The Water Filter used by missionaries in the Third World Countries for over 140 years!
It's gravity fed. No electricity is needed. Its ceramic filters safely remove dangerous waterborne pathogens such as cysts (Cryptospordium, Giardia, Lambilia), bacteria (E. Coli, Salmonella, Typhus...), viruses (Polio, Rota Virus, and Ebola). Nothing escapes except pure water.