When the toilet tank finisdes filling after a flush I hear a loud bang which appears to be coming from the cold water pipe within the walls. This occurs when either the upstairs or downstairs toilet is finished flushing and when the tank is finished filling. I thought the thumping may have been a faulty angle valve, however, changing the valves did not make the thumbing go away. I feel that the cold water pipe may have come loose somewhere within the walls. The fear of having to tear the walls apart to locate a loose bracket bothers me somewhat. Any suggestions would be greatly appreciated. Thank you.

Hi Watchdog...

Since this sounds like it is something relatively new at your house it makes me think that you may have lost the air in your air chambers inside the wall. Here, awhile back now, plumbers used to install 18-24" tall pipes with caps at the highest points of the fixtures and when they filled the system with water the chambers would fill with air and act as shock absorbers to help reduce any vibrations in the piping system when valves got shut off. After some time, these air chambers can fill with water and noises like you describe start to occur.

Here's what you need to do:

Shut off the main water supply into the home and then go around and open up all faucets in the house. Then you want to go to the new toilet angle valves and remove the toilet supply tubes. Leave the angle valves wide open.

Now you wait say a half hour or so and over that time water will fall out of the air chambers and air will replace the water.

Afterward, you will want to reconnect the toilet supplies and then close all faucets and then open the water main and test for any leaks. Bleed all the air/sediment out of the system by purging out the system at an outside faucet or a sink without an aerator. If any sink faucets clog up, remove the aerator and clean it to restore full flow back to the valves.

Then, test the toilets and see if the noise(s) are reduced or even eliminated... should be. If not, pop back and let me know and we'll go the next step... OK?

MARK

I did shut of the water source , removed the toilet water hoses (hose from valve to water tank) and opened up all taps, wainted for about twenty minutes, turned off the taps and turned on the incomming water source, this procedure did not rectify the water hammer problem. Now here comes the surprise, I decided to open up a bedroom wall ajoining the bathroom and locate the cold water pipe. This cold water pipe was slightly loose from the wall stud, however, the cold water pipe leading to the shower was in fact loose and was actually touching the wallboard. I banged on the wall board from the bathroom side and hold and behold I heard that thumbing/banging noise. I braced the offending pipe away from the wallboard with pipe retaining brackets, and as of this date (three days later no return of the noise) I also put additional brackets on the other cold water pipes. Now, there is a bit of a mess in the ajoining bedroom, but nothing a little bit of elbow greese and fill won't fix. Thank you for your assistance.