What is the minimum size for a washing machine drain?

Author: Lora Mills  |  Last update: Monday, April 7, 2025

The drain pipe should be a minimum of 1-1/2" I.D. (inside diameter) to ensure proper draining. The Washer drain hose is a 1-1/4" O.D. (outside diameter). To be confident that no siphoning of water will take place, the drain plumbing must be a minimum of 30" high for Top Load Washers.

Can I use a 1 1/2 drain for a washing machine?

Not fine. Too small (less than 2'' in diameter) and subject to flooding. Washing machines can pump out water faster than a 1-1/2'' pipe can drain which is why washing machines require either a 2'' drain stand pipe or a laundry tub with a 1-1/2'' drain pipe.

What is the code for a washing machine drain?

406.2Waste connection. 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.

Does a washing machine need a 2 inch drain?

The standard washing machine drain size is 2 inches, and the minimum requirement is 1 1/2 inches. Modern washers typically require a larger drain, and you may need a larger drain if it's connected to your kitchen sink.

How small can a drain pipe be?

No portion of the drainage system installed underground shall be less than two inch pipe size. EXCEPTION: Underground condensate waste, tub and shower traps and trap arms, and piping that receives the discharge from relief valves after an air gap may be normal size pipe less than 2-inches.

How To Install a Washing Machine Drain Stand Pipe - 2" Trap & Stand Pipe Height

What is the smallest drain size?

No trap or fixture drain shall be less than 1-1/4 inches, except as provided for in Section P904. 5. The fixture drains for water closets, trap standard service sinks and pedestal urinals with integral traps shall not be less than 3 inches.

Is 4 inch pipe enough for drainage?

A large diameter is useful for a drainage pipe because it can carry extra water. A 4-inch pipe can accommodate considerably more flow than a 3-inch pipe. Four- and 6-inch pipes are commonly used for French drains. Regarding speed, the 4-inch pipe is ideal for French drains.

What is the minimum washer drain?

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 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.

Can a washing machine share a drain?

The typical setup involves individual drain pipes leading to the main sewer line, ensuring each fixture has an independent pathway for wastewater. However, under the right conditions and with proper installation, it is possible for these two appliances to share a common drain.

What size is a washing machine waste pipe?

Washing machine / dishwasher waste outlet / drain hose pipe, sold by the metre (max 10m). Inside diameter approx 19mm.

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.

What size PVC pipe for washing machine drain?

The 1½-inch size is used to capture water that might flow out of a kitchen sink, a bathroom vanity or a tub. The two-inch pipe is commonly used to drain a shower stall or washing machine, and it may be used as a vertical stack for a kitchen sink.

Are drain sizes standard?

There are three common drain sizes for bathroom sinks, 1.25", 1.5" and 1 5/8 (1.625"). You need to select a drain that is the same size or SMALLER than the hole in your sink. For example, if you have a sink with a drain hole of 1.75", than any of the drains 1.25", 1.5", or 1.65" will work.

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.

Does a washing machine drain need a vent?

Eliminate Laundry Room Odors with Maplewood's Proper Drain Venting Services. All plumbing fixtures—including washing machines—must be vented.

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.

How long can washing machine drain line be?

The drain hose is approximately 1-1/4" in diameter. The standpipe or wall drain must have an inside diameter of 1-1/2" minimum and must be open to the atmosphere. The length of the supplied hose from tip to tip on a Top Load and Front Load washer is approximately 60".

What is the minimum space for a washer?

Standard side-by-side washer and dryer dimensions

For standard side-by-side washers and dryers, you'll need a space of about 56 inches wide for the set. If you have front load units, make sure to allow about four feet of space in front of the appliance for ample room to load and unload your laundry.

How high should a washer drain be above the trap?

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.

Why does a washing machine need a standpipe?

The standpipe is designed to prevent water from flowing back into your washing machine. To function correctly, the standpipe should be at least 34 inches tall, measured from the floor to the top of the pipe. This height is key to proper water flow and preventing siphoning, which can cause the standpipe to overflow.

What is the recommended minimum drainage pipe diameter?

Drain pipes for toilets and sinks should have a diameter of 1 1/4 to 1 1/2 inches. It's common for drain pipes in bathrooms and showers to have a diameter of two inches. Most toilet drain pipes have a diameter of three inches. Diameters ranging from 1 1/2 inches to 2 inches are typical for branch drain lines.

How deep to dig for a 4-inch drain pipe?

The trench should be about 18 inches deep and 9 to 12 inches wide.

Can I use PVC pipe for drainage?

From the ground up, PVC pipes are often used for drain, waste and vent (DWV) systems. These carry wastewater from buildings and homes, eventually connecting to the city's main or an on-site septic system. The larger pipes in the DWV system branch off into smaller pipes as they reach different areas of the structure.

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