Washing Machine Plumbing

Washing machine plumbing rough-inInstalling the plumbing connections for a washing machine is a fairly straight forward process, that a person of moderate "handiness" should be able to accomplish. In this article I will describe some basic rules, rough-in information and images to assist you, but if you encounter any problems along the way, just ask for help on the plumbing forum.

Tools and materials you may require

  • Basic carpentry tools
  • Soldering tools / PEX tools
  • Pipe, primer, glue (ABS/PVC)
  • Drainage fittings
  • Washer Box
  • Plumbing Permit may be required in your area

Washing machine plumbing rules

Clothes washer drains in Canada require a 2" trap and stand pipe if not draining into a laundry tray. In the US under the IPC(International Plumbing Code) the trap and standpipe must be 2".

A standpipe must extend at least 600mm (24") above the trap weir and terminate above the flood level rim of the washing machine(above the top of the washer).

A trap receiving the discharge from a clothes washer must be the removable type or have an integrated cleanout plug, as lint and sand are an issue that often clogs drains.

Washing machine plumbing installations

There are a few different methods for installing plumbing to a washing machine, depending on whether or not the room is going to be finished. You also have the option of draining the washing machine into a laundry tub or standpipe.

Washer Box rough-in with water hammer arrestorsIf your planning on having a finished laundry room then appearance is important; therefore, installing a washer box with all the plumbing hidden inside the wall is the best option. A washer box comes complete with a hot and cold faucet connection as well a stand pipe hole for the drain, easily mounting between wall framing members. Some washer boxes will also have water hammer arrestors built-in(see picture) to lessen the effects of water hammer caused by the fast acting washing machine solenoid valves.

A washer box is typically installed at a height of 42" from the floor to the bottom of the box, as long as that height is above the washing machine's flood level rim.

Washing Machine Drain Connection

washing machine drain - standpipeRegardless of whether your installing a standpipe or a laundry tray to drain the washing machine, you will need to locate and tie into an existing gravity drainage system and vent the trap.

  • Horizontal drains need to have a minimum grade of 1/4" per foot
  • Drain height for a laundry tray is 18-1/2" from the floor.
  • Trap should be removable or include an integrated cleanout.
  • Trap must be vented. If your connecting to an existing stack you may need to individually vent the washing machine and tie the vent in above the other fixtures draining into the stack.

Washing Machine water supply

Washing machines requires a 1/2" hot and cold water supply. The water supplies should terminate just higher than the washing machine to allow the hose connections to be seen, and easily shut off when required. Each water supply will require a 1/2" sediment faucet that the washing machine supply hoses will connect to and water hammer arrestors(see example picture).

Washing machine water supply

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