Hope some one can help. I have just had a new main pipe laid through my driveway due to a leak. Now when I turn on the cold tap on in the bathroom it makes a loud thumping noise, but not all the time and not always the 1st time I turn the tap on. This morning I turned it on and it was fine and then went back in 10 minutes late and turned it on and it made the thumping the noise. We have also just put in new taps in the bathroom.

Does it thump repeatedly or just once? Is this a single handled valve? Back to you, Tom

Well, say it sounds like someone’s drilling into the wall so I guess it would be a repetitive sound.



Its not a single handed valve

Sounds like you might have a small pebble lodged in the seat
Shut the water off and open up the cold side of the faucet. Place a pan over the open faucet and turn the water back on on for a moment to flush out the supply. Reassemble and test. Let me know if that fixes the problem. Good luck, Tom