Why Your Dishwasher Isn't Cleaning & How to Fix It

Why Your Dishwasher Isn’t Cleaning Properly (And What to Do About It)

You run a full cycle, open the door expecting clean dishes—and find last night’s pasta still stuck to the bowl. Frustrating doesn’t quite cover it. A dishwasher that fails to do its one job can throw off your entire kitchen routine, especially during busy weeknights or after hosting guests.

The good news? Most dishwasher problems have straightforward causes. Many can be fixed with a bit of DIY dishwasher troubleshooting. Others point to a deeper mechanical issue that calls for a professional. This guide walks you through the most common dishwasher problems, what causes them, and when it makes sense to call in an expert.

Dishes Coming Out Dirty or Cloudy

This is the most common complaint—and it usually comes down to one of three things: a clogged filter, blocked spray arms, or incorrect loading.

Check and Clean the Filter

Most modern dishwashers have a removable filter at the base of the tub. Over time, food debris builds up here and restricts water flow, leaving dishes grimy even after a full wash.

Remove the filter by twisting it counterclockwise
Rinse it under warm running water
Use a soft brush to remove stubborn buildup
Reinstall and run a test cycle

Cleaning the filter once a month is a simple habit that makes a measurable difference.

Inspect the Spray Arms

The spray arms distribute water throughout the dishwasher during a cycle. If their small holes become blocked with mineral deposits or food particles, water pressure drops and cleaning performance suffers.

Remove the spray arms (usually just a matter of unscrewing them)
Hold them under running water and use a toothpick to clear any clogged holes
Reinstall them and confirm they spin freely

Load Dishes Correctly

Overcrowding is a surprisingly common culprit. Dishes stacked too close together block water from reaching all surfaces. Face dishes toward the spray arms, avoid nesting bowls, and never block the detergent dispenser.

The Dishwasher Isn’t Draining Properly

Standing water at the bottom of your dishwasher after a cycle is a red flag. It suggests a drainage problem that, if left unaddressed, can lead to unpleasant odors and potential water damage.

Common Causes of Poor Drainage

Clogged drain hose: Food debris or kinks in the drain hose can prevent water from exiting. Check that the hose runs without sharp bends and clear any visible blockages.
Blocked drain basket: Located at the base of the machine, the drain basket can collect debris. Remove and clean it regularly.
Faulty drain pump: If the hose and basket are clear but water still pools, the drain pump may have failed. This is a repair best left to a technician.

Dishwasher Is Leaking

A leaking dishwasher can cause significant water damage to your flooring and cabinetry. Catching the source early is critical.

Where Leaks Typically Start

Door gasket: The rubber seal around the door can crack or warp over time, allowing water to escape. Inspect it for visible damage and replace it if worn.
Water inlet valve: A faulty inlet valve can cause water to leak at the back of the machine. This component controls water flow into the dishwasher and may need replacement if damaged.
Door latch: A loose or misaligned door latch can prevent the door from sealing properly during a cycle.

If you can’t identify the source of the leak, or if water is pooling underneath the unit, stop using the dishwasher and contact an appliance repair Calgary technician to avoid further damage.

Dishwasher Making Unusual Noises

A dishwasher in good working order produces a consistent hum. Grinding, banging, or rattling sounds are worth investigating.

What Different Noises Mean

Grinding: Often caused by broken glass or debris caught in the pump or spray arms. Check the base of the tub and remove any foreign objects.
Banging or thumping: Loose items in the racks—like lightweight plastic lids—can flip around during a cycle and hit the spray arms. Secure items before running a wash.
Rattling: Dishes that aren’t properly secured may knock against each other. Reload and try again.
Humming that gets louder over time: This can indicate a worn wash pump motor, which will likely need professional attention.

Dishwasher Not Drying Dishes

Opening the dishwasher to find wet dishes is a common annoyance, but it’s usually easy to address.

How to Improve Drying Performance

Use rinse aid: Rinse aid helps water sheet off dishes rather than forming droplets that linger. Check the rinse aid reservoir and refill it if empty.
Select the heated dry setting: If your dishwasher has a heated dry option, make sure it’s enabled. Some models default to air dry, which is less effective.
Unload bottom rack last: Water collects on the base of cups and bowls sitting in the top rack and drips onto dishes below when you open the door. Unloading from the bottom up prevents this.
Avoid plastic-heavy loads: Plastic doesn’t retain heat well, so it tends to stay wet regardless of the drying method. Pat these items dry by hand if needed.

If the heating element itself has failed, the dishwasher won’t dry dishes at all—a technician will need to test and replace the component.

Dishwasher Has an Unpleasant Smell

A musty or foul odor coming from your dishwasher usually means food residue or mold has accumulated somewhere inside the machine.

How to Eliminate Dishwasher Odors

Clean the filter and drain basket: As mentioned, these areas trap food debris and are a prime source of odors.
Wipe down the door seal: Mold and mildew tend to accumulate in the folds of the rubber gasket. Use a damp cloth and a mild cleaning solution to scrub it clean.
Run a cleaning cycle: Place a dishwasher-safe bowl filled with white vinegar on the top rack and run a hot cycle. Follow up with a sprinkle of baking soda on the base and run a short hot cycle.
Leave the door ajar after cycles: Allowing air to circulate inside the tub after each wash prevents moisture buildup and discourages mold growth.

If the smell persists despite cleaning, there may be a blockage deeper in the drainage system that requires professional inspection.

When to Stop Troubleshooting and Call a Professional

DIY fixes go a long way with minor dishwasher issues. But certain problems—persistent leaks, electrical faults, pump failures, or error codes you can’t clear—call for a licensed technician. Attempting complex repairs without the right tools or training can cause further damage and may void your manufacturer’s warranty.

For Calgary homeowners dealing with a stubborn dishwasher problem, professional help is worth it. Skilled technicians can diagnose issues accurately, source original OEM parts, and complete most repairs in a single visit. If you’ve worked through the troubleshooting steps above and your dishwasher still isn’t performing as it should, click here to book a same-day Calgary dishwasher repair service with Maple Leaf Appliance Repair—a TSSA-licensed team serving Calgary and surrounding areas with over 2,000 positive reviews.

A well-functioning dishwasher is one of those appliances you don’t appreciate until it stops working. A little regular maintenance—cleaning the filter, checking the spray arms, using rinse aid—goes a long way toward preventing most common issues. And when something more serious does come up, knowing when to call a professional saves you time, money, and the headache of a bigger repair down the road.