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Q: I just opened the dishwasher door to find the bottom of the unit filled with dingy water. My first thought was that the cycle didn’t finish so I ran the dishwasher again, but that didn’t help. Why is my dishwasher not draining? Is this a do-it-yourself fix, or do I have to call a plumber?
A: You did the right thing running your unit a second time. If it gets inadvertently shut off during a cycle, there’ll be standing water in the dishwasher bottom when you open it. When that smart move doesn’t solve the issue, the problem lies elsewhere. Dishwasher service calls are common in the plumbing industry, but fortunately, the fix to a dishwasher not draining is often something simple you can do yourself. Before you call a pro, troubleshoot your dishwasher by following these steps.
Determine the type of dishwasher drain connection you have.
The first step in troubleshooting a dishwasher that’s not draining is pinpointing the type of drain connection beneath the sink. Open the cabinet and look at the configuration of the corrugated dishwasher drain hose and how it connects to the sink drain. The following drain connections are the most common.
- High loop to disposal: In this configuration, the dishwasher drain hose will enter the cabinet from the dishwasher—loop to the top of the cabinet, where it’s held in place with tape, a string, or a chain—and then connect to the garbage disposal.
- High loop to drain: If no garbage disposal is connected, the dishwasher drain hose should still have a high loop, but it will then connect to the drain pipe. The connection must be before (above) the P-trap on the drain line. Sewer gases can enter the dishwasher and leave a stinky smell if it isn’t.
- Air gap to disposal: In this configuration, the hose runs to the top of the cabinet just as in the high loop, but instead of having a tape or chain to hold it in place, the hose connects to a fitting at the back of the sink. If the dishwasher drain connection has an air gap, a small cylindrical knob will be installed on the sink’s top to allow air to enter and prevent dirty sink water from draining back to the dishwasher. In essence, an air gap is like a dishwasher overflow that prevents air locks in the hose.
- Air gap to drain: This is the same configuration as air gap to disposal, just minus a garbage disposal. The hose will run to the air gap and then connect to the drainpipe before the P-trap.
Run your garbage disposal.
The drain hose from your dishwasher empties into the garbage disposal drain. If the disposal unit contains unground food, or food sludge has settled in the drainpipe below the disposal, it can prevent even the best dishwasher from draining properly. Sometimes, running the disposal is all it takes to get the dishwasher draining again.
In fact, it’s a good idea to get in the habit of leaving the water on and letting your garbage disposal run an additional 15 seconds after the food is gone. This clears all remaining food that might otherwise remain in the P-trap drain beneath the disposal.
RELATED: 9 Tips for Keeping Your Garbage Disposal in Top Shape
Remove standing water in the bottom of the dishwasher.
If running the garbage disposal doesn’t help (or you don’t have one), it’s time to drain the water in your dishwasher so that you can take a closer look at what could be causing the problem. Place absorbent towels around the base of the dishwasher and then remove the bottom dish basket by simply sliding it out. With the basket out of the way, use a plastic cup to scoop the dirty, foul-smelling water into a bucket for disposal. When the water level is too low to scoop, use towels to sop up the last bit in the bottom of the machine.
Clean your dishwasher air gap.
In most cases, a drain connection with a dishwasher air gap is the least likely to have problems, but whether yours has one depends on local building codes. Some communities require air gaps, but others require only a high loop under the sink cabinet in the hose. If your dishwasher has an air gap, it will typically be located next to your kitchen faucet (in the photo at right, the air gap is to the left of the spray nozzle).
Occasionally, an air gap can become clogged with debris, which can prevent the dishwasher from draining correctly and leave standing water in the dishwasher. To investigate, twist the air gap counterclockwise to remove it, and check the inside for gunk. Clean the air gap with water and a stiff brush, replace it, and run the dishwasher cycle again.
Clear up detergent mishaps.
Dishwashers are designed for use with automatic dishwasher detergents that clean without producing suds. In the course of a hectic day, it’s easy to accidentally squirt regular dishwashing liquid into the unit, which can easily create enough suds to prevent proper draining. The same problem can occur if you run out of automatic dishwasher detergent and substitute laundry detergent in a pinch. Guilty as charged? Simply bail out the tub as described above and run the cycle again, this time using the correct dishwasher detergent.
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De-gunk the drain basket.
The drain basket is often the source of a smelly clogged dishwasher. It’s found at the base of your dishwasher, usually below the bottom rack. Its cover often resembles an upside-down basket, which either snaps off or is held in place by one or two screws. (If the bottom of your machine doesn’t look like this consult your owner’s manual, which you can often download from the manufacturer’s website.)
Remove the cover, and check for food buildup in the basket beneath. Use your hand or a spoon to remove any debris, replace the cover, and run the dishwashing cycle again.
Note: If you find a lot of food debris in the drain basket, prevent future clogs by pre-rinsing your dishes. Most dishwashers manufactured today feature macerators that grind bits of soft wet food, but they don’t have the power of a garbage disposal. Even if your dishwasher’s manual says you needn’t pre-rinse the dishes, do so anyway to avoid repeatedly cleaning the drain basket.
Check the dishwasher drain hose for kinks.
A dishwasher drain hose—the lightweight, ribbed plastic hose that connects from the dishwasher’s drain pump to the garbage disposal (or to an air cap)—can prevent water from draining if it is kinked. If something large or heavy was shoved under the sink it might have hampered the dishwasher hose, so explore the area and locate the hose. If it is kinked, try straightening it out manually.
Unfortunately, once a drain hose kinks, it tends to happen again in the same spot. If this continues to happen, replace the drain hose. (It’s a simple enough DIY task—keep reading for details.)
Examine the drain hose for clogs.
If the hose isn’t kinked, it could still be clogged with food sludge or debris. To check for a clog, you’ll need to remove the lower front panel of the dishwasher and locate the spot where the ribbed hose attaches to the drain pump.
First, unplug the dishwasher: While you shouldn’t come in contact with any wiring, the general rule of thumb when working on appliances is to unplug them first. Place old towels under the unit and remove the lower front panel. Many panels snap off but, depending on your model, you may have to remove a screw or two. Disconnect the hose from the pump (if you’re unsure where it is or how to disconnect it, consult your owner’s manual).
To check the hose for clogs, simply blow through it. If air won’t pass through, you’ve got a clog. If the clog is located at either end of the hose, you can try to carefully remove it with a screwdriver or other thin implement, like a straightened out wire coat hanger.
If the clog is not located near the end connected to the pump, remove the hose where it connects to the garbage disposal or air cap to check for a clog on that end. If the clog is lodged deeper, you’ll probably have to replace the entire hose. Don’t try to clear the clog with a plumber’s snake. Dishwasher hoses aren’t designed to withstand the tool’s cutting motion and can be easily punctured.
Replace the drain hose.
For recurring kinks or a clog that you can’t remove, you’ll have to replace the entire hose. Call a plumber if you’re not comfortable trying this yourself. A pro could easily charge a minimum of $150 for a house call, so you’d save a bundle making the repair yourself. First, you have to unplug the dishwasher and slide it out from under the countertop.
Next, disconnect the old hose from both the pump and the garbage disposal (or the air gap), and attach the new one in the same manner. Consult your owner’s manual first to ensure that you purchase the correct replacement hose, and for any specific instructions on how it attaches to your appliance.
RELATED: 5 Reasons Your Dishwasher Is Leaking (and How to Fix It)
Call the plumber.
When we’re faced with a dishwasher not draining, one of the above techniques will usually solve the problem. If you have tried all these tips to no avail, the problem could lie in a faulty dishwasher pump, or in the dishwasher’s timer or motherboard. Replacing these specialty parts should only be done by a licensed plumber, so if you’re in that situation, call a plumber.
Final Thoughts
Most of the time, when you find a dishwasher not draining, the remedy is simple and inexpensive. It’s likely the result of a full garbage disposal that won’t allow the drain water to enter from the machine, so it backs up in the bottom of the dishwasher. Barring that, the problem is probably a kink in the drain hose, or a clog in the hose, the drain, or the air gap. When determining how to drain the dishwasher, the homeowner rarely needs to call a plumber if they follow the above steps.
Depending on the brand of dishwasher, you’ll find that most machines don’t have macerators (grinding disposals). For this reason, putting dishes in the dishwasher that still have chunks of food is a sure recipe for a clogged drain. Rinse your plates before washing them!
FAQs
Since it’s one of the handiest appliances in the home, the dishwasher is easily taken for granted—until it stops working. If dirty water is standing in the bottom of the machine after the cycle completes, the dishes will also be dingy, and the machine might smell bad. When the dishwasher won’t drain, a few questions are in order.
If the dishwasher won’t start, make sure the breaker that serves the electrical circuit hasn’t flipped off. Then, check to ensure the machine’s plug hasn’t become dislodged from the electrical outlet. Other things to check are whether a child safety lock has been activated and whether something is keeping the machine’s door from closing tightly.
Q: How do you clean a dishwasher drain hose without removing it?
You might be able to clean a dishwasher drain hose by pouring 1 cup of baking soda and 1 cup of white vinegar in the machine’s drain and then letting it sit for up to 15 minutes before flushing with hot water and then running a rinse cycle. This usually only works for clogs in the hose near the drain.
Q: How do I get rid of standing water in the dishwasher?
Try running the disposal and rerunning the dishwasher cycle. If that doesn’t remove the water, bail it out manually and proceed with the troubleshooting sequence.
Q: Will Drano ruin a dishwasher?
It certainly could. Drano is caustic and can eat through a plastic drain hose and damage the machine’s motor.
Q: Can you put baking soda and vinegar in dishwashers?
Yes. Mix equal parts of baking soda and white vinegar and put the solution in the drain for a few minutes before running a cycle. When used regularly—every month or so—this solution can help keep clogs from forming.