Why do I have to use distilled water?
Distilled water should be used when a humidifier containing acrylic polymer is in use. The acrylic polymer releases moisture through fine pores. If ordinary water is used, these pores can become blocked over time, reducing the humidifier’s performance.
https://zigarrenversand.ch/en/Cigars-FAQ/Storing-cigars-at-home/Why-do-I-have-to-use-distilled-water