This ozone appliance for the professional dental office and other medical applications introduces dissolved ozone into dental and surgical operatory water lines. This dissolved ozone can not only disinfect water and water lines; it can also reduce gum bleeding, gingivitis, bad breath, teeth stains and oral bacteria. Additionally, it can aid in wound disinfection in surgery and attack microbial contamination of water from dental and surgical operatory water lines and attached hand pieces and dispensing devices by automatically killing waterborne germs and destroying biofilms where germs can hide and grow. It can, therefore, be used to disinfect water lines in dental operations and for other medical applications such as providing liquid containing ozone for cleaning and disinfecting skin prior to surgery (and tissue exposed during surgery). Further, a unit connected to operatory water lines can give an audible or other alarm if the water becomes unsafe.