The gurgling sound you hear when the dishwasher drains is due to a phenomenon called "airlock" or "air gap." To understand this, it's essential to know how a dishwasher drains water.
Most dishwashers use a pump to remove water from the machine. As the dishwasher drains, it pushes the used water through a hose or pipe connected to the sink's plumbing system or garbage disposal unit. The water is then sent into the drainpipe, which leads to the sewer system or septic tank.
When the dishwasher rapidly drains a significant amount of water, it creates a vacuum effect in the drainpipe. As water rushes out of the dishwasher, it can momentarily create a low-pressure zone in the pipe. This low-pressure area can cause air to be drawn into the pipe through the sink's drain, resulting in the gurgling sound you hear.
Additionally, the gurgling may also occur due to improper or insufficient venting of the plumbing system. Plumbing systems typically have vents that allow air to enter the system and equalize pressure, preventing issues like airlock and gurgling. If the vents are clogged or not properly installed, it can lead to airlock problems and noisy drainage.
To address this issue, you can try the following:
Check the dishwasher's drain hose: Make sure it's correctly installed and not kinked or blocked.
Check the sink's drain: Ensure it's not clogged, as a blockage can exacerbate the gurgling sound.
Check the plumbing vent system: If you suspect an issue with the venting, you may want to call a plumber to inspect and clean the vents.
Consider using an anti-siphon valve or air gap device: These devices can be installed to prevent airlock and gurgling by providing a physical gap between the dishwasher's drain line and the sink's plumbing.
If the problem persists and you're unsure how to address it, it's best to consult a professional plumber to ensure proper drainage and ventilation in your plumbing system.