A sink gurgling when the washing machine drains may be the result of a clogged or blocked drain. When the washing machine drains, the water flows through the same pipes as the sink and other plumbing fixtures in the house. If the drain is clogged or blocked, it can cause air to become trapped in the pipes, leading to a gurgling sound.

There are several potential causes of a clogged drain. One common cause is the accumulation of debris in the pipes, such as hair, soap scum, and food particles. This can create a blockage that prevents water from flowing freely through the pipes.

Another potential cause of a clogged drain is tree roots growing into the pipes. Tree roots can invade the pipes in search of moisture, creating a blockage that can lead to a gurgling sound.

A blocked drain can also be caused by a plumbing issue, such as a collapsed or broken pipe. In this case, the blockage may be located somewhere in the plumbing system rather than in the drain itself.

If a sink is gurgling when the washing machine drains, it is a good idea to check the drain for any visible blockages. If no blockages are found, it may be necessary to call a plumber to diagnose the issue and determine the necessary repairs.

Overall, a sink gurgling when the washing machine drains may be the result of a clogged or blocked drain. Identifying the cause of the blockage and addressing it can help prevent further issues with the plumbing system.