On a recent late summer overnight at Mount Saint Helens, I set camp up at/above tree-line and was able to find water from the melting glacier/ice field near the rim. The challenge is that because there had been no significant precipitation in over six weeks, when the water reach our access point, it was so filled with ash sediment that I knew was going to clog my filter on the first pass. I pre-filtered the water through a bandana (twice), but the filter still became clogged. We used some of our clean water to backflush, but that was not enough.
Once I came back to civilization, I began researching this problem and discovered millbank bags. They seem very effective to use as a pre-filter before filtering through a Sawyer/Katadyn/etc. (with purification afterwards, if necessary). My question is this: Do you have any experience using a millbank bag and if so, do you believe that it would be effective at filtering out most of the ash/sediment from a volcano water source?
