Method for sanitizing water supply system

A method for controlling ozonation in a water supply system comprising an ozonator, the water supply system 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 water supply system for:

• (a) determining at least one event from flowrate data of the flow meter over a time period of a plurality of days, said event comprising a time span within a day in which the flowrate remains below or at a threshold value over said time span within a day for each day of said plurality of days;
• (b) determining overlaps of said each event to another one of said each event of all days within said time period;
• and (c) determining a frequency of the overlaps of said each event over said time period;
• and (d) determining a requirement for ozone, wherein if the frequency exceeds a frequency threshold and said requirement for ozone exists, a counteraction pair including a first action and a second action in opposition to the first action is executed during a time span corresponding to said each event, wherein said first action is executed at a start time within said time span corresponding to said each event and said second action is executed at an end time within said time span, wherein said first action comprises turning on the water supply system and turning on the ozonator.