How To Vent A Washing Machine Drain Pipe? All The Most Necessary Information!

The question is often asked how to vent a washing machine drain pipe. And now we will give you the answer to it.

Imagine a situation, suppose you heard strange noises coming from a washing machine drain pipe, and then the floor began to fill with water.

You react immediately and turn off the water. But there is still water left in the washing machine, and the drain pipe is clogged.

And you have a question, how to plumbing vent a washing machine drain pipe?

But how can I check how to vent a washing machine drain pipe?

You will need to install a riser connecting to the P-trap. And then the riser will connect to the drain system.

Now is the time to call a professional in this field – a plumber. Let’s further familiarize ourselves with what is associated with a properly ventilated drain pipe of a washing machine.

how to vent a washing machine drain pipe

The process of draining washing machines

Washing machines are very complicated systems. When the cycle is completed, the pump pushes the water out of the tub into the drain hose of the washing machine drain pipe. And the drain hose itself bends up to the riser.

The riser is located next to the air intake valve for hot and cold water. Thinking that everything has worked correctly, the water will begin its movement up and out into the riser itself, which in turn will divert the water.

If you have any problems during this process, the washing machine will not be able to drain, and drain water will accumulate and eventually seep into the laundry room.


Necessary for ventilation of the drain hole of the washing machine

Most often, for the washing machine drain pipe to work successfully, one of the following drains is required:

The riser is a horizontal drain pipe located from the drain to the washing machine, it is in a position at an angle of 1/4 inch per foot towards the drain.

The P-trap is necessary so that the water cannot stagnate inside. Well, it also creates a seal so that sewer gases cannot get into your house.

A ventilation riser is a straight pipe (most often ventilated through the other side of the roof) for the process of drainage of sewer gases.

Water inlet valve – specially creates negative pressure by opening the air admittance valve in order to let air into the pipeline. Be sure to read and familiarize yourself with local building codes and regulations, as this is not allowed by law everywhere.


How to prevent overflow of the washing machine drain?

If you follow the following preventive measures, you will be able to reduce the likely overflow of the washing machine opening.

  • Use clothes or lint bags, this prevents the abundant accumulation of lint inside the drainpipes.
  • Inspect and clean the lint catcher or washing machine filter.
  • The distance between the drain pipe and the washing machine drain hose should be at least 1/2 inch, this helps to ensure proper drainage.
  • The use of a special detergent is necessary so that soap residues do not accumulate.
  • Clean hoses and drain pipes frequently.

How to determine if the drainage pipe ventilation is bad?

The most frequent and widely known symptom of poor ventilation of drainage pipes is the unpleasant smell containing sewer gases.

It comes from your pipes.

Well, if the washing machine drain pipes can’t drain the water, the drain pipe is most likely clogged. There is also a possibility that the washer drain line is not ventilated, this leads to a slowdown in the discharge of water.

But it is much more likely that the drain is clogged or that it is not as big as new washing machines equipped with high-pressure pumps.


Unpleasant smell

Ventilation is more related to the protection of 2 inches of water being in the P-trap. There is a drainage trap under absolutely every sink in your house. Such traps hold up to about 2 inches of water every second to prevent unpleasant odors from entering your home.

If there is poor ventilation in your house, then the low pressure created by water flowing in one part of the house will be able to draw water from the rest of the drainage pipes.

Water that accumulates in the kitchen sink

If the washing machine drains the water, and it is poured into the kitchen sink, then this is probably a sign of poor drainage, which is from a poorly ventilated plumbing system.

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If there is poor ventilation in your house, you will probably hear gurgling when rushing water drains in another part of the house. This is due to changes in the air pressure in the pipeline.

Slow draining

In the most recent cases, the lack of ventilation leads to a slow drain of water from the plumbing. For example, the toilet slowly drains and fills to a minimum (well, it also loses water if you start another faucet).

In modern washing machines with high performance, no washing machine in some cases leads to flooding. Slow draining is due to clogging, not because of poor ventilation.


Operation of drain holes

The moment when water enters the sewer gas, it leads to the air, thereby creating a zone of vacuum or low air pressure in the drainage.

This can cause damage to your plumbing.

Drainage holes help to draw outside air into the water supply system. If the house is properly ventilated, the sewage odors remain trapped, and the system begins to merge without problems.

Often there are ventilation holes in the house, but they are relatively small. If you add several vents to the plumbing system, it will help improve the operation of premises with poor drainage.

Well, if the water accumulates, and later slowly drains, it indicates that you need to ventilate this.

Tools, possibly necessary for ventilation of the washing machine drain pipe

Usually, the addition of ventilation is required only in the case you have an old house that was not built following the code.

This task is exclusively for a professional, a jack of all trades – a plumber. And you will need something more than just tools.

The vent for your dryer is a completely different vent, it is different from the vent for the plumbing.


It is the name of the main drain pipe to which your washing machine is connected directly. It is a vertical or horizontal pipe. If it is horizontal, it should be tilted 1/4 inch per foot and directed to the main sewer line.

A vent pipe

It is a vent pipe that exits the P-trap and passes to an air intake air admittance valve, either to the attic or to the roof, to allow outside air to flow into the sewer.


It creates a water barrier directly between the house and the sewer line to prevent unpleasant odors in the house.

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When can I call a specialist?

If you often hear that your washing machine is noisy, there is an unpleasant smell from it, or water is flowing from there, you should immediately contact a specialist.

If you apply right away, it will save you money in the future.

To repair washing machines, you may need plumbing or cleaning of drain pipes. Calling a professional is the safest thing you can do, as it is often very complicated to fix it yourself.



Does a washing machine drain line need to be vented?

The washing machine drain pipe of our time has a large pump that drains water quickly. For such devices, a 2-inch drainage line is usually needed, as well as a properly vented water supply system. This helps prevent flooding, humidity problems, and unpleasant odors.

Does a washing machine drain need an air gap?

If water has started to flow out of the drain hose of the washing machine drain pipe frequently, then this is most likely due to clogging of the hose.

And if this is the problem, you will need to ventilate the drain hose, thereby ensuring air circulation.

There are a few ways to do this. Now we will get acquainted with them in more detail.

First, disconnect the drain hose from the washing machine and put it in a container or sink.

Using the plunger, start pumping air through the hose into the washing machine.
Again, disconnect the drain hose and blow into it. Thus, you will push air through the hose.

Next, add water to the washing machine box, and quickly disconnect the drain hose.

The water will start pushing air through the drain hoses.

Can I use a studor vent for a washing machine drain?

Vents will only help to banish the smell in the laundry room and humidity to a minimum. The air vent will help to reduce the need for cleaning after washing.

Can a washer and toilet share the same drain?

Yes, of course, it can.

In many houses, the sewerage is connected.


If your washing machine is broken, do not rush to try to repair it yourself, the washing machine can only hurt itself and in the future very much recoup on your wallet.

The best solution would be to call a specialist and rely on his help and correction of the situation.

And it is always important to remember that there are quite a lot of methods to ventilate the washing machine. You are not obliged to correct the situation in a frequently used way, it is important to rely on your model of the machine.

We really hope that our article was useful to you, we have selected only the most essential and interesting information for you. We wish you success!

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James Derrick

If you have become a reader of my blog, you are thinking about how to properly equip your home. I want to say that together with my family we live in our own big house.

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