Quote Originally Posted by cls515
Basket, the distilled water will still have minerals in it, just not in as high a concentration as the tap water. This is pulled from the same article:
Use distilled water: The health impact of humidifiers depends a lot on the quality of water used in it. About 90% of compounds dissolved in water (including lead, aluminum, and asbestos) may be spewed by ultrasonic humidifiers as small particles that may result in chronic (long-term) respiratory problems. To prevent that, use distilled water in your humidifier to reduce the mineral content in the mist because distillation is the best way of removing minerals from water. Do not use tap water because it has a high mineral content—especially if you have well water. Even though distilled water may still contain some mineral content, it will probably have fewer minerals than tap water.
Ahh I see. So I guess after a long time there is some residue left over. I use beads so I haven't seen the long term affect on using one of those other humidifiers.