Iodine in Water
Elemental iodine and iodides occur only as traces in natural fresh waters. In contrast with chlorine, elemental iodine is only slightly soluble in water except in the presence of iodides.
It is not appreciably hydrolyzed in weak acid solution. It has been reported that 8 mg/L of iodine destroy all forms of water borne pathogens, but no adverse affects were noted when personnel in the tropics used drinking water containing sodium iodide at a concentration of 12 mg of iodine per man per day. Very little information exists on the effects of iodine on fish and aquatic life.