Air Lock in Water Supply to WC?

[Phil Richards]

Hi

Most (but not all) times our WC is flushed a loud noise coming from the water supply pipe starts as soon as the cistern fills up. It is usually possible to stop this by quickly turning on the adjacent cold tap on the wash basin on & back off for a second or two. On some occasions this needs to be a second time or left running for about 30 seconds. Otherwise the noise carries until the cistern is about half full and then stops.

I have tried adjusting the water pressure up and down by a screw on the water supply pipe to no avail. Note that all the cold water supply for our flat comes off the mains, not from a tank in the loft.

Any ideas on how to cure this?

Thanks

[John]

water hammer - sometimes simply changing the ball float valve washer effects a cheap cure, otherwise google water hammer

[Set Square]

Sounds like the ball valve is going into spasm and turning the water on and off rapidly. I have one which does it very occasionally. I would suggest replacing the ball valve with a Torbek type which allows full unimpeded flow until the cistern is virtually full.

[Phil Richards]

Thank you John & Set Square for your help