they mentioned it is always recommended to fill in the water tank, if not it will affect the life span of the machine.
Since i sleep with open windows and fans only, i normally dont use the humidifier . Not sure how true is their advice.
It is possible to operate the Resmed 10 without water in the tub. You can also disable humidification in the settings. You can also purchase and use the optional side cover to replace the water chamber.
ResMed: What happens if the water tub runs out of water?