Water filters

According to research by Micha Hummler:

Original Plans from Josh Kearns and Aqueous Solutions: *http://www.aqsolutions.org/

Here is a $90 DIY water filter for purifying rainwater to drinking quality. Bill of materials and instructions are included (CC-SA license):

http://www.aqsolutions.org/images/2008/05/bucket-filter.pdf