A plumbing fixture sanitising system comprising: a cistern for storing water; a supply pipe arranged to supply water to the cistern; a first plumbing fixture comprising a water inlet arranged to receive water from the cistern; and an electrochemical cell assembly arranged in the supply pipe, the electrochemical cell assembly operable to produce ozone from the electrolysis of water, wherein the electrochemical cell assembly is arranged to produce ozone at a concentration of at least 0.7 ppm; a control system comprising: an inlet valve arranged on the supply pipe, moveable between: an open position where water can flow through the supply pipe; and an inhibited position where water is inhibited from flowing through the supply pipe; a cistern valve for selectively inhibiting flow of water from the cistern to the first plumbing fixture; and a controller configured to: control operation of the inlet valve between the open and inhibited positions; actuate the inlet valve at a first time to allow a flow of water through the supply pipe to the cistern with the cistern valve in a closed position; control operation of the electrochemical cell assembly to produce ozone when the inlet valve is in the open position, and cease production of ozone when the inlet valve is in the inhibited position; and open the cistern valve a predetermined delay period after the first time, the predetermined delay period for filling the cistern to produce a head pressure for mechanical cleaning of the first plumbing fixture. a cistern for storing water; a supply pipe arranged to supply water to the cistern; a first plumbing fixture comprising a water inlet arranged to receive water from the cistern; and an electrochemical cell assembly arranged in the supply pipe, the electrochemical cell assembly operable to produce ozone from the electrolysis of water, wherein the electrochemical cell assembly is arranged to produce ozone at a concentration of at least 0.7 ppm; a control system comprising: an inlet valve arranged on the supply pipe, moveable between: an open position where water can flow through the supply pipe; and an inhibited position where water is inhibited from flowing through the supply pipe; a cistern valve for selectively inhibiting flow of water from the cistern to the first plumbing fixture; and a controller configured to: control operation of the inlet valve between the open and inhibited positions; actuate the inlet valve at a first time to allow a flow of water through the supply pipe to the cistern with the cistern valve in a closed position; control operation of the electrochemical cell assembly to produce ozone when the inlet valve is in the open position, and cease production of ozone when the inlet valve is in the inhibited position; and open the cistern valve a predetermined delay period after the first time, the predetermined delay period for filling the cistern to produce a head pressure for mechanical cleaning of the first plumbing fixture. an inlet valve arranged on the supply pipe, moveable between: an open position where water can flow through the supply pipe; and an inhibited position where water is inhibited from flowing through the supply pipe; an open position where water can flow through the supply pipe; and an inhibited position where water is inhibited from flowing through the supply pipe; a cistern valve for selectively inhibiting flow of water from the cistern to the first plumbing fixture; and a controller configured to: control operation of the inlet valve between the open and inhibited positions; actuate the inlet valve at a first time to allow a flow of water through the supply pipe to the cistern with the cistern valve in a closed position; control operation of the electrochemical cell assembly to produce ozone when the inlet valve is in the open position, and cease production of ozone when the inlet valve is in the inhibited position; and open the cistern valve a predetermined delay period after the first time, the predetermined delay period for filling the cistern to produce a head pressure for mechanical cleaning of the first plumbing fixture. control operation of the inlet valve between the open and inhibited positions; actuate the inlet valve at a first time to allow a flow of water through the supply pipe to the cistern with the cistern valve in a closed position; control operation of the electrochemical cell assembly to produce ozone when the inlet valve is in the open position, and cease production of ozone when the inlet valve is in the inhibited position; and open the cistern valve a predetermined delay period after the first time, the predetermined delay period for filling the cistern to produce a head pressure for mechanical cleaning of the first plumbing fixture.