Recently I had a small opening made on the wall connecting my kitchen and dining area. There were two pipes, one vent and the other carrying water which were both cut ( initially they were going straight up) and they were re-routed to allow for the small opening. One week after that I have been having water hammer. After any faucet or flush is turned off the pipes starts vibrating vigorously. I read some of the site where it says to close the main water supply and then let the faucet drain at the lowest point and also open up other faucets, then close them and open up main water line to allow water to fill up where there might have been air. I did that but I think my main water line doesn't shut off completely, is it why the problem did not resolve? The handy man said he has similar problem when he tried to cut off the pipe, was not able to shut off the water completely. Do you think has to do with the pipes that were cut and re-routed? What should I do? This problem has never occurred before! How do I get rid of this noise? Some times it even comes again much later after the faucet has been closed. Please help!