anyone using a gravity filter

[Michael Davis]

Aaron, I use a Sawyer viral filter, which has very similar specs compared to First Needs, in a gravity configuration. I haven't timed it but I know it doesn't take anywhere near 13.5 minutes per liter.

However, the trick with this one at least, is to prime the filter before your trip by backflushing is with the faucet attachment and leave the water in it!

This system doesn't save weight; the gravity bag + hose + dry filter weighs 9.6oz but with the wet filter, it all adds up to 14.9 oz.

However, it does save work and it filters everything, including viruses from swamp water, without any waiting or chemical side effects.

I use a Steripen Adventurer in clear mountain streams and with either system, I carry chlorine dioxide tablets as back-up.

[Keith Selbo]

The Sawyer viral filter won't get rid of chemicals by itself so if that's an issue, you need to add a charcoal filter.

BUT, if you include a charcoal filter, you can also add a little chlorine (2 drops/liter) to the water to kill viruses. The charcoal will remove the chlorine after it does its job and many other chemicals as well. Then you can use the considerably cheaper Sawyer 0.1 micron filter which removes everything except viruses.

I never timed it, but if I had to guess, the flow must be a half liter per minute.

There's a photo of this combination in this thread:
http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=18595&skip_to_post=144804#144804

[Aaron Lastname]

Thanks Michael, I have been looking at that filter, but was scared away by the REI listed weight of 20oz, no better than my First Need. However it appears that 20oz must be incorrect or the system can be broken down into something lighter. Your system would still save me a lot of weight – My First Need with cartridge and pump weighs 22oz with a used canister. I find the listed weight of 16oz incorrect, and it seems that after you use the cartridge one time, it gains 4oz. (I have a cartridge I've used that was flushed out after use and has been sitting in my closet for 6 months, and it is still 4oz heavier than a new one) I guess with that Sawyer I would be losing that ability to turn blue water clear and remove bad taste while reducing any heavy metals and chemicals, but gaining in that I would never have to replace a cartridge. Hmmmm.

[Aaron Lastname]

Herman, I like that setup. Kinda going against my "Mantra" to add chlorine and then take try to take it out, but hey that's the same thing I do at home (Or try to) with my Brita. Maybe I'll have to make some compromises to achieve my goal!

[Aaron Lastname]

Now that I think about it maybe Michael's viral filter with the Katadyn charcoal filter is the way to go. Don't know about flow rate, though. No chems added, however.

[Justin Marney]

@Michael & @Herman Is this the Sawyer you guys are using? http://www.sawyerproducts.com/SP121.htm Is it possible to prime the filter on the trail or does it take more pressure than one could muster via lung power?

[mike leary]

How about a Berke Filter. A smaller one like the big berkey or berkey light would be good as a base camp solution. albeit a little bulky to manage.

http://www.bigberkeywaterfilters.com/berkey-filter-systems-c-1/big-berkey-p-182

[Walter Carrington]

A possible easy way to set up a water filter is to use the top for a nalgene water bottle with nipple:
http://www.campmor.com/outdoor/gear/Product___23234
If you pull the moveable part of this nipple you have a nipple about 10mm in diameter. If this fits the tubing required for the filter, then use this wide mouth 96 oz polyethelene water bottle:
http://www.rei.com/product/626195
The question is the diameter the same as the filters. I'm thinking of using a 0.1 sawyer filter

[Samson lee]

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[Ken Larson]

http://www.backpackinglight.com/cgi-bin/backpackinglight/reviews/display_reviews.html?forum_thread_id=5536&skip_to_post=251982#251982

[Gary Ward]

I'm surprised there is not more current postings on this topic. It seems there have been some improvements in the last few years on the gravity feed filtration systems. I have an MSR that works great.

I've used the pump-MSR as well. I have one that has lasted about 15 years and still works great with its ceramic filter. It is the old standby. I tried the UV bio-killer pens, but kept having issues with them. I was not impressed. These need some further development to make them bombproof.

I had absolutely no issues this past summer with the MSR gravity feed system. My partner used the Katadyne gravity feed system with the filter in the bag and has some trouble with it being very slow. It was not as easy to flush as the MSR system and she was almost ready to give up until I told her about the MSR system. But to be fair, she was using the Katadyne system in an area with a fair amount of glacial silt washing through, whereas I wasn't.

http://vodpod.com/watch/1914324-backpacking-the-west-coast-trail

[Author]

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