Help! I moved into a condo and immediately noticed the clanging sound in my walls when I'd turn the water off.. happens with hot and cold. It's even louder when the toilets finish filling with water after a flush. A contractor friend went into the wall to be sure no braces had come undone. They hadn't. I spoke to the previous owners and they said they had a plumber come out to be sure the pipes themselves were ok; they were as well. I tried an air pressure fix I saw on line, i.e turning off the main water and open all faucets and toilets; it didn't work. It doesn't happen with the washing machine. I need help ladies and gentleman before it drives me crazy!

And nobody has even mentioned water hammer?
: The first thing I would do is to recharge the air chambers. We install air chambers on all lavatorys and the kitchen sink to reduce shock, vibration and noise. It could also be that a chunk of solder came loose and got caught in the bend of a 90 degree elbo and every time water rushes past the fitting it disturbs the flow. But I would try recharging first. Has this always been a problem or did it just start? Let me give you instructions on how to recharge your air chambers. Back in the 60's we were required to to put shock absorbers,(air chambers) on all bath lavatorys and kitchen sinks. Over time water and condensate built up in them and they must be recharged. First turn off the house at the main house shut off valve. Then open hot and cold faucets at the farthest bathroom to prevent air lock.(This is important.) You will find under each fixture little brass or chrome valves. These are called angle stops. With a small pail held under the angle stop to catch the run off look under the handle of the stop and you will see a nut with the stem running through it. This is called the bonnet packing nut. Put your wrench on it and back it off counterclockwise. Now open the stop and remove the stem and washer assembly, The stop will begain to drain. When it has quit draining reassemble the stop and move on to the next one. Do this on each one of your angle stops. There will be six of them. When you are done, close off the faucets you have opened, turn on the water to the house, and give yourself a pat on the back. You have just recharged your air chambers. If that don't get it click on back and we will go to step#2. Good luck and thank you for rating my reply.