Does the Washing Machine Drain into the Sewer Line?

You may not know where your washing machine’s wastewater goes, especially if you recently moved into a new house where it was never necessary to figure out where the washing machine drain goes. Knowing where it drains helps avert a lot of issues.

The washing machine often drains into the sewer pipe. The municipal sewer system receives wastewater from your home’s main drain through the sewer line. It can also drain in a floor drain, sump pit, or a utility sink. Ensure the drainage is safe to avoid flooding when using the machine.

If you are moving into or building a new house, you might also question where you can drain your washer without breaking local building codes. 

Washing machine drainage

Where does the water from my washing machine drain to?

Your washing machine’s wastewater is regarded as sewage and is normally emptied into the main sewer line that passes through your city or municipality. The waste is then transported to a treatment facility, where it is treated before being returned to the environment.

However, some residences have septic tanks and are not connected to a municipal sewer system. In these situations, the washing machine’s wastewater is drained into the septic tank, which is treated before being released into the environment.

Is it safe for washing machine water to drain into the septic?

Using a washing machine with a septic system is completely safe. Yet it would be wise to exercise some care. Various problems arise from putting too much gray water into your soak away from your waste drainage system. 

If you overload your drainage, you risk eradicating the good bacteria in your tank or perhaps causing a flood. Flooding from regular water is terrible enough, but flooding from wastewater is particularly unpleasant.

Where else can a washing machine drain?

A washing machine can also drain into one of the following services or systems in addition to a sewer line:

1. A floor drain

A floor drain is a drain on the ground level of a house or other structure. Wastewater from various fixtures and appliances, including washing machines, is collected in the floor drain, often connected to the main sewer line.

Usually, your floor drain can be found in the garage, basement, or laundry room.

2. A utility sink

A utility sink is a special kind of sink that is normally bigger than a standard sink and is used for tasks that require a lot of water, including washing clothes or cleaning up after pets. Utility sinks are typically found in the garage, basement, or laundry room and are composed of stainless steel or porcelain.

Most of the time, the utility sink is attached to the main sewage line. However, others are connected to a septic tank.

3. A sump pit

The basement of a house is typically where a sump pit is located. A sump pump is often attached to the sump pit, which collects the leaked water into the basement and pumps it into the main sewer. The sump pit may sometimes be joined to a septic tank.

Can I drain my washer into the yard?

“Gray water” refers to the water safely drained into your yard without extensive treatment. This includes water from your washing machine. Mix the water from your rinse cycle with the new water.

As a result, the number of chemicals in your washer’s water will be reduced. In other words, you can direct your washing machine water to a plant or grass that needs watering.

However, if you choose to do this, there are other considerations you should make. First, ensure you use soaps and detergents that are biodegradable and beneficial to the environment. The second thing you should check is that your washing machine drains into a part of your yard that won’t flood.

Also, you should be aware of any restrictions that may be in place concerning gray water drainage in your community.

Does a washing machine need a dedicated drain?

For your washing machine to drain correctly, you need a vented standpipe. Your washing machine cannot be installed properly without a dedicated pipe. A standpipe makes correct washing machine drainage possible.

Premature drainage, or when the water intended for washing your clothing rushes out of the machine too early, can be avoided with a separate standpipe for your washing machine. Moreover, backflow can be avoided with efficient washing machine drainage. 

Does a washing machine need a trap on the drain line?

If you install a waste pipe for any drain-requiring appliance, such as a washing machine, and the drain does not have a P-trap, you are at risk. Sewer gasses are effectively sealed inside the pipes by the pool of water at the bottom of the trap; if the trap is not present, the gases can directly enter your home.

Besides being full of dangerous organisms you can breathe in, some sewage gases, like methane, are also combustible. If the washer is in a closed space, leaving out the trap could provide a fire risk.

Why does my washer drain smell like sewage?

Your laundry area may smell like rotten eggs because of the following:

1. Parts of your washing machine have bacterial growth

Bacteria are mostly to blame for the smell coming from a washing machine drain and often cause many health issues. It is challenging to pinpoint precisely which component of the washing machine is contaminated because these germs cannot be seen in the pieces that make up the machine.

In such a case, simply run an empty cycle with a cup of vinegar or bleach to kill the germs. You should do this weekly. 

2. You overuse detergent

Excessive amounts of detergent might also make your washing machine smell like a sewer. A lot of detergent residue would be left after washing if you did not use enough water to wash your clothes.

Always use the recommended amount of detergent to avoid this. You find the amount in the washer’s soap tray or the manual. 

3. You wash your clothing in dirty water

Most people should already be aware of this because it is rather evident. If you wash your clothes in dirty water, the odor of sulfur will permeate your laundry area and washing machine, which is a pungent smell. Use only clean water to avoid a rotten-smelling washing machine.

4. It hasn’t been cleaned in a while

You shouldn’t count on your washing machine to smell fresh if you don’t frequently clean it and its components. Your washing machine may become clogged with clothing or insects, releasing an odor. To avoid bad odors, your machine should be cleaned frequently.

Can the sewer back up into the washer drain?

Sewage water may back up into your washing machine if your sewer line is congested or if the plumbing for your washing machine was installed improperly. If this happens, get in touch with a qualified plumber right away. Sewage backup in a washing machine can have several probable causes, and each must be dealt with immediately.

If a washing machine has backed up with sewage water, stop using it. A washing machine’s drain may cause additional drain blockages. Instead, have any obstructions in your plumbing checked out right away.

How to find out where washing machine water drains

The drain hose is located behind the washer. One end is attached to the appliance, and the other is inserted into a drain pipe that exits your home. When pulling the hose out of the pipe to check for obstructions, ensure it isn’t pinched or kinked anywhere.

You should most certainly eliminate any debris you detect. Finally, reassemble everything, restart the electricity and water, and try starting your washer once more.


Knowing where your washing machine drains will help you maintain your home’s plumbing and prevent potential issues. Most washing machines discharge into the sewage system before being treated by the city.

If you are unsure where your washing machine drains, speaking with a certified plumber is best. They will know the necessity to thoroughly examine your home’s plumbing and provide you with sound advice.

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