There is only one way to permanently solve this problem and that is to get rid of the cistern ballcock you have at the moment.
First you have a worn valve seating which is not shutting of the water supply properly.
Second, it sounds as though you are in a high water pressure area which makes your valves scream as they are slowly shut down.
The only answer is to fit a TORBECK valve which are available as both a side entry or bottom entry version.
They are capable of handling pressures from 1.5 to 200psi.They have a positive hydraulic closing action and are noise free.
Put 'torbeck valve' in your browsers search bar for further details and suppliers. Should cost you less than a tenner regardless of which version you require.
I've been using them on my cisterns and header tanks for the last 30 years.
Cledlyn, July 2008
