You open your dishwasher after a full cycle and find glasses with water spots, plates with food residue, and silverware that still looks dirty. A dishwasher that does not clean properly wastes water, detergent, and your time — and it usually has a clear cause that you can diagnose and often fix yourself.
This guide covers every common reason your dishwasher is not cleaning dishes, provides step-by-step fixes, and tells you when to call a professional.
Quick Answer: If your dishwasher is not cleaning, the most common causes are clogged spray arms, a dirty filter, hard water deposits, using the wrong detergent, or a failed wash pump. Start by removing and cleaning the spray arms and filter, then run a cycle with a dishwasher cleaner. If dishes are still dirty, check the water temperature and detergent quality.
Why Your Dishwasher Is Not Cleaning: The Most Common Causes
1. Clogged Spray Arms
The spray arms are the rotating wands that distribute water throughout the dishwasher. Each arm has small nozzles that direct high-pressure water at your dishes. When food particles, mineral deposits, or debris block these nozzles, water cannot reach all areas of the dishwasher, resulting in dirty dishes.
Remove both the upper and lower spray arms by twisting them off or unscrewing the retaining nut. Hold each arm up to the light and look for blocked nozzles. Clear any clogs with a toothpick or a thin wire. Rinse the arms under strong running water. If the clogs are mineral deposits, soak the arms in white vinegar for 30 minutes before cleaning.
2. Dirty or Clogged Filter
Most modern dishwashers have a removable filter at the bottom of the tub that catches food particles before they reach the drain pump. When this filter becomes clogged, water cannot circulate properly and food residue redeposits on your dishes.
Remove the filter — it is usually a cylindrical mesh component at the bottom of the tub — and rinse it under hot water. Use a soft brush to scrub away stuck-on debris. If the filter is torn or deteriorated, replace it. Clean the filter every 4 to 6 weeks for best performance.
3. Hard Water Deposits
Toronto's water is moderately hard, which means it contains minerals — primarily calcium and magnesium — that leave deposits on dishwasher components and your dishes. Over time, these minerals build up inside the spray arms, on the heating element, and throughout the wash system, reducing cleaning effectiveness.
Hard water also causes cloudy glasses and white spots on dishes. To address hard water deposits, run an empty cycle with 2 cups of white vinegar poured into a bowl on the top rack. Follow with an empty cycle using a dishwasher cleaner like Afresh or Finish. For ongoing prevention, use a rinse aid and consider adding a dishwasher salt if your model supports it.
4. Low Water Temperature
Dishwashers need water at a minimum of 120 degrees Fahrenheit to dissolve detergent and dissolve food effectively. If your water heater is set too low, or if the dishwasher is far from the heater and the water cools in the pipes, the water inside the dishwasher may not be hot enough to clean properly.
Run the kitchen sink on hot for 30 seconds before starting the dishwasher — this ensures that hot water is at the dishwasher inlet when the cycle begins. You can also check the water temperature inside the dishwasher by placing a thermometer in a glass on the top rack during a cycle.
5. Wrong or Expired Detergent
Dishwasher detergent loses effectiveness over time, especially pods and tablets that are exposed to moisture. Old detergent may not dissolve completely, leaving residue on dishes and inside the dishwasher.
Use fresh detergent and store it in a cool, dry place. If you have been using the same box or bottle for more than a few months, replace it. In hard water areas like Toronto, enzyme-based detergents (not chlorine-based) are more effective at removing food residue.
6. Overloading or Improper Loading
A dishwasher that is packed too tightly cannot spray water onto all surfaces. Large items like pots and baking sheets can block spray paths, leaving dishes in their shadow dirty. Bowls placed face-down trap water and food instead of letting it drain.
Follow your dishwasher's loading guide. Place plates between the tines, face the soiled surfaces toward the center, angle bowls downward, and do not nest items. Make sure the spray arms can rotate freely by spinning them by hand before closing the door.
7. Failed Wash Pump
The wash pump circulates water through the spray arms during the wash cycle. If the pump motor fails or the impeller is damaged, water will not be pushed through the spray arms with enough force to clean dishes properly.
Signs of a failing pump include a hum or buzz during the wash cycle (instead of the normal sound of water spraying), dishes that are wet but not clean, and food residue concentrated in certain areas of the dishwasher where spray does not reach. Pump replacement requires accessing the bottom of the dishwasher and is usually handled by a professional.
8. Faulty Dispenser
The detergent dispenser releases detergent at the correct time in the cycle. If the dispenser door does not open, the detergent stays in the cup and your dishes go through the entire cycle without soap. If the door opens too early, the detergent washes away before the main wash cycle begins.
Run a cycle and check whether the dispenser door has opened at the end. If the dispenser cup still contains detergent or the door is stuck closed, the dispenser mechanism needs replacement.
Step-by-Step: How to Fix a Dishwasher That Is Not Cleaning
Step 1: Clean the Spray Arms
Remove both spray arms and hold them up to the light. Clear any blocked nozzles with a toothpick. Soak mineral-clogged arms in white vinegar for 30 minutes. Rinse thoroughly and reinstall.
Step 2: Clean the Filter
Remove the filter at the bottom of the tub. Rinse it under hot water and scrub with a soft brush. Replace it if it is torn or deteriorated.
Step 3: Run a Vinegar Cycle
Place 2 cups of white vinegar in a dishwasher-safe bowl on the top rack. Run the hottest cycle available with no other dishes. The vinegar dissolves mineral deposits and detergent residue throughout the wash system.
Step 4: Run a Dishwasher Cleaner Cycle
After the vinegar cycle, run a second empty cycle with a commercial dishwasher cleaner like Afresh or Finish. This removes any remaining residue and deodorizes the interior.
Step 5: Check Water Temperature
Before starting a cycle, run the kitchen sink on hot for 30 seconds to ensure hot water reaches the dishwasher. Check the temperature inside the dishwasher by placing a thermometer in a glass on the top rack during a cycle.
Step 6: Replace Old Detergent
Discard any detergent that is more than 3 months old or shows signs of clumping. Switch to a fresh enzyme-based detergent and add rinse aid to the dispenser.
Step 7: Improve Your Loading Technique
Make sure dishes face the spray arms. Do not nest bowls or stack plates too closely. Ensure the spray arms rotate freely before closing the door.
When to Call a Professional
If you have cleaned the spray arms, filter, and interior, replaced your detergent, confirmed water temperature, and your dishwasher is still not cleaning properly, the problem may be a mechanical component — a failing wash pump, a cracked spray arm that cannot build pressure, or a faulty dispenser that will not open.
Appliance Service Plus has been serving Toronto homeowners with reliable dishwasher repair for years. Their technicians carry commonly needed parts for Bosch, KitchenAid, Samsung, and other major brands. If you are in Toronto, Scarborough, North York, or the GTA, schedule a service call.
Frequently Asked Questions
Why are my glasses cloudy after the dishwasher?
Cloudy glasses are usually caused by hard water deposits or etching. Hard water leaves a white film that can be removed by soaking the glasses in white vinegar for 15 minutes. If the vinegar soak does not remove the cloudiness, the glass is etched — a permanent condition caused by detergent that is too strong or water that is too hot. Using rinse aid and a fresh detergent usually prevents both issues.
Can I use vinegar instead of dishwasher cleaner?
Yes, white vinegar is an effective and affordable dishwasher cleaner. Pour 2 cups into a bowl on the top rack and run the hottest cycle with no dishes. Vinegar dissolves mineral deposits and removes mild odours. For heavy buildup, follow with a commercial dishwasher cleaner.
How often should I clean my dishwasher filter?
Clean the filter every 4 to 6 weeks, or more frequently if you run the dishwasher daily or do not scrape plates before loading. A clogged filter is the single most common cause of poor dishwasher performance.
Why does my dishwasher leave food on dishes?
The most common causes are a clogged filter, blocked spray arm nozzles, overloading, or using old detergent. Start by cleaning the filter and spray arms, then adjust your loading technique and replace old detergent with fresh enzyme-based pods or liquid.
