A hemodialysis system according to an embodiment of the present invention includes a hydrochamber, and a water circuit for water to flow from an external water source into the hydrochamber via a water inlet valve. The hemodialysis system further includes a spent dialysate circuit for a disinfecting agent to flow to the hydrochamber via a recirculation valve during a disinfectant operation, and a drain valve disposed in the spent dialysate circuit. During the disinfectant operation, the hemodialysis system is adapted to replace a volume of the disinfecting agent exiting the spent dialysate circuit via the drain valve with an equal volume of water via the water inlet valve. The recirculation valve is directly connected to the hydrochamber such that in response to a pressure drop at the external water source, the disinfecting agent is prevented from backflowing through the water inlet valve.
