Please help me! I just moved into a newly built home a few months ago and noticed that when I turn off the water, there is a knocking sound in the wall. It knocks 2-4 times generally, but is not a banging sound. The builder sent out the plumber at my request and he said the sound is due to the quick shut-off. There was no air in the pipes. After he left, I noticed that even when I turn off the water slowly, there is still knocking. The builder is giving me a hard time about having the plumber return since he already said that there is not a problem. I don’t think this is natural. What is your opinion? Thank you!!