WHEN I FLUSH MY TOILET AS THE CISTERN IS FILLING UP IT STARTS TO MAKE A WHISTLING NOISE FROM THE PIPE. THIS CAN BE STOPPED BY HOLDING THE FLOAT BALL DOWN OR UP BUT IF IF T LET TO FLOAT ON ITS OWN THE WHISTLING CARRIES ON FOR A MINUTE UNTIL THE CISTERN IS FULL ONCE MORE

MR JONES, September 2005

It sounds like your toilet is on mains pressure, you will need to fit a reducer, to restrict the flow, slow it down, either that or if it is fitted with an isolating valve, restrict the flow there, but that is not ideal, as it may cause a different noise.

David C, October 2005