this is probobly a reflection of your water pressure - -you may try a "ballofix vale"
this is a small isolating valve fitted to isolate the supply to the toilet-- fit it and try turning it down a touch- obviously the toilet may take a little longer to fill.
A new installation should have isolating valves fitted anyway
dave broadbent
June 2007
the rubber diaphragm inside may of gone hard, replace
hi-spec plumbing
June 2007
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