After no water has been run in my house for a little while, when I turn on the water, there is a rumbling sound in the pipes. It lasts maybe a couple or a few seconds and then goes away. If I turn the water on quickly, the rumbling stops pretty quickly. If I turn the water on slowly, the rumbling lasts longer. If I turn the water on slowly and then turn it off, the rumbling continues for a long time, maybe 20 to 30 seconds or longer — I make it stop in this case by turning the water back on.
As nearly as I can tell, the sound is coming from somewhere near my water meter. Anyone have an idea of what might be causing this?