http://forums.equipped.org/ubbthreads.php?ubb=showflat&Main=17477&Number=246425#Post246425The above links to an earlier thread giving instructions on how to disinfectant water with pool shock.
There were additional posts which I can't find right now. If I can pull them up I'll update this post.
Test strips for water purification:
http://forums.equipped.org/ubbthreads.php?ubb=showflat&Number=276756Some CDC info:
http://www.cdc.gov/safewater/chlorination-faq.html