possible leaking problem?

Recently, when I turn on the hot water in my sink, I could hear the water dropping sound behind the cabinet. This does not happen when I turn on the cold water.

When I start running hot water, the water dropping sound starts. I keep the hot water running and did not hear the leaking sound. When I turn off the hot water, the leaking sound starts again.

What could be the problem?

Because the sound comes from behind the cabinet, I could not tell if there is a leak. Could it be an expansion of the pipe because of the cold weather and the hot water running through?

?!

leaking said:

Could it be an expansion of the pipe because of the cold weather and the hot water running through?

Click to expand...

Yes. Pipe expanding through wood sounds like that.

Hot water in plastic drains (ABS or PVC) will cause them to possibly make sounds if they're rubbing on something as they expand (when running hot) and then contract again (while cooling off).