View Full Version : Water Filtration: Gravity or Pump?
OTdarters
09-23-2008, 19:39
Hi Everybody!
I'm looking for opinions about water filters. I've read various things about both pump and gravity filters, but I don't know which would be best.
Quite simply, which do you prefer?
I've read that pump filters are prone to breakage, and my experience concurs, but pumping is still fast.
Gravity filters (if you're not familiar, water bags with a filter on the bottom, gravity pulls the water through the filter while you wait) seem interesting from what I've read. Supposedly, no moving parts, light weight, impossible to break. But I'm still wondering whether having to wait for filtered water would be an obstacle while on the trail. Is it practical to filter all the water for a day while in camp, or would it be necessary to wait excessively?
Thanks for your help!
Alligator
09-23-2008, 20:30
I have a Sawyer that I use as an inline and a gravity filter. I timed it at under sixty seconds for a liter, I think it was low fifties offhand. So for that model not a problem.
firemountain
09-23-2008, 20:55
I've used the Katahdin Hiker Pro and the Aquamira Frontier Pro, now I happily use aquamira drops. The hiker pro was great except for two broken handle, cracked input port, and clogging the filter. I was able to fix all these issues in the field and the filter never let me down. The frontier pro inline filter is very small and light, I bought it as a transition item to help me feel more comfortable using aquamira drops. It is great for when water is very scarce and murky or the source has many particles. The small prefilter quickly clogs but is very easy to clean or replace. The flow rate is very slow however. The filter comes with a type of bite valve, but I cut this away in an attempt to improve the flow. This helped somewhat but it still takes a few minutes to get your water.
Now I use aquamira drops which only weigh 85g and taste delicious!
Are you willing to wait (for the gravity filter?) One of the advantages of pump-filter units (over chemical treatments) is having drinkable water as soon as you find a water source.
take-a-knee
09-23-2008, 22:12
I just built one of these, mine weighed 5.7 ounces, not including the nalgene I cut up, it cost $50.
http://www.tothewoods.net/HomemadeGearGravityFilter.html
BookBurner
09-23-2008, 23:05
I don't want to disregard your original question, but are Aquamira drops an option you are aware of? They definately get my vote. Light, compact, fast, and neutral (if not pleasant) tasting.
Pump. First Need 1lb. - heavy. I've used the same pump unit since 1998. I've gone through several filters - up to 200 gal each, but haven't had any mechanical problems. The cartridge is sealed and must be replaced when it clogs, but it eliminates viruses as well as protozoan pests such as g. lamblia and crypto.
I just started using a Sawyer Inline filter (Walmart, $39 +tax) between two Platys and just filtered 70oz of water in 5 mins 13 sec. My rig also includes an inline carbon filter for sources with lots of organics (skunky water) so that slows the flow rate.
It now takes first position ahead of my Steripen and MSR Miniworks given it's minimal effort and fast fill times. I wouldn't go back to a pump unless I start having serious problems with this down the road and couldn't find a suitable gravity-based alternative. I still keep MP tabs as a backup and iodine in my IFAK.
As a substitute for the loss of pumping action I use a modified 1 ltr platy as a folding cup to get water out of shallow areas and have seen others use bulb-type fuel hand pumps used on boats (also at Walmart, two isles over).
I just started using a Sawyer Inline filter (Walmart, $39 +tax) between two Platys and just filtered 70oz of water in 5 mins 13 sec. My rig also includes an inline carbon filter for sources with lots of organics (skunky water) so that slows the flow rate.
That is amazingly fast. Faster than any pump-filter I've used. :-?
Alligator
09-24-2008, 08:20
That is amazingly fast. Faster than any pump-filter I've used. :-?I timed a liter at 52 seconds with mine. It was kitchen water mind you but when I used it in the field it appeared just as fast. I didn't time it there. I do simply raise my hydration bladder over my head and let it filter into a one liter platypus. I haven't run anything particularly muddy through it so I can't speak to that or long term clogging issues. The filter is guaranteed for life though in regard to clogging, but again, I haven't needed to test the guarantee.
That is amazingly fast. Faster than any pump-filter I've used. :-?
I should have added a caveat that the filter is almost brand new. So far I've only put through ~20 liters of lake water. I haven't tried it on water with fine silt. Supposedly you can backflush it and it works like new but then again everybody thought the Hyperflow was going to be the end all be all and it turned out to have issues.
We'll see how it does around 200 liters with something more murky.
SunnyWalker
09-26-2008, 17:23
I have been satisfied with a pump. The brand I use is Sweetwater. Have used this is Rockies, Sangre de Cristo Mtns., and AT.