Very quiet. I love that this has a dial to adjust the output, and the optional light settings. We use only filtered or distilled water, and it has stayed very clean. It has already been a great help for the dry winter air in our home.
Nice humidifier. We live in a Cottage w/a pellet stove for heat that dries our woodwork out. This is keeping the livingroom area at about 40% humidity. Very good. I do go through One gallon of Distilled water daily.
This humidifier is GREAT! I had previously bought another brand, but was not happy with it at all. It claimed to last up to 12 hours when really it only lasted about 4. This lasts all night! I can use this for a few nights in a row before having to refill! Love it.