How to Install Washer Drain Standpipes

Washing machines comprise a complex system of drains, valves, hose connectors and pumps to quickly and efficiently launder fabrics and clothing.
Standpipes installed above the maximum allowable height can hinder drainage, resulting in soggy clothes.Standpipes installed above the maximum allowable height can hinder drainage, resulting in soggy clothes.
One crucial component in this setup is the washer’s drainage system. Whereas some washers use laundry sink and floor drains to handle waste water, a drain standpipe hooks to the floor or wall next to the machine. Its job is to remove and direct dirty water from the washer basket to the P-trap connected to the machine.

Step 1

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.

Step 2

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.

Step 3

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.

Step 4

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.

Step 5

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.

Things You Will Need

  • Pliers (Optional)
  • 2-inch standpipe
  • Drain hose
  • P-trap
  • Standpipe adapter
  • Nylon or beaded tie strap


  • The top of the standpipe should be located above the machine‚Äôs highest water level, according to the experts at Black & Decker. If the standpipe is too low, gravity can cause water to overflow and spill onto the floor. If the standpipe is too high, water can flow back into the washer.
  • Improperly installed and clogged hoses can cause drain standpipes to malfunction. Avoid installing hoses that are too long for the standpipe. This can cause kinks and bends along the length of the hose.

About the Author

Based in Los Angeles, Bridgette Austin has been writing professionally since 2004. In addition to producing business publications for the nonprofit, accounting and technology industries, her work has also appeared on LIVESTRONG.COM, eHow and Austin holds a Bachelor of Arts in individualized studies from New York University.