Noisy water pipes.

[Denisdiamond]

Every time I flush the toilet ,my water pipes make an horrendous rumbling noise which is only alleviated a little by turning on the cold water tap. I live in a flat ,so I can imagine what this noise must be like at 3 in the morning for my downstairs neighbours! Can you help me get rid of the noise? Thank you.

[Mosaic]

This might be related to your toilet cistern's flush control - whether a ballcock or one of those plastic-bag thingies. I had exactly waht you describe with my downstairs. I replaced the suite when redecorating and the problem went away.
You could try replacing the internal flush mechanism of the toilet - a weary job especially if you haven't done it before. You can alos get valves that fit onto the nearby pipework that claim to cure the issue (I have never tried this).
Is it your own property or is this your landlord's responsibility? Just a thought.

[boxtops]

Agree with mosaic, this could be the landlord's responsibility if your property is rented, or your management company if you own. Worth looking at your paperwork.

[AlBags]

Try finding the mains stopcock .. and turning down so it is open 3/4-1 turn only.
It is water hammer.

[munchie63]

I had a similar problem, and found it was due to the toilet cistern. when the toilet flushes and your ballcock etc go up and down (oohermissus) if it scrapes against the inside of the cistern you get that horrible echoing noise in the pipes.
You're looking at around £10-15 I think for a new cistern set, but they can be a bit of a fiddly pain to fit. you could try adjusting it slightly yourself first and see if that works.

[AlBags]

It is the valve/seal chattering on it's seat against mains pressure that creates the noise.
Replacing ballcock valve for a Quiet fill type and damping down mains stopcock will help as I stated earlier.

[Mosaic]

FYI albags - my downstairs had a quiet-fill and we still got water-knock.

I had another practical thought about Denis's problem - till fixed, avoid using the flush at night by having a bucket (or watering can) of water on standby. Use this to flush down after jobs big or small, and at least you know you aren't rousing the whole block, till the problem gets fixed.

[Denisdiamond]

Thanks everyone for your solutions. Will give them a go.