If a filter was used with RainCloud, it would have to be flexible to be press fitted into the 2 liter bottle. Thank you for the site recommendations, I will check them out.
I orginally planned to have RainCloud to be field tested over the summer in Bangalore, however, the partnership fell through. I am currently working with Power2Become to have it tested and implemented in Burkina Faso this December.
Collection of rain water is a great idea for clean water source! I know if water is left in the sun (UV rays) long enough bacteria is killed, however I am not sure what effect (if any) it has on chemical neutralization.