How long is it safe to use iodine water treatments?

1-2 weeks. If there is a chance of micro-organisms in drinking water, it needs to be treated. Iodine can be safely used to kill most micro-organisms for up to a few weeks, but should not be used by people with thyroid conditions or pregnant women, and kept out of reach by children. For longer trips, other treatments should be used. Read more here: http://wwwnc.Cdc.Gov/travel/page/water-treatment.Htm.