Oddly, our house has developed the strangest thing. It is only 12 years old and has worked flawlessly. BUT, this week we began hearing a sound, like a squeak, when the water is turned off at the faucets inside. It is not the typical water hammer which sounds like banging pipes. The cause? You best guesses invited. Best solution? Install a anti-water hammer device near the inlet from the street? All my years . . . and I have never heard one like this.