⚠ Safety note: This guide involves working with plumbing. If you're not completely sure about every step, stop and call a licensed professional. Before you start, always switch off the power at the breaker or close the main water/gas valve.
1 Prepare for safe work
Close the corresponding valve, turn off the electrical power to the appliance if any, and wait for the water to cool. Protect the floor with a bucket and rags and photograph the initial position of the joints.
⚠ Warning: Do not push sharp metal deep into the waterproof joint around the drain; a punctured membrane causes hidden leaks.
2 Determine the pattern of the problem
Remove the grate wearing gloves and photograph the position of the insert or cup that holds the water seal.
3 Check the most common cause
Remove hair, soap, and sludge mechanically, wash the accessible parts with a mild detergent, and clean the edge of the drain.
4 Apply the appropriate solution
Return the insert completely into its seat, pour water, and check the drainage and that the odor does not return.
? Tip: Photograph the initial state and change only one thing at a time so you know which check really affected the result.
5 Test the result and set a boundary
Assemble the connections without overtightening, slowly open the water, and monitor for leaks, pressure, and drainage for at least a few minutes. If the problem returns, close the supply and call a plumber.