The answer to 'how to maintain drain' is to regularly clean and maintain your home's drains to prevent clogs and keep them flowing smoothly. This involves using a drain snake or plunger to remove any built-up debris, using a drain cleaner solution to dissolve organic matter, and preventing future clogs by being mindful of what goes down the drain.
It's recommended to clean your drains every 3-6 months, or more frequently if you notice slow drainage or other issues. If you encounter a persistent clog that won't clear, or if your drains are backing up, it's best to call a professional plumber to diagnose and resolve the problem.