The answer to 'how to maintain drain trap' is to regularly clean and inspect the drain trap under your sink. The drain trap is the curved section of pipe under the sink that holds a small amount of water to prevent sewer gases from entering your home.
To maintain the drain trap, first unscrew or disconnect it from the sink drain and the wall or floor drain. Inspect it for any clogs, debris, or damage. Use a wire brush or plumber's snake to clear out any buildup. Rinse the trap with water to remove any remaining debris. Then, reattach the trap, making sure all connections are tight to prevent leaks.