Patent ID: 8650935

Claim:
A method of determining the total organic carbon (TOC) of a purified water stream, comprising at least the steps of: (a) passing a supply water stream through a water purification apparatus including an oxidiser and one or more ion-exchangers downstream of the oxidiser, to provide a purified water stream, and dispensing at least a portion of the purified water stream through a valve at a point of dispense as a dispensed stream; (b) stopping the dispense of the purified water stream by operating the valve to move between a dispense position and a recirculating position and recirculating the purified water stream as a recirculating water stream through at least a portion of the water purification apparatus including the oxidiser to provide a re-oxidised water stream; (c) measuring a conductivity value of the recirculating water stream prior to the oxidiser at a first location in the water purification apparatus that is prior to any ion-exchangers so as to provide a conductivity measurement of the recirculating water stream; (d) channeling the recirculating water stream from the first location to the oxidiser without passing through any ion-exchangers; (e) measuring a conductivity value of the re-oxidised water stream at a second location downstream from the oxidiser and prior to the re-oxidised water stream passing through any ion-exchangers; and (f) using the measurements to determine the TOC of the purified water stream of step (a) at the point of dispense of the purified water stream.