Will purified water hurt your cpap machine?

Answer 1

That depends on how the water was purified. The thing you want to avoid is dissolved minerals, which can build up in the humidifier of the CPAP. Distilled water is recommended because dissolved minerals cannot cross the distillation process. Other forms of "purification" such as filtering or semi-permeable membranes can leave minerals dissolved in the water.

With that said, I bought distilled water from a drugstore in Japan that was also labeled (in English) "Purified water". I have also used tap water on rare occasions when distilled water was not feasible. After doing so, I clean out the humidifer with vinegar (which dissolves the mineral residue - be sure to rinse well!).