I just had my master bathroom and main bathroom completely remodeled. This included all new plumbing from the cold and hot water source downstairs because we also had all the walls open. I now hear a periodic knocking sound when the toilet or main shower is running. Also when you should the water off you hear a taping sound. It is driving me nuts. I do not believe he put in air chambers in the line. The contractor kept teeing off from valve to valve. With out pulling apart my walls is there anyway to fix it? I am sure my contractor will tell me they no longer use air chambers---Can I use mini arresters on the valves? Thanks for your help, Marc