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How To Vent A Washing Machine Drain Pipe

Washing machine drain pipe vent.

Imagine you are doing a load of laundry and the washing machine starts flooding the laundry room floor. Additionally, the machine starts making some weird noises as it is working. Luckily, you’re there in time to turn off the water supply to the washing machine. Clearly, there appears to be a clog in the washing machine drain pipe. As you shut down the washing machine, you ask yourself is the pipe drain vented or clogged? Wondering how to vent a washing machine drain pipe? Install a standpipe that will connect to the P-trap. The standpipe then connects to the drain.

This is a great time to call out a professionally licensed plumber. Let’s take a look at what’s involved with a properly vented washing machine drain pipe.

Washing machine with water in it
Washing machine with water in it

How Does A Washing Machine Drain?

A washing machine may seem like it has a very easy operating system, when in fact, it is a little more complicated. When the cycle has finished, a pump pushes the water out of the tub. From there, it goes into a washer drain hose. This drain hose curves toward a standpipe in an upward direction. If you are not sure where the standpipe is, it is near the valves for the hot and cold water. If everything is working as it should, the water will go in an upward direction and into the standpipe. Then, the water heads out to the sewage line.

If there is an issue with the washing machine, it will not drain so the water can actually back up and end up on the floor.

Initial washing machine drain pipe hookups
Initial washing machine drain pipe hookups

What Is Needed To Vent the Washing Machine Drain?

If you need to vent the washing machine drain, there are the things you will need.

  • Standpipe – This is a pipe that is horizontal and angled 1/4 inch per foot towards the drain and foes from the drain to the washer.
  • P-trap – this is essential so that the water doesn’t sit. Another purpose of the P-trap is that it creates a seal so sewer gases don’t escape into the home.
  • Venting standpipe – this straight pipe vents the sewer gases and is usually vented through the roof
  • Cheater valves – these open up a valve so while water is flowing, air can go into the line. Check with local building codes to see if this is allowed.

Overflow Prevention Of A Washing Machine Drain?

Here are some tips to prevent an overflow of the washing machine.

  • A lint bag or garment bag helps prevent the building up of lint in the drainpipes.
  • Always clean the lint trap or filter in the washer
  • There should be at least 1/2 inch between the discharge hose and drainpipe to make sure the washing machine drains properly.
  • Using a detergent that is made for the washing machine is essential so there is no build-up of soap residue.
  • Drain pipes and hoses should be cleaned often.

How Much Does It Cost?

The cost will vary depending on what you need. Drainpipe replacement ranges from $230 to $1,140. A building permit may be needed and this ranges from $30-$150. Unfortunately, if you need to replace the washing machine, that will range from $350 to $1,200 depending on the size and style.

Other Recommended Maintenance

While you are learning how to vent a washing machine drain pipe, you will want to consider inspecting other plumbing areas of your home.

One of those is resetting the washing machine. If you have a Whirpool washing machine, you may find that you need to reset it. To do this, you can consult the owner’s manual or contact a plumber to do it for you.

Another area is choosing the right plumbing pipe. There are all different types of pipes for vent systems, draining, or waste and the correct one is based on temperature, location, durability, and cheapness of the material.

Lastly, you may find that your bathroom sink is clogged with hair. A great way to unclog it is to use baking soda and vinegar to help to loosen the hair and then you should be able to work the hair out.

Washing machine drain lines
Washing machine drain lines

When Do I Call A Professional?

If you are having issues with the washing machine such as water coming out, there is a bad smell, or it is making noises, it may be a good time to call a plumber. If you can find what is going on and fix it, this can save you money down the road.

Additionally, there are building codes that have to be followed to make sure the washing machine drain pipe is vented the right way. A plumber who is licensed can check on this for you to make sure the setup is correct so you have proper drainage from the washing machine.


A professionally licensed master plumber is essential to have to make repairs or updates in the home. Often it helps to get quotes from several plumbers. In addition, your local home inspection team can help with the inspection and also recommend a master plumber. Reach out to  ACE Preferred Inspections for a home inspection in the low country of South Carolina