What is the plumbing code for a washing machine drain pipe?

Author: Prof. Oscar Watsica MD  |  Last update: Monday, July 14, 2025

The waste from an automatic clothes washer shall discharge through an air break into a standpipe in accordance with Section 802.4. 3 or into a laundry sink. The trap and fixture drain for an automatic clothes washer standpipe shall be not less than 2 inches (51 mm) in diameter.

What is the code for washing machine drain pipe?

According to the Universal Plumbing Code, the standard drain size for a washing machine is 2 inches. The absolute minimum should be about 1 1/2 inches. However, keep in mind that wash load capacities can vary by up to 400% or more depending on the model.

What are the rules for washer drains?

In order for the drain hose on your Top Load Washer to function properly, the drain must be at least 30" up from the floor and less than 8 feet high. In order for the drain hose on your Front Load Washer to function properly, the drain must be at least 24" up from the floor and less than 8 feet high.

What is the standpipe code for washing machines?

804.1 Standpipe Receptors.

No standpipe receptor for a clothes washer shall extend more than 30 inches (762 mm), or not less than 18 inches (457 mm) above its trap.

What are the requirements for a washing machine standpipe?

Your laundry standpipe must extend past your washer's overflow line, typically reaching a height of 30-36” or 18”-30” above the trap.

Washing machine drain line rough in explained. [Just over 2 minutes] North Carolina Code.

Does a washing machine waste pipe need to be high?

The drain hose should be connected to the standpipe at the correct height for it to work properly. Ensure the highest point of the water drain hose is a minimum of 40cm and a maximum height of 100cm from the floor.

What is the minimum size for a standpipe?

Standpipes shall be at least 4 in. (100 mm) in size. Standpipes that are part of a combined system in a building that is partially sprinklered shall be at least 6 in. (150 mm) in size.

What is the height of the drain pipe for a top load washer?

The discharge height MUST NOT BE LESS THAN 30 INCHES and no more than 8 feet above the base of a Top Load washer. Note: If the drain is not 30" high, use the Drain Hose Clip (sometimes called an Anti-Siphon Clip) provided with the Top Load washer install kit to lift up the drain hose.

Does a washer standpipe need a vent?

All plumbing fixtures—including washing machines—must be vented. Improperly vented drains can be sluggish and noisy, and can emit hazardous fumes. Properly vented drains allow the P-trap to do its job: prevent sewer gases from escaping into your home.

How to plumb in a washing machine waste pipe?

There are three ways of connecting the waste pipe, as follows:
  1. Push fit waste: Simply join the connecters together after removing any burrs.
  2. Compression waste: Cut and sand the pipe, then use a rubber washer and nut to connect the pipe.
  3. Solvent weld waste: Again, cut and sand the pipe.

Does a washing machine drain need an AP trap?

Install a P Trap

A P trap is a necessary part of the plumbing for a washer. It's a U-shaped piece of piping between the appliance and the sewer line. After water drains out of the washer, the P trap's shape holds enough water to create a barrier between the house and the sewer line.

How long can a washing machine drain pipe be?

Ideally you should extend the plumbing to the appliance, for both water supply and drain waste. But if absolutely necessary you can extend your waste drain hose to a maximum of three (3) metres, providing the use of the correct bore size, type, and quality of hose, and suitable joining pieces are employed.

Do I need a standpipe for a washing machine?

Some manufacturers recommend a standpipe, and some water companies insist on it. The easiest solution though, is to put your machine next to a sink and change your sink trap to a washing machine trap – which has an inlet for the waste hose above the trap.

Can a sink and washing machine share the same drain?

Yes, with a Y-fitting, you can successfully connect a utility sink and washing machine to the same drain.

How do you vent a washing machine drain pipe?

How do you vent your washing machine?
  1. Hire a plumber to vent the washer for you. Believe it or not, a lot goes into venting a washing machine drain pipe. ...
  2. Run the drain pipe into an existing vent stack. ...
  3. Install a P-trap. ...
  4. Add an air admittance valve (AAV).

What is code for drain height?

Discharge/drain hole (vertical): 16-20 inches from floor. Fixture (side to side buffer): 15 inches minimum from centerline, 20 inches recommended. Fixture (front buffer): 21 inches minimum to nearest obstruction, 30 inches recommended.

What are the requirements for a washer standpipe?

The standpipe for the clothes washer must be trapped. The standpipe height should be at least 18 inches (457 mm) and no more than 42 inches above the trap weir.

What is the code for a washing machine standpipe?

UPC 804.1 Standpipe Receptors.

No standpipe receptor for a clothes washer shall extend more than 30 inches (762 mm), or not less than 18 inches (457 mm) above its trap.

What size pipe for a washing machine drain?

Answer: The minimum 2-inch drainage pipe is used for the standpipe, trap, trap arm to the vertical vent or waste stack and also for the vertical vent. As soon as the drainage pipe turns horizontal from the vertical vent or waste stack, the minimum drain pipe size for the horizontal drain is to be 3 inches.

What is the height of the standpipe for a washer?

❖ A standpipe is typically used for capturing the waste flow from a pumped discharge plumbing appliance such as a dishwasher or a clothes washer. An 18-inch (457 mm) minimum height standpipe provides a small volume for accumulation of waste flow above the entrance to the trap.

How do I stop my washing machine drain pipe from smelling?

The Fix: Pour about a gallon of water down the pipe. If you're dealing with a dry p-trap, this should fix it. If you still smell sewage, call a plumber to make sure it and your drain pipe have been properly installed.

What is the washing machine drain pipe called?

A washing machine drain pipe, also known as a drain hose, is a flexible tube used to expel used water from a washing machine to a dedicated drain system. The washing machine drain pipe is an essential component of any household laundry system, ensuring efficient and safe removal of water post-wash.

What is the pitch for a washing machine drain?

The drain for either of these must slope down at a rate of 1/4 inch per running foot. Many washing machines are self-leveling.

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