The toilet in our main bathroom lets out a shrieking, or high pitched tone whenever water is run anywhere else in the house. The only way to get the noise to stop is to either stop running the water, or go into the bathroom and flush the toilet. What is causing this, and more important, (for our sanity) how do I fix it. Thank you for any insight you can give me on this matter!
It sounds like you have a bad fill valve in the toilet. The fact that flushing the toilet makes the sound go away is a clue. As a first step, I'd replace BOTH the fill and flush valves in the toilet. These are inexpensive (about $15 - look for the Fluidmaster brand) and see if that stops it.