A childhood belief about water towers

In my Nieghborhood there's about 20 kids that live(d) in it and we're all friends but wen we were in Elementary school we'd always go on bike rides together and there's a water tower right across the highway that's behind my house, that's where we usually rode our bikes to. There's a big door thingy on the side of the water tower so we thought that a guy lived there and we called him Walter Water, he couldn't talk and he couldn't come out cuz he would die if he came out of the water in the tower. so the only way he could communicate with us is if we banged on the sides of the tower and he'd answer back. But we did relize that our bangs echoed, and that no one was really banging back at us.