Dishwasher Not Cleaning Dishes? 8 Fixes Before You Call a Technician

1. Check how it is loaded

Overloading or blocking the spray arms is the most common cause. Large platters, cutting boards and tall pans can block the spray arm's rotation, and plates that nest together stop water from reaching their surfaces. Face dirty surfaces toward the centre, keep bowls tilted, and make sure the arms can spin freely by hand before starting a cycle.

Also avoid rinsing dishes to the point of spotlessness. Modern detergents contain enzymes that need food residue to work. Scrape off large pieces, but skip the pre-wash.

2. Clean the spray arms

Over time, minerals and food particles clog the small holes in the spray arms. Remove each arm according to your manual, rinse it under hot water, and use a toothpick to clear the holes. Check that the arm spins smoothly when reinstalled.

3. Clean the filter and sump

Most dishwashers have a filter at the bottom of the tub that catches food particles. When it clogs, dirty water is recirculated onto your dishes and drainage slows. Twist out the filter, rinse it, and scrub gently with a soft brush. Check the area below for broken glass, bones or labels, which can block the pump.

4. Check the water temperature

Dishwashers need hot water, typically around 50°C (120°F), to dissolve detergent and cut grease. Run the kitchen tap until it is hot before starting a cycle, so that the dishwasher fills with hot water from the start. If the water entering the dishwasher is cold, the detergent may not dissolve properly, leaving a gritty residue.

5. Use the right detergent and rinse aid

Detergent that is stale, damp or the wrong type can leave dishes cloudy. Store detergent in a dry place and make sure the dispenser door closes and opens properly. If you have hard water, as many Ottawa-area homes do, a rinse aid helps water sheet off glassware and reduces spotting. An occasional cleaning cycle with a dishwasher cleaner can also dissolve mineral deposits.

6. Check the water inlet

If the dishwasher is not filling with enough water, dishes will not get clean. Make sure the supply valve under the sink is fully open, and listen for the fill valve. A clogged inlet screen or a failing fill valve can limit water, leaving the bottom of the tub with only a thin film. Reduced water is a sign to book a service call.

7. Check drainage

Standing water at the bottom of the tub at the end of a cycle means that dirty water is not leaving the machine. A blocked drain hose, a clogged garbage disposal connection, or a failed drain pump are the usual causes. Check the drain hose for kinks, and if you have a disposal, make sure the knockout plug was removed when the dishwasher was installed.

8. Look at the wash pump and heating element

If the arms spin weakly even though they are clean, the wash pump may be failing, producing low pressure. If dishes are consistently not drying, the heating element may have failed. Both are parts that need to be tested and replaced by a technician.

When to call a professional

• Dishes are still dirty after cleaning the arms and filter.
• The dishwasher is not filling or draining properly.
• The spray arms barely spin or you hear a grinding noise.
• Dishes do not dry, or the water never seems to heat.
• The cycle stops partway through or shows error codes.

If you have worked through the list and the problem remains, book a diagnostic. We will find the failed component, explain the repair, and let you know whether it is worth fixing on your machine.