Please help! This is driving my wife and I nuts. We've just moved into a house with a small downstairs toilet. At night for some reason the cistern in the toilet starts screaming. The mains water pressure tap is in this toilet too, if I turn that down it stops. But then we have no pressure in the sinks and the shower so I have to turn it back up again in the morning. It's a small enclosed cistern. Can I stop this and still keep good pressure to the rest of the house?

What is your water pressure? If ypou don't know gio buy a small gauge and connect it to your outside spout or wash sink. You may have too much pressure or just a fill valve that is crapping out on your. If so replace with a Fluidmaster 400a.

I agree with Bob, high water pressure will cause this problem, check your water pressure it should be 45-60 psi see the image for the gauge, if water pressure is OK do as Bob say replace the fill valve, good luck

John