Cold pipe making knocking noise

25
Found 25th Jan 2013
Got a really noisy cold water mains pipe. When you shut off a water outlet, it knocks, kinda thuds. I read up about it and most places seem to think its pipe chatter. Its really noticeable when the cistern in the toilet has just filled.

Thing is, my water pressure isn't that high - just over 3 bar.

Any ideas?
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25 Comments
Living in Scotland probably doesn't help.
Pretty sure its nothing to do with my geographical location.

Obsessed.
moob

Pretty sure its nothing to do with my geographical location.Obsessed.



Just trying to help.
I am sure this is something to do with a valve near the bog, god knows why but we had a plumber about this years ago, and thats what he said, he changed the bog mech and it went.
aircanman

I am sure this is something to do with a valve near the bog, god knows … I am sure this is something to do with a valve near the bog, god knows why but we had a plumber about this years ago, and thats what he said, he changed the bog mech and it went.


Just fitted a new bog today, same issue remains. It can also happen when shutting off the cold tap in the kitchen.
Weird. Mine started doing that today. Assumed it may have been somehow related to last nights plunging temperatures.
Been doing it all day but have just run some water and it was a little better.
JonnyTwoToes

Just trying to help.


No, you're just being you, a bawbag.
Do you mean toilet?

We actually had the same thing in the bathroom. It was due to a 90 degree angle in the pipe not being supported and so was moving and banging against all other pipes and stuff around it. We had a plumber in to secure the pipes at every major bend and not had any issues since.
It looks like you may need a shock arrestor, not expensive, about £20.
No he means an old scrote
I think it air in the pipe. But its the mains pipe
Getting a new kitchen fitted soon, hopefully the plumber I hire will sort it.

Cheers folks.
It's a ghost stuck in your pipes.
Maybe it's your neighbour on a knockathon shagfest
just fixed this in my house. Look on screw fix for il for a show close toilet valve was £15 fitted it in 5 mins Hay presto .it just shows water down b4 shutting valve off look it up on YouTube its called water hammer
slow close I meant
It's called 'Water Hammer', it's due to air in the pipes. If it only occurs on the cold water taps fed from the main street you could try reducing the pressure by turning down the stopcock slightly.

How do you know it's 3 bar? A proper pressure test or what a boiler gauge tells you?

turning stopcock down does not reduce water pressure,you need to replace loose jumper on stopcock if all draw offs in property cause this bang
Sworld

It's called 'Water Hammer', it's due to air in the pipes. If it only … It's called 'Water Hammer', it's due to air in the pipes. If it only occurs on the cold water taps fed from the main street you could try reducing the pressure by turning down the stopcock slightly.How do you know it's 3 bar? A proper pressure test or what a boiler gauge tells you?


Stopcock only reduces flow rate, not pressure.

I fitted a pressure gauge to the outside feed, and it showed as 3 bar.
bendypete

turning stopcock down does not reduce water pressure,you need to replace … turning stopcock down does not reduce water pressure,you need to replace loose jumper on stopcock if all draw offs in property cause this bang


Had to Google that! Never heard of a loose jumper in that context!

Thanks, I'm getting the stopcock replaced soon, as its appears to have failed - bit of an issue yesterday as I had a failed service valve at the same time when installing new loo!
moob

Stopcock only reduces flow rate, not pressure.I fitted a pressure gauge … Stopcock only reduces flow rate, not pressure.I fitted a pressure gauge to the outside feed, and it showed as 3 bar.

why did you fit a gauge to the outside feed? oO

its the internal pressure that needs measuring surely
csiman

why did you fit a gauge to the outside feed? oOits the internal pressure … why did you fit a gauge to the outside feed? oOits the internal pressure that needs measuring surely


Its a hosepipe connection that comes directly off the mains inlet, so figured it would be representative of internal pressure.

Is that wrong?
aircanman

I am sure this is something to do with a valve near the bog, god knows … I am sure this is something to do with a valve near the bog, god knows why but we had a plumber about this years ago, and thats what he said, he changed the bog mech and it went.



Exactly the same here.

I still to this day cannot understand how such a little piddly value can create a jet engine volume noise in the house. Once replaced all good.
Let's hope a ladder isn't required to reach this pipe.
http://s3.favim.com/orig/44/gif-jack-nicholson-scary-the-shining-Favim.com-373435.gif
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