How to Install Washer Drain Standpipes

Shut off the water to your home at the meter. Unplug the washer from its outlet and scoot it out from the wall. Disconnect the hoses from the hot and cold water supply valves by unscrewing the couplings. If the couplings are hard to budge, use a pair of pliers.

Install a standpipe at least 2 inches in diameter to the P-trap, which connects to the drainage and vent system. Determine whether the washer trap is located underneath the washer or provided with the standpipe. If it is attached to the standpipe, install the standpipe so that the P-trap is 6 to 18 inches above the floor. The top of the standpipe should be 18 to 30 inches above the trap and a minimum of 34 inches above the floor or bottom of the washer, according to most building codes.

Insert the drain hose so that it slides no more than 8 inches into the drain standpipe. Secure the hose to the pipe with a beaded or nylon tie strap to prevent movement. Avoid tying the strap too tightly, which can disrupt proper airflow.

Install a standpipe adapter where the hose connects to the standpipe to minimize water leakage or splashing. Do not attach the adapter with tape or other adhesive materials, which can siphon off air and prevent waste water from draining properly into the washer trap.

Reconnect the hoses to the water supply valves and plug the washing machine back into the outlet. Restore water to the home at the main then check for leaks before operating the machine.