How To Fix a Dishwasher That’s Not Draining

A dishwasher that won’t drain is a frustrating problem for any homeowner. Standing water in the bottom of your dishwasher likely smells and can cause damage if left unaddressed. Fortunately, many drainage issues can be resolved with simple do-it-yourself (DIY) solutions. 

Our guide explains the common causes of dishwasher drainage problems and provides step-by-step instructions on how to diagnose and fix the issue. Whether it’s a clogged filter, kinked hose, or faulty valve, we’ll help you get your dishwasher draining properly again.

Common Causes of Dishwasher Drainage Issues

Even the best dishwashers can have an issue from time to time. Several factors can contribute to a dishwasher not draining properly. The issue is likely the result of one of the following scenarios:

• Blocked garbage disposal or sink drain
• Clogged drain hose or filter
• Faulty drain valve or check valve
• Improper installation or connection issues
• Kinked or damaged drain hose

Tools and Materials Needed for Troubleshooting Your Dishwasher

Before you begin troubleshooting your dishwasher’s drainage issues, check that you have the following tools and materials:

• Bucket or large bowl
• Flashlight
• Owner’s manual for your dishwasher model
• Pliers
• Screwdriver set
• Towels or rags
• Vinegar and baking soda
• Wire hanger or plumber’s snake 

Pro Tip: Richard Trethewey, TOH plumbing and heating expert, reminds homeowners: “The cardinal rule before starting any plumbing project: Turn off the water.” Before you touch the dishwasher, shut off the water supply valve under the sink and cut power at the breaker panel.

How To Locate Your Dishwasher’s Model Number

You’ll need to find your dishwasher’s model number to access specific troubleshooting information and order replacement parts if needed. When you open the dishwasher door, the model number is typically located on one of the door panel edges, either on the side or top. Sometimes, it may be on a label inside the tub or on the back of the unit.

Once you’ve located the model number, write it down or take a photo for reference. This information will be invaluable when consulting the manufacturer’s website for troubleshooting guides or contacting customer support for assistance.

Checking the Drain Hose Connection

Let’s first check the drain hose. The drain hose is a critical component in your dishwasher’s drainage system. It carries water from the dishwasher to your home’s plumbing system. Inspecting this hose and its connections is often the first step in diagnosing drainage issues.

Inspecting the Drain Hose for Clogs

Take these steps to check for clogs in the drain hose:

1. Disconnect the hose from the sink drain or garbage disposal.
2. Inspect both ends of the hose for visible debris or blockages.
3. If possible, blow through the hose to check for obstructions.
4. Use a wire hanger or plumber’s snake to clear any clogs you find.

Remember to have a bucket ready to catch any water that may spill out when disconnecting the hose.

Addressing Kinked or Damaged Hoses

A kinked or damaged drain hose can significantly impede water flow. Inspect the entire hose length for any kinks, bends, or signs of damage. If you find a kink, try to straighten it out. If the hose is damaged, you’ll need to contact your dishwasher’s manufacturer to replace it. When replacing a drain hose, ensure it’s properly routed without any sharp bends that could cause future kinking. In some cases, you may need to repair PVC pipes connected to your dishwasher’s drainage system.

Pro Tip: When replacing a drain hose, don’t just route it directly from the dishwasher pump to the drain connection. As Richard from This Old House explains, “Any dishwasher manufacturer insists on one thing, a high loop. That means you run your hose to as high as you can get it right underneath your kitchen countertop height.” This high loop creates a column of water heavy enough to hold the check valve shut when the pump turns off, preventing dirty water and food particles from flowing back into the dishwasher.

Examining and Cleaning the Dishwasher Filter

If it’s not the drain hose, it’s time to check the filter. A clogged filter is one of the most common causes of dishwasher drainage problems. Regular cleaning can prevent many issues and improve your dishwasher’s overall performance. Check out our guide on how to deep clean your dishwasher.

When Richard Trethewey pulled apart a dishwasher on Ask This Old House, the filter area was packed with surprising debris — plastic container seals, food remnants, and what he jokingly called “the turkey leg of Christmas past.” As he demonstrated, all of that buildup was choking the small openings that water needs to pass through to drain properly.

Locating the Filter in Your Dishwasher Model

Filter locations vary depending on your dishwasher model. Most modern dishwashers have a removable filter at the bottom of the tub that you pull upward to remove. Some older models may have a self-cleaning filter system. Consult your owner’s manual if you have trouble locating the filter.

Step-by-Step Filter Cleaning Process

You’ll follow these steps to clean your dishwasher filter. Remember to do this regularly to prevent dishwasher damage and keep the appliance working as effectively as possible. Regular cleaning will also prevent odors in your dishwasher. 

1. Remove the bottom rack to access the filter.
2. Twist and lift out the cylindrical filter (if applicable).
3. Remove any visible food or other debris from the filter and surrounding area.
4. Rinse the filter under running water to remove smaller particles.
5. For stubborn buildup, soak the filter in warm, soapy water for at least 10 minutes.
6. Scrub gently with a soft brush if needed.
7. Rinse thoroughly and allow to dry completely before reinstalling.

Don’t Forget the Spray Arms: While you have the filter out, remove the spray arms and clean any food stuck in the spray holes. Use a toothpick or needle-nose pliers to dislodge debris from the holes — clogged spray arms can reduce wash performance and contribute to drainage issues.

Investigating Drain and Check Valve Problems

If the hose and filter are clear, the next step is to examine the drain and check the valves. These components are crucial in controlling water flow and preventing backflow into the dishwasher.

Identifying a Faulty Drain Valve

The drain valve is an electrical component that opens to allow water to drain from the dishwasher. To check the drain valve:

1. Unplug the dishwasher and remove the front access panel.
2. Locate the drain valve (consult your manual if needed).
3. Check if the valve’s arm moves freely when manually operated.
4. If it’s stuck or doesn’t move, you may need to contact the manufacturer for a valve replacement.

Troubleshooting Check Valve Issues

The check valve prevents drained water from flowing back into the dishwasher. To inspect the check valve:

1. Locate the check valve near the beginning of the drain hose.
2. Ensure it’s not stuck in the closed position.
3. Clean any debris that might be preventing proper operation.
4. If the valve is damaged or worn, it will need to be replaced.

If you feel out of your depth working with these components, it’s best to consult a professional.

DIY Solutions for Minor Dishwasher Drainage Problems

Before calling a professional, try these simple DIY solutions that can often resolve minor drainage issues.

Using Vinegar and Baking Soda to Clear Clogs

A combination of white vinegar and baking soda can effectively clear minor clogs. To do this, pour 1 cup of baking soda into the bottom of the dishwasher, followed by 1 cup of vinegar. Let the mixture sit for 20 minutes, then run a hot water cycle to flush the system. This solution can help dissolve minor blockages caused by food debris and freshen your dishwasher.

Manually Forcing Water Drainage

If your dishwasher still won’t drain, you can try manually removing the water:

1. Place towels around the dishwasher to catch any spills.
2. Use a cup or ladle to scoop out as much water as possible.
3. Use a wet/dry vacuum to remove remaining water, if available.
4. Run a short cycle to see if the drainage issue is resolved.

This method can help you determine if the problem is with the drain pump or elsewhere in the system.

Check Your Drain Hose Loop: One of the most common causes of dishwasher drainage failure is an improper drain hose installation. Every dishwasher manufacturer insists on a high loop—running the discharge hose as high as possible, right up to the underside of your kitchen countertop. Without that high loop, there isn’t enough weight of water in the column to hold the check valve shut, which allows food particles to travel back up the hose and cause clogs. If your hose runs directly from the pump to the drain connection without looping up, that short, low path is likely your problem. Securing the hose in a high loop with a couple of screws under the countertop is a straightforward fix that can solve both drainage and odor issues.

Pro Tip: Richard Trethewey, TOH’s plumbing and heating expert, explains that food particles and small debris are often the culprits behind drainage problems. Water and food particles drop down into the sump—a reservoir below the basin—where a grinder, much like a garbage disposal, grinds them up and sends them out to the drain. When that sump gets clogged with plastics or other debris, drainage stops. Start by cleaning everything you can find in there—Richard has pulled out everything from plastic container seals to old food remnants lodged in the impeller.

When To Call a Professional Plumber

While many drainage issues can be resolved with DIY methods, some problems require professional expertise. Consider calling a licensed plumber or appliance repair technician if:

• You’ve tried all the above solutions without success.
• There’s a strong sewage odor coming from the dishwasher.
• You notice water leaking from under the dishwasher.
• The drainage problem is recurring despite your best efforts.
• You’re uncomfortable performing any of the troubleshooting steps.

A professional plumber can diagnose complex issues and ensure that repairs are done correctly, potentially saving you time and money in the long run.

Preventive Maintenance To Avoid Future Dishwasher Drainage Issues

Regular dishwasher maintenance can help prevent many common drainage problems and extend your dishwasher’s lifespan. Establish a routine for cleaning your dishwasher’s filter. For heavy use, clean the filter weekly. For average use, clean the filter monthly. Don’t forget to remove large food particles before running the dishwasher cycle.

Best Practices for Loading Dishes

Proper loading can prevent debris from clogging your dishwasher. Here are some tips:

• Scrape plates thoroughly before loading.
• Avoid overloading, which can prevent proper water circulation.
• Ensure spray arms can rotate freely.
• Place larger items on the sides and back to avoid blocking water flow.

By following these practices, you can significantly reduce the risk of damage or drainage issues while helping the machine do a more thorough job at cleaning your dishes.

Troubleshooting Other Common Dishwasher Problems

While drainage issues are common, dishwashers can experience other problems as well. Here are some quick tips for addressing other frequent issues:

• Dishes not getting clean: Check spray arms for clogs and ensure you’re using a detergent compatible with your dishwasher type.
• Leaks: Inspect door gaskets and hose connections for wear or damage.
• Dishwasher not starting: Verify power connection and door latch functionality.
• Unusual noises: Look for misplaced utensils or damaged spray arms.

Remember, regular maintenance and prompt attention to minor issues can prevent more significant problems down the line. If you’re dealing with persistent leaks or overflow issues, consider installing a washing machine drain pan under your dishwasher for added protection.

Our Conclusion

A dishwasher that won’t drain can be a nuisance, but it’s often a problem you can solve yourself. Checking the drain hose, filter, and valves will often help you spot the issue. Regular maintenance, such as cleaning the filter and proper loading practices, can prevent many problems before they start.

If you’ve tried these DIY solutions without success or feel uncomfortable performing any of the troubleshooting steps, don’t hesitate to call a professional plumber or appliance repair technician. They have the expertise to handle more complex issues and can ensure your dishwasher is operating safely and efficiently.