What makes my water pipes whistle loudly?

Question

This just started and seems to be restricted to the flushing of any of my toilets and (coincidentally?) started just after I installed a new ballcock (can I say that here?) valve.

Answer 1

Make sure that the valve is open in its entirety. It sounds as though it may be reducing the flow by being partially closed. Try adjusting the valve and see if the noise disappears. Good Luck!