A pop-up drain is a type of sink drainage system that uses a plug to seal the drain. The plug is connected to a lever, which when lifted, opens the drain. Pop-up drains are commonly used in bathroom sinks and bathtubs. While they are effective at keeping water from draining out of the sink or tub, they can develop leaks over time. There are several reasons why a pop-up drain might leak.
One reason for a leaking pop-up drain is an improperly installed or damaged gasket. The gasket is the rubber seal that sits between the popup assembly and the sink basin. If it is not properly seated or if it is damaged, water can seep through and cause a leak. Another reason for a leaking pop-up drain could be corrosion of the metal parts. Over time, exposure to water and humidity can cause metals to corrode and break down, which can lead to leaks.
If your pop-up drain is leaking, try checking the gasket first. If it appears to be damaged or not seated correctly, you can try replacing it with a new one. If that doesn't solve the problem, then you may need to replace other parts of the popup assembly such as the linkage or stopper rod. In severe cases, you may need to replace the entire popup assembly.