Dirty Water in Washing Machine: common causes and How to fix5 min read

A functioning washing machine should drain out dirty water, but occasionally homeowners find excess dirty water in their washers. Whilst there are a number of potential causes, there are many at-home solutions without the need to pay for an expensive plumber. 

Dirty water in a washing machine is most often caused by back siphoning where dirty water re-enters the drum. This is due to faulty installation, a kink in the drain hose, or a drain blockage. Clear blockages and ensure the drain hose is in the correct spot. Another possible cause is clogged internal components. 

While it may seem alarming at first glance, this is actually a common issue that can be caused by a variety of factors. With the proper diagnosis and a few simple repairs, you’ll be able to get your washing machine back up and running in no time. Let’s jump into the details and find out how to get rid of dirty water in the washer.

Why Does Your Washing Machine Have Dirty Water in It? 

The most likely cause of dirty water appearing in your washing machine is back siphoning. Back siphoning is a plumbing problem that occurs when dirty water flows back into the clean water supply and it can lead to dirty water appearing in your washing machine. 

For example, when you use your washing machine, it drains dirty water through a drainage hose that is connected to the plumbing system. If the drainage hose is plumbed incorrectly or if there is a problem, contaminated water can flow back into the washing machine. 

The other potential cause of dirty water in the washer relates to components within the washing machine. If the drain, filter, or pump are faulty this could cause dirty water to appear in the washer. If your washing machine is leaking oil into the tub this could also cause dirty water.

It’s easy to assume, like I have in the past, that dirty water is caused by dirty clothes and that cleaning your machine will fix the issue. However, dirty water will continue to come back unless you address the root cause and in this article, I’ll talk you through exactly how to fix it. 

The most common cause: Back Syphoning 

Unfortunately, the most common cause of dirty water in the washing machine is due to faulty installation. 

A faulty installed or blocked drainage can allow drainage water from the washing cycle to backflow into the washer. If the standpipe (which is where dirty water drains into) is clogged, it’s possible for dirty water to back up into the washer. 

If your washing machine waste pipe connects to the spigot trap under your kitchen sink it’s also possible that dirty sink water is entering your washing machine. This could be caused by the washing machine hose not being installed in an upwards loop down into the spigot trap. 

Put simply: The hose needs to be raised above the sink trap to prevent sink water from flowing down the pipe and into your machine. 

Here are some common signs of back siphoning: 

  • After the cycle, your washer partially re-fills with dirty water over an extended period of time even when turned off
  • The wash may take longer and spinning may not be as effective
  • The water may be greasy with a pungent smell (this is likely to be sink drain water)

A faulty drain hose allows water from the washing cycle to backflow into the washer, contaminating the clean water in the machine. This can happen if the drain hose is poorly installed, clogs up, or develops a kink or blockage.

At this stage, you might be thinking of phoning a plumber or your washing machine manufacturer but it’s worth noting: If your washer is under guarantee most manufacturers will not pay for this work since it’s due to a faulty installation. So I’ve given simple steps below on how to fix it. 

How to prevent back siphoning 

The first thing you should do is locate the problem: have you got a blocked standpipe or is your washing machine hose installation at fault? 

If you have a blocked standpipe you’d notice things like: 

  • Water backs up into the sink
  • The sink is slow to drain
  • A bad odor comes from the drains
  • Gurgling sounds when draining 

The easiest way to clear a blocked drain is to either put boiling water down the drain or use a drain clog remover (on Amazon). If this doesn’t work you’ll need to get more physical and use a plunger, then a drain snake (on Amazon)

Once you’re certain your drain isn’t clogged, turn your attention to the grey drain hose behind your washing machine. You’ll need to ensure the hose goes up over the height of the sink bowl, and down again before it meets the trap. Washing machines come with the support crook accessory and this can be used to ensure the hose stays in place.

Washer drain hose into trap
This image shows how a drain hose should correctly be plumbed into the trap, and is therefore moving downwards into the drainage system.

I found this useful video talking you through how to plumb in a drain pipe: 

Hopefully, by checking for any drain blockages and by re-positioning your drainage hose, I’ve helped you prevent an airlock and any kind of dirty water from returning to your washing machine.

If this hasn’t helped, however, there may be an internal issue with the machine itself. Next up I’ll walk you through the other potential causes of dirty water and some actionable steps you can take to prevent it.  

Internal Problems with the washing machine

There are a number of potential problems within the washing machine that can cause dirty water to appear in the drum. These problems range from faulty internal components such as blocked drains and malfunctioning pumps to dirty inlet valves. I’ll explain each potential cause and then 5 steps you can take to rectify the situation. 

Blocked Drain

A blocked drain can cause dirty water in your washing machine as the water won’t be able to flow out of the machine. A blockage can be caused by lint, hair, soap scum, or other items stuck in the drain pipe. 

This can build up water in the machine and result in a contaminated wash cycle. If the water can’t flow from the machine, it won’t go through its normal cycle. Therefore, dirty water will remain in the machine.

Dirty Water Inlet

A dirty water inlet can allow sediment, dirt, and other contaminants into the washing machine with the water. These contaminants can then be circulated through the washing machine, causing the water to become dirty. 

Clogged Inlet Filter

A washing machine inlet filter prevents debris from entering the internal parts of the washing machine. It filters dirt, lint, coins, buttons, and other foreign objects from entering the water inlet valve. 

When clogged, it prevents the machine from taking in fresh water from the water supply. This means the washer will constantly recirculate the water inside, causing it to become dirty and contaminated. 

The clogged inlet filter can also lead to the machine not spinning correctly, resulting in soapy water and dirt particles remaining in the washer. This can make the water appear murky and dirty when washing a load of laundry.

Malfunctioning Pump

The pump takes water from the source, like a faucet, and then pushes it into the washing machine. It also pumps the water out of the machine at the end of a wash cycle.

If it isn’t working correctly, it may not draw in the water appropriately or fail to push out the dirty water after a wash cycle at the right rate. This may lead to the dirty water remaining in the washing machine, causing clothes to come out with a dirty or soapy residue.

5 steps to cleaning your washing machine to prevent dirty water

Here’s how to get rid of dirty water in your washing machine in a few easy-to-follow steps:

Step 1: Unplug the Washing Machine and Drain It

Your first step should be disconnecting the washing machine from power and turning off the water supply to prevent electric shock or flooding. To remove the water in the washer, you can use a garden hose to siphon it.

Alternatively, you can remove the filter and let the water flow through the drain pipe or use a bucket to scoop it out.

Step 2: Remove and Clean the Filter

Take out your washing machine’s filter and clean it thoroughly. If you notice any holes or cracks on it, replace it, as they limit the filter’s ability to trap dirt and debris. Remember to always give the filter a deep cleanse every three to four months.

Step 3: Clean the Inside of the Washing Machine

Make a mixture of one cup of warm water, a tablespoon of white vinegar, and a drop of soap, and use it with a brush to scrub the inside of your washer. This will help you easily remove the debris that has built up in the machine.

Step 4: Clean the Drain Hose

Use a pair of pliers to loosen the hose clamp at the end of the drain hose. Pull the drain hose off the washing machine and inspect it for any blockages or debris.

Use a hose brush or old toothbrush to clean the drain hose, then rinse it thoroughly with clean water. Reconnect the drain hose to the machine and tighten the hose clamp.

In some cases, the drain hose may not be clogged but kinked. This allows the build-up of debris, leading to discolored, cloudy, brown, and dirty water from your washing machine. Replace the drain hose if you spot any bends or kinks, as it’s hard to get it to work efficiently again once it’s bent.

Step 5: Clean the Water Inlet

A dirty water line can make your laundry water filthy and unsafe. In addition to this, a clogged water inlet valve can cause your washing machine to leak during the fill cycle.

Run water down the drain pipe to clear off dirt and debris in the water inlet. You can also use a drain snake to eliminate debris accumulated in the water inlet.