- Instructions for making a water filter from gravel, sand, grass and a plastic bottle: appropedia: UV_Water_Purification
- UV LEDs can be used to kill pathogens and are cheap. The 'Pure Bottle' uses a hand-powered UV bulb: ]. Steripen is similar: . An open-source version of these would be nice.
- Slow sand filter with layers of fine sand at the top, coarse sand in the middle and gravel at the bottom.
- 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
- Ceramic Water Filter: http://other90.cooperhewitt.org/Design/ceramic-water-filter
- Potters For Peace - Water filters
- Potters For Peace on colloidal silver for water filters
- charcoal filter: inexpensive and very effective. Best if produced in an "open burn" type of kiln that is good at mobilizing the volatiles (e.g. Kon-Tiki Kiln). Quenching with water/steam can remove additional volatiles.