When I’m off hunting and fishing at the camp, I usually bring clean water. But I like to have backup option. The thing is that « real » and safe filters are way too expensive to use merely as backups. That’s why I like to use chlorine dioxide (by Pristine), that give a better taste than Iodine. Also, the steripen (the Classic model) offers quick, easy and very safe way to treat water. But I was a little disapointed with its prefilter, that is 40 microns wide.
Here’s a quick way to transform an emergency straw type filter into a gravity flow drip system that can filter nasties down to 3 microns. Exit the tubing, valve, collapsible water container, glue, CamelBak, and ... technology.
Keep it simple and light!
Step 1: What you need
A Pristine Pioneer Emergency filter or Aquamira Frontier Filter. May not be the safest filters out there, but remember; I use this setup as a prefilter and a backup, before treating the water with UV or chemicals. You can buy one for about 15$. It can filter about 75 liters (enough for a fishing season!)
Step 2: The Funnel
Step 3: The Filter
Ditch the straw. Insert the filter tightly in the bottleneck, making sure the output end of the filter is on the outside of the bottle. With the bottle I used, the seal was quite tight. I guess one could use a length of tape to make it really watertight.