Can there be a leak only when the tap is open?

[TonyBronx]

Hi All,
I mean that could also indicate a leak of dirty water but I cannot see it anywhere.
What I hear is the sound of dripping water after I was in the upstairs bathroom. I don't here it upstairs but downstairs like water dripping every 5+ seconds on the ceiling plasterboard but it could well be the noise of something else the pipes themselves. The noise slowly goes away.
I don't know.

 

[Chuck]

If it happens when you run a hot tap but not when you run a cold tap, then it's likely that you are hearing the hot-water pipework, which expanded slightly when you ran the water, slowly contracting as it cools down again.

 

[TonyBronx]

If it happens when you run a hot tap but not when you run a cold tap, then it's likely that you are hearing the hot-water pipework, which expanded slightly when you ran the water, slowly contracting as it cools down again.

good idea. I am going to rule the leak out by running the cold water.