My husband uses distilled water for his BPAP machine. There have been issues with availability/supply chain the last couple years. It was getting frustrating until I learned these machines existed for using in the home setting. The reviews looked good and cost was reasonable so I purchased one. My husband wasn't excited like I was at first, but found it to be easy, convenient, and useful after about a month of use. He finally thanked me for the thoughtful purchase.