The answer to 'when to replace drain' is that you generally need to replace a drain when it is clogged, leaking, or damaged beyond repair. Over time, drains can become corroded, cracked, or obstructed, which can lead to water leaks, slow drainage, and other plumbing issues. It's important to address these problems promptly to prevent further damage and potential water damage in your home.
Signs that it may be time to replace a drain include slow or backed-up drainage, persistent clogs, visible cracks or damage, and frequent leaks. If you notice any of these issues, it's best to have a licensed plumber inspect the drain and determine if replacement is necessary. They can assess the condition of the drain, identify the root cause of the problem, and recommend the best course of action.