The safety and quality of your water supply may be the key consideration in deciding whether to use distilled water in the humidifier. Boiling water will kill microbes, but it will not remove minerals or chemical contaminants. These minerals that make water “hard” include calcium, magnesium, iron, and others. If they are present in the water put in the humidifier’s water chamber, over time scale will develop that discolors the container and could damage the device. Filtered water may remove some of the minerals but may not remove living organisms or other chemicals. Bottled water that has been distilled may be an alternative option to regular tap water. The use of distilled water will maximize the life of the water tub by reducing the buildup of mineral deposits. Distilled water is available to buy at many grocery stores