Why is my dishwasher causing the sink to back up?

 

Why Your Dishwasher Is Causing the Sink to Back Up

  When your dishwasher causes the sink to back up, it usually means that there is a blockage or clog in the shared drain pipe that both the sink and dishwasher use for water disposal. The dishwasher sends its wastewater through a hose that connects to the same drain line as the sink. If this drain line is partially or completely blocked, the water cannot flow through easily and ends up flowing back into the sink.

 

How the Drainage System Works

  Most kitchens are set up so that appliances like the dishwasher, garbage disposal, and sink are connected to a single drain pipe. When the dishwasher finishes its cycle, water flows out through a drain hose into the sink’s drain line. This hose is supposed to have a “high loop” – a bend that helps prevent water from one appliance flowing backward into another. However, if the drain pipe somewhere along the line is clogged with food particles, grease, or soap residue, the water from the dishwasher finds an alternate, easier route and backs up into the sink.

 

Common Reasons for the Blockage

 

• Food Debris and Grease Buildup: Over time, bits of food and grease can accumulate in the drain line. Even a small amount can eventually build up and create a blockage.
• Soap and Detergent Residue: The dishwasher uses detergents that can sometimes mix with food particles and grease to form a sticky substance that sticks to the pipes.
• Lack of Proper Drain Hose Installation: If the drain hose does not have a proper “high loop” or air gap, water may more easily flow the wrong way if the drain is even slightly clogged.
• Clog in the Garbage Disposal: If your kitchen sink’s drain is connected to a garbage disposal unit, any blockage there can also affect the flow of water coming from the dishwasher.

 

Step-by-Step Troubleshooting Guide

 

• Inspect and Clean the Sink Drain: Begin by checking the sink drain for any visible obstructions. If you notice debris or buildup, try removing it manually or using a drain tool.
• Check the Dishwasher Drain Hose: Look under the sink to find the hose where the dishwasher drains. Ensure that it is properly connected, has a high loop, and is not kinked or damaged.
• Examine the Garbage Disposal: If your sink has a garbage disposal, check if it is working correctly. Sometimes, clogs in the disposal unit can cause water to back up into the sink.
• Use a Drain Cleaner or Snake: Consider using a non-corrosive drain cleaner or a plumbing snake. This tool can help break up or remove any clogs within the drain pipe.

 

Additional Considerations and Professional Help

  If you have tried cleaning the sink and checking the dishwasher’s hose without success, it might be time to seek professional assistance. A licensed plumber can inspect your entire drainage system and remove deep-seated blockages that are not accessible with standard tools. This ensures that your pipes run freely, and you won’t experience recurring back ups.

For residents or business owners in St. Louis and Nashville, trusted professionals like Hoffman Brothers offer full-service residential and commercial plumbing solutions. They can diagnose complex drainage issues and ensure your sink and dishwasher operate smoothly, saving both time and money as well as preventing future headaches.

 

Conclusion

  In summary, the backup of water in your sink when the dishwasher runs is typically caused by a clog in the shared drainage system. By understanding how your plumbing is set up and knowing what to look for, you can take steps to clean the drains and check the hose connections. If these steps do not resolve the issue, professional help from a qualified plumber is recommended to permanently fix the problem.