Washing Machine Causes Drain To Overflow

At the end of a long day, the last thing that you want to find after doing some laundry is a giant puddle of water all over the floor.

Washing machine drains will often overflow because of a clog in the drain standpipe, or the standpipe itself is too small in diameter to handle the amount of water being forced through it. More times than not, the problem is from a clog. Simply snaking the standpipe and or using an enzymatic cleaner product will unblock the clog, allowing the water to drainproperly. 

Depending on how big of a clog you have, you could have a large mess. Most high-efficiency washing machines use between 15 to 30 gallons of water per load. Older washing machines could use between 30 to 45 gallons per load. That’s a lot of water to clean up if you do have a clog in the drain pipe.

How a Washer Drains

Before we get into what is causing the drain to overflow, let’s take a quick look at how a washer drains.

When the washing machine is washing, the drain pump motor spins counterclockwise and allows the water to recirculate into the machine. When it’s time to drain, the water fills the drain pump, and the motor reverses direction to force the water into the drain hose. As the pump sucks in the air from the drained washing machine, it uses the air pressure to force the water up the drain hose and out of the machine. The water finally exits the hose down a standpipe connected to a laundry sink or connected directly to the home’s drain system, which leads to either a septic tank or the public sewage system.

How To Diagnose The Problem Yourself

To diagnose the problem, you will first need to fill the washing machine with water. Next, turn the dial to the drain setting. Before you begin draining, make sure that you are in a position where you can see down into the standpipe and still have access to immediately shut off the washer once the drain begins to overflow.

What you are looking for while the water begins to drain is to see how long it takes before the water begins to overflow. For example, if the water begins to pour out of the drainpipe right away then you know that the clog is likely to close and could be removed using a small drain snake. If it takes a bit of time before the drain overflows then you know the clog is further down the drainpipe and would require a larger drain snake to clean-out and clear the obstruction.

How To Unblock a Washing Machine Standpipe

If you’re washing machine drain is overflowing, then you might have a clog in the standpipe where your drain hose gets connected. To unclog it follow the steps below.

Step 1 – Remove the drain hose

Before you remove the drain hose from the standpipe, you should first make sure that the washing machine is turned off. To remove the drain hose, you will most likely have to cut off the zip tie that is holding it firmly to the standpipe or some other type of pipe nearby.

Step 2 – Try a garden hose

Try taking a garden hose and sticking it down in the standpipe, turned on all the way. Although this will probably not unclog the debris, it will help confirm that the clog is in fact in the standpipe and not in the washing machine drain hose.

The reason that the garden hose will probably not unclog the debris is that when a washing machine is pumping out the wastewater, it is traveling with 2 to 3 times more pressure then the garden hose could produce. So if the washing machine pressure couldn’t unclog it, the garden hose will most likely not either.

Step 3 – Snake the pipe

Take a drain auger and feed it down into the pipe. Keep pushing the snake into the pipe until you can feel some resistance. Then, rotate the snake against the blockage until you can feel it give way and allow the snake to continue to feed in smoothly. Pull out the snake and hopefully what was causing the blockage will be pulled out with it.

If snaking the pipe doesn’t do the trick, you can try using Drano or Liquid Plunger to break away the clog. Follow the instructions on the package so you know how long you should leave the chemicals down the drain before you flush it out.

Step 4 – Run water

Using the garden hose again, run water down into the standpipe for a couple of minutes to make sure that the blockage has been removed. Often the clogged object will become attached to the snake and come out, but other times running the water down the drain after will help remove it.

How Do You Unclog a Washing Machine Drain Pipe?

Now and then your washing machine drain pipe could become clogged from dirt, lint, and hair, which will prevent water from flowing through. The good news is that this is fairly easy to fix on your own.

Before you get started to make sure that the washing machine is turned off.

Step 1 – Locate the drain hose

Locate the drain hose in the back of the washing machine. This hose is normally located near the bottom of the machine, and it is generally black. If you follow the hose, it should either lead to a laundry sink, standpipe, floor drain or directly into a PVC pipe.

Step 2 – Disconnect drain hose

Using a pair of pliers, pinch the clip that is holding the drain hose to the washing machine. While squeezing the clip, you should be able to pull the drain hose free.

Washing machine Hose Clamp

Also, remove the other end of the hose from where it is connected to. For example, it could be set up to drain into the laundry sink or a PVC pipe connected to the laundry sinks plumbing. You may need to cut off a zip tie that could be holding it securely in place.

Step 3 – Remove the blockage

Using a long metal coat hanger or an auger, remove any debris caught in the drain hose. Next, take a garden hose or a bucket of warm water and flush the drain pipe. Straighten the hose and take a flashlight to look through to see if the debris has been removed.

If the clog is big enough, you might need to use a chemical cleaner to help break away the debris.

Once the drain hose is cleared, take your flashlight and look inside of the drain discharge connector on the back of the washing machine. While wearing some rubber gloves, stick your finger in to see if there is anything else blocking the hole, and to pull out any sludge type debris caught inside.

Step 4 – Hook the hose back up

Once you are satisfied that the hose is clear of any debris, you can now re-install it to the back of the washing machine. Again take your pliers and squeeze the metal clip so that you can slide the hose back into place. Once the hose is pushed on as far as it’ll go, let off on squeezing the clip so that it tightens. Give the hose a little tug to ensure that it is attached nice and tight.

Next, place the other end of the hose back where it came from.  Use a zip tie to secure it so that it doesn’t come loose and fall off. If it does, you’ll have a big wet problem to clean up.

What Causes Washing Machine Drain To Overflow?

Aside from having a clogged standpipe, there are a few other reasons why your washing machine drain might overflow, and some of the other most common reasons are:

  • Kinked discharge hose.
  • Drain pipe, not the proper size. The inside diameter of the drain pipe should be a minimum of 1½”. The outside diameter of the drain hose attached to the washing machine is 1¼”. The reason you want to have the drain pipe slightly larger is to allow for ventilation. Increasing the inside diameter of the drain pipe to 2″ might help more.
  • Drain hose from washing machine pushed too far down into the drain pipe. You should only have the flat smooth part of the hose sitting in the drain pipe, which is 7″ long.
  • Missing P-trap. The P-trap is used to block sewer odors from coming up through the pipe and into your home, but the P-trap is also used to help move water smoothly through the pipe. Without a P-trap, the water might take a little longer to flow through which could cause a backup.

Does Washing Machine Drain Hose Need Elevated?

The washing machine drain hose needs to be elevated at least 30″ to 3′ from the base of the washer for it to function properly. Without having the drain hose located high enough, gravity will take over and the water filling the washing machine will run out of the hose and into the floor drain.

If your drain is not at least 30″ from the base of the washer, you can use an anti-siphon clip to attach the hose to the back of the washer. The anti-siphon clip will elevate the drain high enough to reach the 30″ height requirement.

How To Prevent Drain Pipe From Overflowing

  1. Install a laundry sink – If you don’t already have a laundry sink, you should think about getting one. Draining from the washing machine into your laundry sink will allow you to use a mesh lint catcher over the end of your drain hose. The lint catcher will help prevent fabrics, lint, hair, and other material from making its way down your drain pipe. You will need to keep an eye on the lint catcher and frequently clean it as overtime it will begin to clog itself and become a whole other problem.
  2. Buy a high-efficiency washing machine – High-efficiency washing machines use a lot less water than a standard washer, therefore limiting the amount of water behind sent down the drain. If the drain does clog, the water should fill up in the laundry sink before it overflows from the standpipe.
  3. Regularly snake your drain – Depending on how frequently you use your washing machine, try to snake your drains every few months, or when you start to notice water draining much slower.
  4. Baking soda and hot water – Every so often, try pouring a full kettle of boiling water down the drain, followed by a cup of baking soda. Next, pour a mixture of 1 cup of vinegar and 1 cup water down the drain and cover with a drain plug. Let that sit for about 10 minutes before pouring another full kettle of boiling water down the drain.

Can You Put Drano In Washing Machine Drain?

Drano is safe to use in your washing machine drain to help eliminate a clog. If you are going to use Drano, you need to make sure to run an empty load right after using it to help flush out any remanence of Drano from the washing machine drain and plumbing.

Drano can cause damage to PVC piping if left sitting for too long as it will soften the plastic piping and eat away at the PVC glue used to connect the pipes.

Please be advised, that because Drano is a chemical, you should also be careful while using it that you do not get any on your skin or breath it in as it can also be harmful to your lungs.


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