A peritoneal dialysis (“PD”) system having an air-aided pumping sequence is disclosed herein. In an example, a PD system includes a housing, a PD fluid pump housed by the housing, an airtrap, a fluid line extending from the airtrap, a fluid line valve positioned and arranged to operate with the fluid line, a gas line extending from an upper portion of the airtrap, and a gas line valve positioned and arranged to operate with the gas line. The system also includes a control unit configured to cause the fluid line valve to close, the gas line valve to open, and the PD fluid pump to pump gas from the airtrap into the gas line after a patient drain to create a pocket of gas in the fluid line and push residual used PD fluid towards a drain line.