Method for sanitizing water supply system

A method for controlling ozonation in a water supply system comprising an ozonator, a controller functionally connected to the ozonator, a flow meter configured for detecting a flowrate through the water supply system, a valve configured for turning on or off of the water supply system, said method comprising using the controller for:

• (a) determining a time period in which the water supply system has continuously not been requested and a time period in which the ozonation has continuously not been performed, wherein a water supply system request is determined based on the flowrate through the water supply system;
• and
• (b) if said time period in which the water supply system has continuously not been requested exceeds a lack of water use threshold and said time period in which ozonation has continuously not been performed exceeds a lack of ozonation threshold, executing a counteraction pair including a first action at a start time and a second action at an end time, wherein said first action comprises turning on the water supply system and turning on the ozonator and said lack of water use threshold is at least about 1-2 hours and said lack of ozonation threshold is at least about 1-2 hours.