Why Your Dishwasher Isn't Cleaning Dishes (And How to Fix It)

Start Here: Clean the Filter

Most dishwashers made after 2010 have a manual filter at the bottom of the tub that traps food particles. Unlike older self-cleaning filters, these need to be cleaned by hand every 1–3 months. A clogged filter dramatically reduces cleaning performance. Remove it (it usually twists out), rinse it under running water, scrub it with a soft brush and dish soap, and reinstall. This alone fixes "dirty dishes" complaints in a large percentage of cases.

Check the Spray Arms

The spray arms spin and shoot water through small holes to clean your dishes. Those holes get clogged by hard water minerals and small food particles over time. Remove the spray arms (they typically unscrew or unclip), hold them over a sink, and clear any clogged holes with a toothpick or small wire. Run water through them to confirm flow is clear before reinstalling.

Water Temperature

Dishwashers need water at 120°F–140°F to properly dissolve detergent and cut through grease. If your water heater is set too low, detergent won't activate fully. Run the hot water tap at your kitchen sink for 30 seconds before starting a cycle — this purges cold water from the line and ensures the first fill is hot. If dishes are still coming out greasy, check your water heater setting.

Detergent Dispenser Issues

If the detergent dispenser door is blocked by a large dish or pot in the bottom rack, it can't open during the wash cycle and the detergent never enters the tub. Always load the bottom rack so the dispenser door has clear space to swing open. Also check that the dispenser latch isn't cracked or sticking — a broken dispenser door is a straightforward replacement.

Hard Water Buildup

Hard water leaves a white, chalky film on glasses and dishes. If you see this, run an empty dishwasher with a cup of white vinegar in the bottom rack and a dishwasher cleaning tablet. Repeating this monthly prevents buildup. A rinse aid dispenser also significantly reduces spotting — make sure it's filled and the dispenser setting is appropriate for your water hardness.

When the Problem Goes Deeper

If you've cleaned the filter, cleared the spray arms, and confirmed water temperature and the dishwasher still isn't cleaning, the issue is likely mechanical: a failing wash pump motor, a faulty water inlet valve, or a malfunctioning control board. These are not DIY repairs and require a technician. The typical repair cost for a wash pump motor is $150–$300, which is usually worth it on a dishwasher under 8 years old.