The mineral buildup on this unit is horrible. After the first week of use, it took 3 repeats of the cleaning process and then I still had to soak a paper towel in vinegar and leave it on the heating element several times with scrubbing with a toothbrush in between. After the second week of this, I tried distilled water for 2 days and still had a mineral buildup issue. I then tried filtered water and 2 days later, same thing. I called Honeywell customer service and they did not have a better way to clean the unit. I thought I would save money by not getting a humidifier with a filter but that is not the case. I am spending way too much time cleaning this unit, not to mention all the white vinegar. I'm sure my area must have hard water but I can't imagine why distilled water didn't have a better outcome. Customer Service said since it was still working, there was nothing they could do.