I have a problem. When I run a shower or when I drain the tub on the
top floor, I hear dripping on the floor below. If i put the plug in
first, and then run the water, I hear no dripping. This leads me to
believe that the problem is not with the water supply but with the
drain. Forgive me if I'm using newbie terms, I really don't know what
I'm doing. A colleague of mine, who just moved into a new house has the
same issue, and he feels that it is just water dripping within the
trap. As info, my house is about 7 yrs old but I've only been in for 2
months, and the dripping has happened the whole time I've been there.

Any ideas? Thanks very much in advance.