Spa Drain Assembly 1/2″ S w/ 3/4″ RB Adapter & Cap – 25212-004-000 The drain valve is mounted to the spa cabinet and allows a standard garden hose to gravity drain the water out of the spa. Drain valve has a 1/2″ slip body, 2 1/4″ face and a hole size of 1 5/16″. Includes 3/4″ straight ribbed barb adapters and cap.