We have 2 bathrooms in 2 floors. When we open sink faucet of 2nd floor bathroom, we hear water dripping sound in the 1st floor bathroom. The sound is pretty significant. This has been happening since more than 3 years. However, we do not see any sign of leakage on the ceiling or the walls. This is a mystery to us as to where the water might be going. Can you please help?
This is a 2001 house.