My husband and I recently bought a house and noticed that the downstairs bathroom makes a hight pitched noise. It is very random, but stops when water is used or when the water shut off valve to the toilet is touched. It has gone from occasional to several times a day and is even annoying us at night! We can hear it all the way up in our bedroom! What is the deal? I just had a plumber here to help with a few problems and don’t feel like paying hundreds of dollars again.
Do you have a PRV valve on your main water line, if you have turn down press, if not get one put in. Sometime a bad washer on a ballcock are valve will sing with high press. try turnning valve under toilet down a little and see if that helps, let me know.