Foghorn noise that vibrates after flushing toilet

[Kee]

Can anyone help please. The noise comes after you flush the toilet and can go on for a good minute or so. And it's so loud like a fog horn, one long loud sound - and you can hear it all over the house. People talk about water hammer (which it doesn't appear to), and making sure the pipes aren't touching or vibrating - but we've done all this and the noise is still horrendous. Can someone please suggest something? Huge thanks.

 

[p the plumber]

Yup, its time for a new float valve assembly, its the washer hardened off in the old one thats is causing the vibration noises, I just instal a new assembl as they are cheap enough, be sure to get a high pressure rated one if connected directly to mains pressure incoming water (denoted usually by red or blue colour), not so important if fed by low pressure header tank in the loft

 

[Kee]

That is so helpful - thank you so much.