How to Clean the Inside of a Dishwasher: A Complete Maintenance Guide

A grimy dishwasher doesn’t just look bad, it performs worse. Food debris, hard-water deposits, and soap residue accumulate inside the machine, leading to spotty dishes, lingering odors, and reduced cleaning power. The good news? Regular dishwasher cleaning is a straightforward maintenance task that takes less than an hour and requires no special plumbing skills. Most homeowners can do this themselves with basic supplies already sitting under the kitchen sink.

Why Regular Dishwasher Cleaning Matters

Your dishwasher works hard, cycling through hot water, detergent, and pressure to clean dishes. Over time, that same environment becomes a breeding ground for buildup. Hard water leaves mineral deposits on the heating element and interior walls. Food particles wedge into the spray arm holes, blocking water from reaching dishes in certain spots. Mold and mildew thrive in the rubber door gasket if moisture lingers between cycles.

A dirty dishwasher forces the machine to work harder, which means higher energy use and shorter appliance lifespan. Buildup can also transfer odors to clean dishes, making them smell stale even when they’re technically sanitary. According to home maintenance checklists, cleaning your dishwasher every one to three months prevents these problems and keeps dishes spotless. The investment in 30 minutes of preventive care saves hundreds in repairs or premature replacement.

Gather Your Supplies and Prepare the Machine

Before you open the dishwasher door, assemble everything you’ll need. Keep supplies close so you’re not hunting for tools mid-project.

Materials and supplies:

• White vinegar (distilled, if possible)

• Baking soda

• Dish soap or dishwasher cleaner (commercial options like Affresh or Lemi Shine work, but white vinegar is budget-friendly)

• Soft brushes or old toothbrushes

• Microfiber cloths or soft rags

• Warm water

• Rubber gloves (optional, but recommended)

Tools:

• Flashlight (to inspect hidden areas)

• Small wire brush or interdental brush (for spray arm holes)

• Flathead screwdriver (sometimes needed to remove spray arms, depending on your model)

Preparation steps:

1. Empty the dishwasher completely, including the silverware basket and racks.
2. Wipe out loose debris using a dry cloth or paper towel.
3. Run a quick hot-water cycle with the machine empty to loosen stuck-on food.

This prep work takes five minutes but makes the actual cleaning much more effective.

Clean the Spray Arms and Filter

Removing and Inspecting Spray Arms

Spray arms are the rotating components that distribute water during the wash cycle. Over time, food debris clogs the small holes, reducing water pressure and leaving dishes half-cleaned. Most spray arms lift out or unscrew, check your dishwasher manual to be sure, as designs vary.

1. Locate the spray arms (typically at the bottom and sometimes underneath the upper rack).
2. Gently lift or rotate the arm to release it: don’t force it if it doesn’t budge.
3. Hold the arm up to a light and look through the spray holes. You should see light coming through: if holes are blocked or darkened, cleaning is overdue.
4. Use a small wire brush, interdental brush, or straightened paperclip to clear each hole. Work gently, you’re removing mineral deposits or food, not enlarging the holes.
5. Rinse the arm under warm running water and set it aside.

Cleaning and Unclogging the Filter

The filter traps large food particles, preventing them from re-circulating onto dishes. A clogged filter forces water to work harder and can trigger error codes on newer machines.

1. Locate the filter (usually at the bottom, beneath the spray arm).
2. If it’s a two-part design, remove the outer cage first, then the inner fine filter.
3. Rinse debris into the sink under running water. A soft brush works well for stubborn spots.
4. For hard-water buildup or stubborn stains, soak the filter in a mix of equal parts white vinegar and warm water for 15–30 minutes, then scrub lightly and rinse.
5. Reinstall the filter and spray arms, making sure they’re fully seated and spinning freely.

Don’t use harsh scouring pads on filters, they’re designed to trap particles, and aggressive scrubbing can damage the mesh.

Deep Clean the Interior and Seals

Now focus on the walls, heating element, and seals where grime hides.

Walls and interior surfaces:

1. Mix two tablespoons of baking soda with a small amount of warm water to form a paste.
2. Using a soft brush or microfiber cloth, scrub the interior walls, paying attention to corners and crevices where mold grows.
3. Don’t forget the door interior, spray buildup accumulates there too.
4. Rinse thoroughly with a damp cloth, squeezing water into all areas.

Rubber door gasket and seals:

The gasket is a common mold hotspot because it stays damp. Mold here smells bad and can transfer to dishes.

1. Wipe the gasket with a cloth dampened in equal parts white vinegar and warm water.
2. Use an old toothbrush to scrub inside the groove, where mold hides.
3. Dry the gasket completely with a clean cloth: moisture is the enemy.

If you notice cracks or deterioration in the gasket, it’s time to replace it, a $30–60 part that prevents leaks and mold growth.

Heating element and drain:

Never scrub the heating element directly (you’ll damage it), but ensure the drain at the bottom is clear.

1. Remove any visible food debris or buildup from the drain opening with a paper towel or soft cloth.
2. If the drain smells foul, pour a cup of white vinegar directly down it and let it sit for 15 minutes, then run a short hot-water cycle.

Run a Vinegar or Cleaning Cycle

The final step is a chemical clean that dissolves remaining mineral deposits and kills odor-causing bacteria.

With white vinegar:

1. Place a cup of white vinegar in a dishwasher-safe bowl on the top rack.
2. Run a normal hot-water cycle with the machine empty.
3. When the cycle finishes, sprinkle baking soda on the bottom of the tub and run a short hot-water cycle again to remove vinegar odor and boost cleaning power.

With commercial dishwasher cleaner:

Brands like Affresh or Cascade Complete are formulated specifically for this job. Follow the package directions (typically, place the packet or tablet in the dispenser and run a hot cycle). Comprehensive home improvement how-tos often recommend these products for stubborn hard-water stains.

Final notes:

Never use bleach, it can damage stainless steel interiors and rubber seals. If your machine smells funky even after cleaning, run another vinegar cycle. Persistent odors sometimes indicate a blockage deeper in the drain line, which may require professional service.

After cleaning, leave the door open for 15–20 minutes to air-dry completely. This prevents mold from returning immediately.