We had redone 1 bathroom and had a little noise start up in the lines after completion.
When the water was turned on it would make like humming noise. Then we redid the second bathroom and the noise happens when we turn on the water anywhere in the house. And it is louder than it has been before.

Hey Merdy, ( Is that really your name?)
Humming=vibration in the line some place. Vibration=something in the line that's in there vibrating. If I were there the only thing I could do is what I'm going to advise you to do. To stop the vibration you must first locate the source. To do this you depend on sound and feel. Where is it the loudest? What pipe feels like it's vibrating the strongest? The you check out the fixture and faucet that's the closest. Let me know what you find but I can't help until I know what I'm dealing with. Good luck, Tom