Basement Drain Backing Up When Washing Clothes? (Here's Why)

When you are washing your clothes, the last thing you’re expecting is the basement drain to back up. That is unless your basement drain continually backs up often when you do the laundry. This problem is more common than you might think. Luckily, there are a few things you can do that will stop your basement drain from backing up when washing clothes.

If your basement drain is backing up when washing clothes, the most likely cause is a blocked drainpipe. Watch the basement drain as you run the washing machine. If it overflows as the water is released, something is clogging either the line or the plumbing vent pipe. However, if there is no clear blockage, this could mean that you need to install a larger drain pipe.

It is bad news when your basement drain backs up, especially if there is carpet nearby. Let’s get to the root of the problem and fix your basement drain so that you can wash clothes without worry.

Several things can cause a basement drain to back up when washing clothes. Generally, a handy homeowner can easily remedy the problem, depending on the severity and the cause, and unclog the basement drain. Blockages are the most common cause for your basement drain backing up, and it is the easiest problem to solve.

The two main areas that can get clogged and lead to a backup are the drainpipe and vent pipe. If you cannot identify any blockage in either area, it could mean that your drainpipe is too small and needs to be replaced.

A blockage in the pipes between your washing machine and the basement drain can cause it to back up. When you wash your clothes, small fibers from your clothes can build up over time in the drain system. Also, just think of those tissues, change, and other small items that accidentally made their way from the dirty clothes pile to your machine.

If your drains are clogged for any of these reasons, you can get rid of these blockages by using a hose, drain bladder, Drano, a snake, or an auger.

In some cases, basement drains back up or overflow when the washer runs because too much water is exiting through the pipe at once.

Depending on the washing machine, it may use 30-40 gallons of water while running, which creates an enormous amount of pressure. A clogged pipe creates even more pressure as that water has trouble passing through. This increase in pressure and resistance can easily cause the basement floor drain to back up when washing clothes.

Old plumbing sometimes is not able to handle the rush of water from running a washing machine. When the pipes get overwhelmed by the large volume of water, it causes the basement floor drain to back up or overflow.

Basement drains that have even the slightest blockage are more susceptible to a high volume of water overloading them. If you carefully snake the pipe, you can usually remove the blockage easily and on your own.

Unfortunately, if your pipes are the problem, you may need to hire a plumber to make the fix. Inspect your pipes and measure their diameter. If your pipes measure 1 ¼”-1 ½” that is typically too small to handle the amount of water exiting a washing machine.

This means that you will likely need to get new pipes that can handle the water flow. Choose a drain line that is 2” in diameter, as it should handle the water from a running washer. Replacing drainpipes can cost between $200 and $1,000, but if your drainpipe is too small, it is necessary. Otherwise, you could experience water damage from your drain overflow. This means that you will also be tacking on these extra repairs to the bill.

While it may be far from your basement drain, a clogged plumbing vent pipe can cause it to back up. Your plumbing vent pipe is located on your roof, and it is integral to your home’s plumbing system. This vent allows air to flow through your pipes so your drains work properly. If this vent becomes clogged, it causes a vacuum and your pipes will drain very slowly.

Dust, leaves, debris, and even birds’ nests are common culprits for a blocked vent pipe. Because it is on the roof, you should get the help of a friend before attempting to remove the blockage.

If there is a sewer smell when your basement drain backs up, it could mean that the standpipe is dry. The standpipe is an elbow-shaped pipe that works like a P-trap for washing machines. When the drain and adjacent trap dry out, sewer odors can come out. Traps keep sewer gases and odor from seeping out because there is constantly water there as a barrier.

However, if the standpipe was recently dried out, sewer odors will come up and out of the basement floor drain. Sometimes, the water from the washing machine may be enough to replace the water in the trap. If not, all that you need to do is pour water into the drain, and the trap will be filled.

Most of the time, the water backing up from the washing machine will at the very least eliminate the sewer odor. The overflow will fill the trap, although you’ll need to use one of the above remedies to remove the clog and backup.

When your basement drain backs up when washing clothes, it is usually due to a blockage in the drainpipe. You can easily remove debris in the basement drain using a shop vac or using a snake or auger. Before using any plumbing tools, always inspect the drain with a flashlight in case the blockage is at the top.

If your drainpipe is fine, carefully inspect your plumbing vent pipe on the roof. Remove any blockages using an auger or a snake just like with a drainpipe. However, in some cases, the blockage is not the cause of your basement drain backing up when washing clothes.

Replacing drainpipes may be necessary if you cannot find any blockages in the line or in the plumbing vent. Contact a plumber if there is nothing apparent causing a blockage or if your drainpipe is only 1 ½” in diameter.

Regular check-ups from a plumber can prevent serious issues and will keep your basement drain in top shape.