There have been several studies on the efficacy of various water treatment chemicals including iodine and household bleach. Most chemicals work well on bacteria and viruses but few are truly effective against encysted Protozoa such as giardia and cryptosporidium. Iodine and bleach are not among those that are reliably effective against cysts. Chlorine dioxide compounds such as Micropur are effective against cysts but only given about four hours contact. Cysts are best removed by filtration. For really cruddy water I will filter first and then add ClO2 as Aquamira or Micropur.
Iodine has been shown to cause a number of health issues if used in excessive amounts and what is excessive is highly variable. When I was in the Army I drank a lot of iodine-treated water. I was OK for short periods but after a month or so I would suffer a low grade general malaise that I attributed to iodine. Now, I will use it only if there is no alternative.
Edited by Pika (08/12/13 08:56 AM)
May I walk in beauty.