A dialysis system includes a dialyzer, a sorbent cartridge configured to clean used dialysate from the dialyzer, a dialysate pump actuator configured to pump dialysate to the dialyzer, and a conductivity sensor located adjacent to a temperature sensor. The dialysis system also includes a disposable cassette configured to carry dialysate pumped by the dialysate pump actuator. The disposable cassette includes a combined conductivity and temperature sensor fluid chamber separate from the conductivity sensor and the temperature sensor and located so as to operate with the conductivity sensor and the temperature sensor, respectively, when mounted for operation.