A dialysis system for determining an amount of total chlorine in a partially purified water sample is disclosed. The system includes a water machine that produces at least partially purified water including an at least partially purified water sample and a dialysis machine that provides a dialysis treatment to a patient. The dialysis machine receives the at least partially purified water from the water machine to prepare dialysis fluid for the dialysis treatment. The system also includes a total chlorine detector configured to receive the at least partially purified water sample, at a first time apply a source voltage to the at least partially purified water sample, and at a second time stop applying the source voltage to the at least partially purified water sample and instead monitor a sensed electrical parameter to determine an amount of total chlorine in the at least partially purified water sample.