It's possible that there is an air pocket or a venting issue in your domestic pipe, which could be causing the water to back up and bubble up in the sink when you use the tap or washing machine. Here are a few steps you can take to try and resolve the issue:
Check the air vent: Under the sink, there might be an air vent that allows air to flow into the plumbing system, preventing airlocks or vacuum effects. Ensure that the vent is not blocked or clogged. You can gently clean it to make sure air can escape freely.
Plunge the sink: Try using a plunger on the sink to see if you can dislodge any blockages or push the air pocket through the pipes.
Run water in nearby fixtures: Turn on other faucets in the house to see if running water elsewhere helps to dislodge the air pocket. Sometimes, this can create enough pressure to force the air through the pipes and release the blockage.
Run a hose down the drain: If you have access to a garden hose, try running it down the drain vent stack on your roof (if you have one) or directly into the sink drain. Turn on the water to create a forceful flow that might push the air pocket through the pipes.
Seek professional help: If none of the above methods work, it's best to contact a plumber who is experienced in dealing with air pockets and venting issues in domestic pipes. They may use specialized equipment or techniques to dislodge the blockage and restore proper drainage.
Keep in mind that plumbing systems can be complex, and attempting to fix the issue yourself could potentially cause more damage. If you're unsure or uncomfortable with the steps mentioned above, it's always best to consult a professional plumber to avoid any mishaps or further problems.