Musical Pipes

I do not understand why this condition comes and goes. It is sorta weird, but there are some things that one does that do not need to be announced. Now it seems the entire house knows when one is in the Powder Room. Its sorta like the creaky step that lets the parents know when the kids come home. I have found out if I run the water in the sink this conditions does not occur. Ha Ha the pipes the pipes are playing Danny Boy! Also known as water hammer. This is a common condition (mostly) with older galvanized lines. The sound is caused by a vibration, which is created when water and suspended gases (air) in the water cause the pipes to vibrate. Most galvanized pipe water supplies were built with some vertical dead end length of pipe that acts as a shock absorber, called "bumpers" (and here you thought that those pipes were a sign that the plumber was wasting material).