A clogged filter is one of the most common reasons a dishwasher stops getting dishes clean — when it is blocked, food particles that should be trapped and rinsed away get redistributed back onto your dishes instead. After the filter, clogged spray arm holes, improper loading, and water temperature or detergent issues are the next most common causes.
Clean the filter first
Most modern dishwashers have a removable filter near the bottom of the tub that traps food particles during the wash. Once it clogs, water cannot circulate the way it is designed to, and trapped debris ends up back on your dishes instead of being flushed away. See our dishwasher filter cleaning guide for the full removal and cleaning process — this single step resolves a large share of cleaning complaints on its own.
Check and clean the spray arms
- Remove the spray arms per your model’s manual
Most simply lift or unclip out without tools.
- Check each hole for blockages
Hard water deposits and food debris commonly clog the small spray holes over time.
- Clear blocked holes with a toothpick
Small enough to clear debris without enlarging or damaging the holes.
- Confirm the arms spin freely once reinstalled
A spray arm that catches on a tall dish or utensil during loading cannot rotate to cover the full tub.
Check how the dishwasher is loaded
| Loading issue | Why it prevents proper cleaning |
|---|---|
| Overcrowding the racks | Blocks water and detergent from reaching between dishes |
| Nesting bowls or plates together | Water cannot reach the surfaces facing each other |
| Tall items blocking the spray arm’s rotation | Prevents water from covering the full tub |
| Placing items directly over the detergent dispenser | Can physically block the dispenser from opening |
Water temperature matters more than expected
Dishwashers generally need water at least around 120°F to dissolve detergent and clean effectively. If your home’s water heater is set low, or the dishwasher is far from the water heater and the first few minutes of the cycle run on lukewarm water, cleaning performance suffers even with everything else working correctly. Running the kitchen hot tap briefly before starting the dishwasher can help ensure hot water reaches it faster.
Detergent and rinse aid issues
Using too much detergent creates excess suds that interfere with the wash rather than improving it, and can leave residue that looks like the dishes were not properly cleaned. An empty rinse aid dispenser is a separate, common cause of dishes coming out with spots or a filmy residue even when they are technically clean underneath — see our white film on glasses guide if that matches what you are seeing.
Hard water buildup
Mineral deposits from hard water can build up inside the dishwasher over time, reducing how freely the spray arms spin and even partially blocking water valves. Running an empty cycle with a dishwasher-safe descaling product periodically helps prevent this buildup from accumulating to the point where it affects cleaning performance.
When to call a professional
If the filter and spray arms are clean, loading is reasonable, water temperature is confirmed adequate, and the correct detergent and rinse aid are being used, but cleaning is still poor, a failed water inlet valve, wash pump, or heating element is the more likely remaining cause — each needs a technician to properly diagnose.
