I keep trying to find solutions for SHTF that don't rely on electricity, modern technology, or spare parts that can't be made at home, or would dissapear quickly in SHTF...I had only one problem...couldn't find a water purification system that wouldn't rely on expensive filters. I ran into Bio Sand filter. Biosandfilter.org I red everything I could find about it, all projects, testemonies and analysis...even from MIT...I also have some ideas about adding another filter layer of active carbon... If this thing works in Africa and Asia, it must work here too, and our waters are much cleaner... Any remarks, suggestions or comments are welcome. Cheers!