Why Is There Standing Water at the Bottom of My Dishwasher?

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One of the more common things that alarm homeowners is when they notice standing water in the dishwasher days after it was last used. Why is there still water near the sump? Why is there still water in the bottom of my dishwasher? Shouldn’t it have all drained away? Well, not necessarily. The amount of water left in the tub after use will help determine if your dishwasher, or certain dishwasher parts, have a draining problem.

Some standing water in the dishwasher is normal

When we think about the various cycles a dishwasher will go through to clean our dishware, glassware, and utensils, we will often identify the “fill cycle” as the start of the dishwashing process. We’ve finished arranging the plates and bowls on the lower dishrack, the glasses and mugs on the upper dishwasher rack, and the utensils in the utensil basket. We’ve added the detergent and rinse aid, then closed the dishwasher door securely, selected the desired wash cycle, and pressed the start button. This sends voltage to the water inlet valve solenoid which opens the valve and allows the proper amount of water into the tub, right? Yes… eventually.

How a Dishwasher’s Fill Cycle Works

With most dishwashers, the first “fill cycle” actually begins with draining some water from the appliance. It’s only after this short drain cycle that the inlet valve solenoid will open and allow approximately two gallons of fresh water to fill the tub, a process that usually takes 90 seconds to two minutes.

Why is this old water being drained out prior to the fill cycle and not during the final drain cycle the last time the appliance was used? The dishwasher is designed to retain some water in the sump housing to help prevent the housing seals from drying out and cracking when the appliance is not in use.

How the dishwasher drains the tub

After the completion of each wash cycle, the control sends voltage to the dishwasher drain pump that uses an impeller to force the water through a drain hose to a garbage disposer or sink drain pipe. Some models without a separate drain pump will use a drain valve solenoid to open and close a flap to drain water through the drain hose or retain the water in the sump.

Water Pooling In the Dishwasher

While some water should be expected to remain near the sump housing after the draining and drying cycles have been completed, if you’re consistently seeing water pooling across the bottom of the tub area, or water is actually leaking onto the kitchen floor when you open the dishwasher door, the appliance has an actual draining problem. Your first troubleshooting step is to check to see that the drain hose is properly elevated. To ensure proper draining and prevent the water from flowing back into the tub, the drain hose must have a supported loop that goes above the drain hose’s connection point to the kitchen sink’s drain or the port on the garbage disposer the drain hose is attached to.

Top 5 Reasons Why The Dishwasher May Not Be Draining Properly and Leaving Standing Water

Have you confirmed the dishwasher’s drain hose is properly looped and elevated above its connection point? Then we can move on to the next five most likely reasons for why the dishwasher is not draining:

  1. Defective drain pump – Pump motors can fail both electrically and mechanically. You can use a multimeter to help determine if the pump has failed electrically by testing for electrical continuity, a continuous electrical path present in the motor. If the motor tests “negative” for continuity, the pump will need to be replaced. Be aware that some dishwasher models only have one motor to both circulate and drain the water.
  2. Clogged garbage disposer – If the dishwasher’s drain hose has been connected to a newly-installed garbage disposer, you should check to see if the knock-out plug has been inadvertently left in the disposer’s drain tube. The knock-out plug should literally be “knocked-out” (you can insert a flat-head screwdriver into the drain tube and strike the end of the tool with a hammer to detach the plug) to allow the dishwasher water to drain through the disposer. If the plug has been properly removed, it’s possible that the disposer is clogged with food debris, leaving standing water in the dishwasher. Try cleaning out the disposer’s drain tube to remove any obstruction.
  3. Obstructed drain hose – The drain hose itself can become obstructed as well. Since obstructions most commonly occur at either end, you should remove the drain hose from both the disposer/kitchen sink drain pipe and the dishwasher’s drain pump to inspect it for clogs or kinks in the hose to prevent water standing in the bottom of the dishwasher.
  4. Faulty drain solenoid valve – As noted earlier, some dishwasher models have a drain solenoid valve that opens to allow the water to drain. If the solenoid fails, the valve will not open. As with the pump motor, you can use a multimeter to test the drain solenoid for electrical continuity to help determine if the valve has failed electrically or not.
  5. Malfunctioning check valve or ball – The dishwasher uses a check valve to prevent water from returning to the tub once it’s been pumped out. If the check valve gets stuck in the closed position, the water won’t drain properly. You can try cleaning the valve, but if the problem continues, you should replace the valve with a new one. On some models, the check valve uses a check ball to prevent water from backing up into the tub. The water won’t drain if the ball gets stuck. If the check ball continues to get stuck in the valve, the ball should be replaced.

Repair Clinic Can Help You Fix Your Dishwasher’s Standing Water & Draining Problem

So, you’ve determined you need to replace the dishwasher’s drain pump to fix the draining problem. What’s the next step? Visit RepairClinic.com to identify the specific drain pump that works with your dishwasher. Just type the full model number of your dishwasher into the Repair Clinic website search bar to see a full list of compatible parts. For example, Whirlpool parts are going to be compatible with a Whirlpool appliance. You can then use the “Part Category” filter (“Pump”) along with the “Part Title” filter (“Drain Pump”) to narrow that list down to identify the specific pump that fits your model. Repair Clinic carries genuine manufacturer drain pump motors to help a dishwasher that has water in the bottom, along with drain solenoid valves, check valves, and drain hoses from all the top names in the industry, including Bosch, KitchenAid, Kenmore, Maytag, Samsung, GE, Frigidaire, LG, and Whirlpool, but you need to make sure you’re purchasing the exact part that works with your particular dishwasher for the repair to be successful.

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