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Using a Gravity Water Filtration System

Clean up water for a group in minutes by using a gravity filter. Here's how one works:
Photos by Kim Phillips
  • Dunk the "dirty" hydration vessel into your water source.
  • Use a cup or bowl to fill the bag to maximum capacity.
  • Attach the filtration unit and hose to your dirty bag if it's not already attached.
  • Then secure the other end of the filtration unit to the "clean" bag.
  • Most filters, like the one pictured, have a "clean" side and a "dirty" side that should be attached to corresponding bags.
  • Attach the filter to your "clean" bag.
  • Find a tree or bush to hang the dirty bag and allow "gravity" to work its magic by forcing the water down and through the filter into the "clean" bag.
  • After the filtration is complete and the "clean" bag is full, you can transfer the drinking water to a number of other hydration units.
Dunk the "dirty" hydration vessel into your water source.
Image 1 of 8

Dunk the "dirty" hydration vessel into your water source.


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I have used this type of gravity filtration system for years. It's the best. The small hand pump type is fine, but you seem to spend half your day pumping water. I need water for drinking, cooking, dish washing and bathing so the 4L size is great.
— tafratzke

You should really mention basic steps likes "Lift the clean bag above the dirty one for 10-20 seconds when you're done to backflush the filter" This is a basic step that every manufacturer recommends.
— Ian

This system does not clear water of viral infection. Only chem treatment does that. It's a mistake to tell people that filtering water only is going to give them clean, safe water. Not true.
— Earle

It is actually possible to buy a gravity purification system from sawyer, which treats for viral also. Treatment systems do not treat for viral, and purification systems do.
— Reed

I tried one of these during a drought year in Vermont. All the water sources were cloudy/silty and the filter quickly clogged up, with no way to easily clean it. As a result, I had to sit on the hydration bladder to pressure the water through the filter. I switch to a pump which is easy to protect with pre-filters and easy to clean.
— Richard

When you fill the raw water bag, you shouldn't use your drinking cup or any pot that you don't intend to sanitize before using. Only clean water in your cup and water bottle.
— Bill

I don't filter water for bathing or cooking. Seems excessive. I spend all my time in the Rockies and west of there to the coast so the water is generally very good.
Has anyone used one of these a lot in the SW canyons or in streams loaded with glacial silt? I'd like to hear of your experiences.
— Mike


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