Noisy water system

[genthon]

Each time we flush the loo there is an awful noise in the water pipe. Originally this happened each time the loo was flushed and running the cold tap for a few seconds got rid of it. Now it is happening a little while after the loo is flushed and the noise is horribly loud and fills the house! It's going to waken my guests at Christmas! HELP!!

[Clanad]

I'm assuming, of course, that plumbing systems here in the U.S., share similar characteristics with those in the U.K. Your description of opening the cold water tap seeming to affect the noise has nothing to do with the actual opening of the tap, per se. The fresh water and waste water have no common connections. However, when you open the tap, the water flows down the sink and probably helps to relieve a vacuum that may have developed by the flushing of your WC. This could indicate that the vent line for the system may be plugged or otherwise not working. This should be a PVC type line, probably a couple of inches in diameter running from a low spot in the waste water system to the roof (to vent sewer gases). In severe winters they can freeze up near the top since the humid gases are venting. This will block the line and create a vacuum in the entire system resulting in the noise you hear. Best of luck!

[derekpara]

Not an expert but I've had the same problem.This sounds like water pressure to me. As a first step try reducing the water pressure by closing the mains water tap to about half. It may take a little longer to fill the cistern but it might be easier on the ears !

[derekpara]

Forgot.

If you've got an isolator valve for the cistern you can close that off slightly instead, using trial and error.. Good Luck.

[stanleyman]

Sounds like water hammer, a hydraulic shockwave in the pipe usually started off by loose pipes with not enough clips. Solution, fit a water shock absorber or accumulator, change some of the copper pipe for plastic or fit more clips.

[moomoojaj]

Pick up a screwfix catalogue and order a Torbeck valve. Stock code 14716 for side entry or 19960 for bottom entry. they are quiet and quick.

www.screwfix.com

[genthon]

Thanks a lot everyone for your advice! We will try some of your tips and see what happens.