So who's got a gravity water filter, which one do you have, and how do you like it?
I've been using the MSR AutoFlow for awhile now and have been quite impressed. The fact that it weighs in around 10 oz, filters at about 2L per minute, can be effectively cleaned by reversing the flow, and is the easiest filtering solution I've ever used making it my go-to backcountry filtering solution. I've used it numerous times on the Colorado River and have not had any problems with clogging.
Having said that, it isn't the best solution for humic acid (ie., Boundary Waters) or blue-green algae prone areas (ie., High Uintahs). If these exist in the areas you frequent then a hollow fiber based filter might not be the best choice. I would go with a filter that uses a ceramic cartridge (I don't think there is a ceramic gravity filter available but I could be wrong).
The best part about the filter is that I have instant water without work. It's awesome! Check it out here.
Believe, then you will Understand...
I think this would be simple to do. The key is allowing the bag to hang while still allowing the water to gravity feed through the filter, and catching the clean water in a container. This is different from other gravity feed filters in that most have the filter element in the bag.
Another solution would be the Platypus CleanStream which uses the same filter element as the AutoFlow, but uses Playtpus bags to carry the water (dirty water bag and clean water bag). You could save weight by not carrying the clean water bag and catching the clean water in another bag/bottle. This would probably save about 5 ounces or so.
One added benefit to this filter is the filter element can be used as an inline filter in a hydration system. Because the flow rate is so good, there is almost no reduction in flow rate as the users sucks water from his reservoir. This is great to have for mountain biking in an emergency...
Believe, then you will Understand...
In another post months ago, there was a discussion about gravity filters. Jason Klass posted his DIY filter using a Katadine filter and a bag of his design. I was inspired by the fact of not having to pump water. I went looking around for that filter and couldn't find it for my impulse purchase. I ended up buying the Katadine Base camp. But found the bag bullit proof and on the heavy side. My plan now is to retro fit the filter into a Jason Klass type bag.
I'm confused. Jason's video has him using chemicals with the filter but the Aqua Mira web site does not say anything about needing to use anything in addition to the filter. Do you need to use Aqua Mira with the filter or not? How many gallons can you run through this filter before you need to replace it?
If I wouldn't eat it at home, why would I want to eat it on the trail?
I have used ULA's gravity filter the Amigo Pro and very much liked it - I misplaced mine but will get another when I'm backpacking again in spring. The cost is about five dollars more than what one would pay for a replacement Katadyn HIker Pro cartridge. That filter impressed many in my hiking group. One of them picked up the Katadyn gravity filter, but that weighs a lot more than the eight ounces of the Amigo.
I also have a Hiker Pro that comes in handy late in the year when water sources can be very shallow and not suited to scooping water.
Using chemicals in addition to filtering is what the MSR Sweetwater system does, as this addresses viruses too. I am usually in the Sierras where the issue is mainly bacteria and cysts, which the filters all handle. I do carry Micropur tablets in my emergency kit so if a water source I am forced to use is suspect, I would likely use the tablets in addition to the filter.
"In the beginner's mind there are many possibilities. In the expert's mind there are few." Shunryu Suzuki
I have the Platy and love the silly thing. Talk about the quick and lazy way to get clean water; Fill it, hang it and relax. With a bit of trimming of the hoses, and by not using the clean bag I got the weight down to 8.2 oz.( I will probably even modify it some more). The hose from the filter also has a male fitting that screws on to Platy drinking bladders and most convenience store water bottles, leaving you free to do other things while filtering.
Loc: Gateway to Columbia Gorge
I also have the ULA Amigo Pro and love it! No pumping (which was putting my back into spasms bent over the water source) and definitely lighter than most pump filters.
The one improvement I'd like to see on it is a shaped water "bucket" of silnylon instead of the round piece of silnylon with drawstrings. The former would be much easier for dipping the water out of the stream. It would also be easier for those locations (such as most lakeshores) where you have to fill the "bucket" by dipping water out with a pot and pouring it in. Of course, making the shaped "bucket" would cost more.
Edited by OregonMouse (12/05/0805:31 PM)
May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view--E. Abbey
Loc: Menlo Park, CA/Sierra Nevada
This past summer I made a gravity filter from some silnylon, a katadyn Pur hiker filter, and some tubing (using some instructions I found online that I can't seem to find now). After a few years of using aquamira I'm not sure if I will go back. That darn thing was awsome...I think my one complaint was having to hold the filter when there wasn't anything else willing (eg above treeline or with my wife)
I assume that was not a free sample, since it's a fairly big piece of Cuben. Where did you get it, and how much was it?
Also, can you describe how you made the bag (what's it edged with at the top, did you reinforce the "drain" at the bottom, etc.)?
We just got an Amigo and haven't used it yet, but I'm looking at trying to lighten it up some. Your setup looks great!
For those who were wishing for a more structured bag for shallower water, I did read somewhere that some people use a water "scoop" to fill the bag, I think made out of a soda bottle with one end cut off. It could be used to store the filter setup, making it somewhat multi-purpose.
(edit) I just looked it up and actually the scoop recommended was an old 1L platypus bag with the end cut off at a slant.
I got the Cuben sample from the manufacture a wile back and it was free. They had sent me a single yard of a few types. However I read the company has sold to another textile manufacture so I'm not sure. You can however find it online from a few of fabric venders like OWF.
The red edging is made by bending a piece of 1" red gross grain then sewing. The holes are 1/4" and made with a tool that is hit with a hammer. You can find the tool and kit in most sewing shops. I happen to have a friend who has a press that will do a few size but for this 1/4" is fine and the kits don't cost much.
Does anyone have a good suggestion for a filter that can help take some of the tannic coloring out of the water? Down here in Florida a lot of the streams and rivers are pretty dark looking. Sometimes you can taste and sometimes you can't but I would really like to find a way to filter out the color.
I've used my PUR Hiker before, but it really doesn't filter out the color of the water.
Some people are like Slinkies.You can't help smiling when they tumble down the stairs
“Does anyone have a good suggestion for a filter that can help take some of the tannic coloring out of the water?”
I only know of one filter and if someone knows of another filter, I would like to know. I’ve tried ceramics and other supposed carbon filters. The First Need is the only one I’ve seen that filters out the gross color that I have been privileged to drink from around here.
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