right amount of tablets (1) to the dirty bag and let it sit for the desired time. Then filter the whole thing because it actually removes a little of the taste from the tablets. But whether you use them before of after filtering is up to you, I just recommend using them for sure.

  • http://ewaterdirect.com/ water filtration company albuq

    Tap water is contaminated with chlorine and many other toxins. It’s also the most economical and convenient. I’ve checked out a lot of water filters and came to the conclusion that the Aquasana water filters are the most effective.

  • nuwati trekkers

    We are planning to build one of these filters and have been doing some research. I’m wondering why you use the tablets in addition to the filter?

  • Natalie Dalton

    Interesting post! I am new to this hiking stuff but have recently come to love it. I am always looking for new options for hiking water filters. I will have to try this out. Thanks for the great info!

  • http://www.facebook.com/people/Lawrence-Mak/100003257119990 Lawrence Mak

    No doubt we
    need a quality water purifier for drinking needs, some water purifiers has
    reverse osmosis membrane filter which has pore size as small as to 0.0001
    micron, so it can filter out the most contaminants, i recommend Coway water
    purifier.

    http://www.cowaywaterpurifier.com/

  • http://berkeywaterfilterinfo.com/ Ben

    wow, this is really Diy style. Good job.