Why Is My Dishwasher Not Draining?

Standing water at the bottom of your dishwasher at the end of a cycle is a clear sign something is blocking the drain path. Most dishwasher draining problems are DIY-fixable. Here's how to diagnose and address the most common causes.

Step 1: Check for Obvious Blockages

Before assuming a mechanical failure, look for the obvious. Remove the lower rack and inspect the bottom of the tub. Food debris, broken glass, a small utensil, or even a label that peeled off a jar can block the drain opening. Remove any visible debris by hand.

Step 2: Clean the Filter and Drain Area

The dishwasher filter sits directly above the drain pump and is the first line of defense against blockages. A severely clogged filter restricts water flow to the drain pump and causes standing water. Remove and clean the filter as described in the cleaning article --- it's the most common cause of drain issues.

After removing the filter, inspect the drain opening beneath it. Use a flashlight to check for debris. Some dishwashers have a separate coarse filter screen that also needs cleaning.

Step 3: Inspect the Drain Hose

The drain hose carries water from the pump to your kitchen drain or garbage disposal. Common drain hose problems:

• Kink or crimp in the hose (common when the dishwasher has been pushed back against a cabinet)
• Clog inside the hose from accumulated grease and food debris
• Improper hose height --- the hose should loop up high under the counter (a 'high loop') before connecting to the drain to prevent backflow

Pull the dishwasher out slightly and trace the drain hose. Straighten any kinks. If you suspect an internal clog, disconnect the hose and flush it with water.

Step 4: Check the Garbage Disposal Connection

If your dishwasher drains into a garbage disposal, a common and easily overlooked problem is a blocked disposal inlet. When a new disposal is installed, there's a knockout plug inside the dishwasher inlet that must be removed. If it wasn't removed during installation, the dishwasher can't drain at all.

Also: run the garbage disposal before starting the dishwasher. If the disposal has standing water or food buildup, it can back up into the dishwasher.

Step 5: Test the Drain Pump

If all of the above checks out and the dishwasher still won't drain, the drain pump itself may have failed. Signs include: the dishwasher makes a humming noise but water doesn't move, or there's no sound from the pump at all during the drain cycle.

Drain pump testing requires accessing the pump through the filter area or the underside of the unit. A technician can test pump continuity and motor function quickly. Drain pump replacement is one of the more common dishwasher repairs and typically costs $150--$300 with labor.

Step 6: Check the Air Gap (If Installed)

Some kitchens have an air gap --- a small chrome fitting on the countertop or sink --- that prevents drain water from backing up into the dishwasher. When the air gap gets clogged with debris, it restricts drainage. Unscrew the top cap and clean out any buildup inside.