How to Fix a Commercial Dishwasher Drain Pump That Isn’t Draining

How to Fix a Commercial Dishwasher Drain Pump That Isn’t Draining

Commercial kitchens rely heavily on their dishwashers to maintain hygiene and efficiency. When a dishwasher’s drain pump malfunctions and the machine refuses to drain properly, it disrupts workflow and compromises cleanliness standards. Understanding how to diagnose and repair a commercial dishwasher drain pump issue is essential for kitchen managers, maintenance staff, and even business owners who want to minimize downtime and repair costs.

In this article, we’ll walk you through a comprehensive guide to troubleshooting and fixing a commercial dishwasher that isn’t draining, with practical steps, safety tips, and insights into common causes.

Why Is Proper Drainage Critical in Commercial Dishwashers?

Proper drainage in commercial dishwashers is essential for maintaining both operational efficiency and hygiene standards in busy kitchens. When water drains effectively, it prevents multiple issues that can otherwise disrupt daily workflows. Here’s why drainage matters so much:

1. Proper drainage removes dirty water and food particles after each wash cycle, preventing bacterial growth and foul odors inside the machine. This is crucial for meeting health code regulations.

2. Standing water inside the dishwasher can corrode internal components and cause leaks, resulting in costly repairs and potential damage to commercial kitchen flooring and cabinetry.

3. If wastewater isn’t expelled properly, dishes remain dirty or spotted with residue, undermining the effectiveness of the wash cycle and requiring re-washing.

4. Efficient drainage prevents strain on the dishwasher’s pump and motor. When water pools, these parts must work harder or risk overheating and failure.

5. Proper drainage minimizes breakdowns, keeping your commercial kitchen running smoothly without interruptions for repairs.

6. Health departments often inspect commercial dishwashers. Faulty drainage can lead to violations and penalties.

Guide to Fixing the Commercial Dishwasher Drain Pump

When your commercial dishwasher isn’t draining properly, the dishwasher drain pump is often the culprit. Fixing this issue involves a careful process of inspection, cleaning, testing, and possibly replacing the pump. Follow these steps to troubleshoot and repair the problem efficiently:

1. Safety First: Preparing to Work on Your Dishwasher

Water and electrical components are involved while working with commercial kitchen equipment, so safety precautions are paramount:

1. Unplug the dishwasher from its power source to avoid electric shock.

2. Turn off the dishwasher's water supply valve.

3. Use rubber gloves to protect your hands from sharp parts and dirty water.

4. When disconnecting hoses, get a bucket or towels ready to catch any remaining water.

5. Review the manufacturer’s manual for model-specific instructions.
   

2. Inspect and Clean the Drain and Filter Area

One of the most frequent reasons a commercial dishwasher fails to drain is a clogged filter or blocked drain opening. These components can easily become filled with food particles, grease, and debris over time, restricting water flow to the pump. Starting with a thorough inspection here can save you time and effort.

1. Open the dishwasher door and pull out the lower rack to access the bottom of the tub.

2. Locate and remove the filter assembly—typically found near the drain hole.

3. Rinse the filter thoroughly under warm running water to remove grease and food buildup.

4. Inspect the drain opening for any visible obstructions such as seeds, glass shards, or utensils.

5. Use a gentle brush or cloth to clean around the drain area.

6. Reinstall the filter securely, ensuring it's properly aligned.

7. Check if the water drains away adequately by running a quick drain cycle.

   
   

3. Check the Drain Hose

A blocked or damaged drain hose is a common reason why water doesn’t drain properly. The dishwasher is connected to the building's plumbing system via this hose and can become kinked, clogged, or loose over time. To inspect and clean it:

1. Find the drain hose by tracing it from the dishwasher to the wall or floor drain.

2. Check for visible damage, kinks, or sharp bends that may restrict water flow.

3. Detach the hose carefully from both ends to avoid spills.

4. Flush it out with water or use a flexible cleaning brush to dislodge any clogs.

5. Reconnect the hose tightly and run a cycle to test for proper drainage.
   

4. Access the Drain Pump

If cleaning the filters and drain hose doesn’t solve the drainage issue, it’s time to inspect the pump itself. Follow these steps:

1. Refer to the service manual for your specific dishwasher model to locate the drain pump — it’s typically positioned near the bottom of the unit.

2. Unplug the dishwasher or disconnect it from its power source to ensure safety.

3. Remove the lower access panel, usually found on the front or rear underside of the unit. It’s typically secured with a few screws.

4. Carefully disconnect the electrical connectors attached to the pump.

5. To catch any remaining water, keep a towel or pail close at hand as you disconnect the input and outlet hoses that lead to and from the pump.
   

5. Test the Drain Pump Motor

To ascertain whether the pump motor is operating properly, follow these steps using a multimeter:

1. Set your multimeter to the resistance (ohms/Ω) setting.

2. Disconnect the pump from the power supply and access the motor terminals.

3. Place the multimeter probes on the motor’s electrical terminals.

4. Compare the reading to the manufacturer’s recommended resistance range (typically found in the service manual).

5. Significantly high or low readings may indicate a faulty motor that needs replacing.

6. If you don't have a multimeter, listen while the drain cycle is going on — if you don’t hear the pump running, it may be burned out or jammed.
   

6. Clean the Pump and Impeller

The drain pump itself is functional in some cases, but the impeller—the small fan-like component inside—may be jammed or obstructed.

1. Disconnect the pump from its housing to access the impeller.

2. Remove any visible debris, gunk, or buildup around the impeller area.

3. Manually spin the impeller to ensure it moves freely without resistance.

4. Clean the pump housing with a cloth and mild detergent to remove any residual grime.

5. Inspect for cracks or damage on the impeller while cleaning.

6. Reassemble every part and ensure drainage by running a test cycle.
   

7. Change the Drain Pump if Necessary

The best course of action is to replace the impeller if it breaks or the pump motor is electrically damaged.

1. Purchase a genuine replacement part compatible with your dishwasher model.

2. Install the new pump by reversing the removal process.

3. Ensure all electrical and hose connections are secure.

4. Test the dishwasher to confirm proper drainage.
   

Preventative Maintenance Tips

To prevent future drain pump issues and extend the longevity of the commercial dishwasher, follow these simple maintenance tips:

1. Clean filters and screens regularly to avoid clogs from food particles and grease buildup.

2. Flush the drain hose occasionally using warm water and a mild detergent to remove residue and prevent blockages.

3. Scrape off large food scraps before loading dishes to minimize debris entering the system.

4. Schedule professional maintenance every 6 to 12 months to catch issues early and ensure peak performance.

5. Use only recommended detergents and avoid harsh chemicals that can corrode or damage internal components.

A commercial dishwasher that won’t drain can severely impact commercial kitchen operations. However, by understanding the role of the drain pump and following systematic troubleshooting steps, you can often resolve the issue without costly downtime. Remember to always prioritize safety, consult your equipment manual, and keep maintenance consistent to prevent future failures. By addressing clogs early, inspecting hoses, testing the pump motor, and replacing faulty parts when needed, your dishwasher will continue to operate efficiently—helping your kitchen maintain the high standards your business depends on.

Written by Allen Rode for PartsFe, your trusted source for a variety of high-quality commercial dishwasher parts, including dishwasher drain hoses and dishwasher impellers.