From the research I’ve done I would say Colloidal silver can be used to purify water. The ISS, Mir and WHO all list Colloidal silver as a disinfectant. Put this link in for you from Natural News:

http://www.naturalnews.com/034904_colloidal_silver_MRSA_candida.html

Good reliable site and I love that they put all the links they site at the bottom of their articles. I guess it’s just about working out the level of silver to amount of water and that would have to factor in the concentration of the silver I think. Still, nice to know there is an alternative source for sustainable disinfectant. Also liked your article. Good prepping info is always helpful to everyone.