I have recently developed a high pitched “squealing” when using cold water in my 6yr old house. It does not seem to be isolated to a single source. Is very bad when running the sprinkler alone and horrible when a toilet is flushed while sprinkler on. Also very bad when toilet and tap are on together. Changes pitches as different levels of water are used. Any suggestions as to what may be causing this and how to correct.
Sounds like it MAY be a toilet ballcock washer. Turn off the water supply stops to all your toilets and see if you have squeeling with sprinklers on. If their is no squeeling in the pipes, turn toilets on one at a time until you find which one it is than replace that ballcock.