- Steam Irons and Softened Water Water Quality Answers Can softened water be used for a steam iron Neither hard nor soft water should be used with a steam iron. Distilled water, or water treated by reverse osmosis, is acceptable for use over a period of time. Bear in mind that the softening of water does not remove the minerals, but that they can be more easily rinsed from the iron with softened ...www.wqa.org/sitelogic.cfm?ID=365