A patient hydration system with an infusion subsystem which infuses fluid into a patient and a urine output measurement subsystem for measuring the amount of urine output by the patient. A controller is configured to control the infusion subsystem and is responsive to the urine output measurement subsystem. The controller includes a balancing function which controls the infusion subsystem to administer fluid infused into the patient to balance the urine output with the fluid infusion. The controller also includes a taper down function which controls the infusion subsystem to administer fluid infused into the patient at a rate less than the rate of urine output by the patient.