The problem is a little different than that but here we go. My brother lives in the bottom story of a two story apartment. Whenever his upstairs neighbor uses there water based appliances it sounds like a loud heart beat in the walls. Thump thump thump. I stuck around and listened to it and it sounds like it's only doing it when it's draining. I told him to tell the apt folks and it turns out he did and they told him they couldn't do anything about it. What could it be and could I do anything about it? He just signed his lease so he's going to have to live with it for a year if it doesn't get figured out.