A peritoneal dialysis system includes a control unit configured to cause (i) a fluid inlet valve and a fluid outlet valve to occlude a fluid inlet line and a fluid outlet line, respectively, while a linear actuator moves a piston to create a positive pressure within a pump housing, the positive pressure measured by a pressure sensor, and (ii) the fluid inlet valve to occlude the fluid inlet line and the fluid outlet valve to open the fluid outlet line, while the linear actuator moves the piston so as to maintain the positive pressure within the pump housing while fluid is pumped out of the fluid pump chamber via the opened fluid outlet line.

A pump device includes a supply chamber having a supply-side accommodation part; a drain chamber having a drain-side accommodation part; dividing membranes each being a flexible member that closes a corresponding one of the supply-side accommodation part and the drain-side accommodation part, the dividing membranes displaceable relative to the supply-side accommodation part and the drain-side accommodation part to cause dialysate to be suctioned into and discharged from the supply-side accommodation part through a liquid-supply-side connection port and cause drain liquid to be suctioned into and discharged from the drain-side accommodation part through a liquid-drain-side connection port; and a pump body from which the supply chamber or the drain chamber is detachable and attachable with the supply-side accommodation part or the drain-side accommodation part being closed by the corresponding dividing membrane, the pump body including a piston to move with activation of a motor and to displace the dividing membranes.

A peritoneal dialysis system includes a chamber, a hydraulic pump including or operating with a hydraulic fluid storage area, an inflatable bladder located within the chamber and in hydraulic fluid communication with the hydraulic pump, and a control unit configured to cause known amounts of hydraulic fluid to be reuseably (i) pulled from the inflatable bladder into the hydraulic fluid storage area in a draw stroke in which fresh or used dialysis fluid is pulled into the flexible container, and (ii) pushed from the hydraulic fluid storage area into the inflatable bladder in a discharge stroke in which fresh or used dialysis fluid is pushed from the flexible container.