When a water closet's flapper is leaking, what should be done?

When a water closet's flapper is leaking, replacing the flapper is the appropriate action to take. The flapper is a crucial component of the toilet's flushing mechanism; it seals the opening between the tank and the bowl, allowing the water to flow during a flush and then sealing off to prevent leaks. Over time, flappers can deteriorate due to wear and tear, resulting in leaks that can lead to water wastage and higher utility bills.

Replacing the flapper ensures that the seal is restored, which eliminates the leak and allows the toilet to function correctly. Regular maintenance and timely replacement of worn parts like the flapper are essential for the efficiency of the toilet system. In comparison, other options, such as replacing the chain or adjusting rod guides, might not address the root cause of the leak, which is the flapper itself. Lightly sanding it with emery cloth could potentially damage the flapper further or not resolve the leak at all, making replacement the most effective solution.