Platypus Water Filter - Gravity Works 2l Complete Kit
Last summer we found ourselves in California visiting friends. During the trip we spent some time in the Sierra Nevada mountains, a stunningly beautiful area crammed full of rivers and lakes. Swimming in them is not a problem, but drinking from them can be thanks to a couple of pesky bugs; e-coli and giardia. Picking up either can be pretty nasty and long term. We knew this and had with us an ultra violet purifier. Unfortunately, right when we needed it, on the first morning of a three day walk from Tuolumne Meadows to Yosemite Valley, it packed in. Faced with the prospect of having to boil all our water a fellow walker offered to lend us his gravity filter on the understanding that we would find him later and return it. It was amazing. Having spent decades using tablets, iodine and more lately, ultra violet to purify water, this relatively new technology was an eye opener. On returning home we equipped ourselves with a suitable gravity filter.
The Platypus Complete Kit is aimed at groups of around 4 people and comprises a bag for dirty water, a connecting hose with a clamp (essentially a tap), and the all-important filter. In addition there is a second, longer hose for connecting the filter to a clean bottle (also provide), and a number of adapters and fittings to fit most bottles. There are a few important rules - don’t drop the filter (it's fragile), always connect the filter using the direction arrow printed on its side, never mix up the two hoses or bottles (one of each are for dirty water, the other is for clean, and give the filter a back-wash from time to time.
Setting it up could hardly be easier. The dirty bag unrolls and has a wide opening meaning that it can be filled quickly from either standing or moving water. Close the top, hang the bag up somewhere a few feet off the ground using the attached strap, and connect the short dirty hose to the correct end of the filter. You can either let the clean water fall straight into your receptacle as it would from a kitchen tap, or you can fit the other hose and fill your bottle/s without any exposure to the air. There's a small black plastic clip which can be fitted to either hose, but I opted for the dirty water hose as it you opt to not use the clean hose you still have the option of controlling the flow rate. Simply squeeze the clamp together and it closes the flow. It's really that simple. Open the clamp / tap and the dirty water will pass through the filter at a rate of 1.5l per minute. 10 minutes effort at the start of the day can see your whole family's bottles filled for the day, or you can get it out during the day and fill as you go if you know you are going to be passing water.
In terms of what it can filter, the obvious no-no is sea water. It'd be nice to think that one day we'll be able to carry a similar gadget that will work on brine - imagine the possibilities - but alas it's not here yet. There's also a warning not to filter chemically treated water, water or from mine workings. There's a lower particle size limit of 2 microns. I've no idea how small that is in real terms, but it also recommends against filtering muddy water where possible, presumably to prolong the life of the filter. It's recommended to backwash the filter ever 2-4 litres to clean it.
The whole kit weighs 326g, but if you are going light weight then you can easily manage with just the dirty bag, dirty hose, clamp and filter which reduces the weight to 198g. That's impressively light when backpacking.
Other nice features include a small carry bag, with two zipped sections, one for dirty and one for clean, and the fact that you can connect up the hose to your water bladder in your rucksack to the clean water hose and fill your bladder without having to remove it.
It retails at $109.95, and is available for around £75 online from British website. Weigh up that cost against contracting giardia and it's an absolute bargain.