When the sink gurgles while the dishwasher drains, it is usually due to a phenomenon called "airlock" or "air gap." This occurs when there is a restriction in the drainage system, causing air to get trapped and resulting in the gurgling sound. Here's a brief explanation of why this happens:
Drainage system design: In a typical setup, both the sink and the dishwasher are connected to the same drainage system. The dishwasher's drain hose is usually connected to a port on the sink's drain pipe or garbage disposal unit.
Air gap: To prevent contaminated water from the sink or garbage disposal flowing back into the dishwasher, there is an air gap or an air break in the drain line. The air gap is a small vertical pipe or device that creates a physical separation between the dishwasher and the sink's drain system.
Water flow and airlock: When the dishwasher drains, it creates a flow of water through its drain hose. This flow of water can displace the air in the drainage system. However, if there is a restriction in the drain line or the air gap, the air may not escape freely.
Gurgling sound: As the dishwasher drains and water flows through the drain hose, the trapped air tries to escape. The air passing through the restricted area can cause vibrations, resulting in the gurgling sound you hear in the sink.
To address the gurgling issue, you can try the following steps:
Check the drain hose: Ensure that the dishwasher's drain hose is not kinked, pinched, or obstructed in any way. Straighten out any bends or obstructions to allow proper water flow.
Clean the air gap: If your sink has an air gap device, it might be clogged with debris. Disconnect the air gap cap or cover and clean it thoroughly. Remove any buildup that may be obstructing the airflow.
Clear the drain: Sometimes, the drain pipe or the garbage disposal unit itself may be clogged, causing the airlock. Use a plunger or a drain snake to clear any blockages in the sink's drain.
If these steps do not resolve the issue, it might be worth consulting a plumber or a professional appliance repair technician to diagnose and fix the problem.