: Our house is only 3yrs old but when we flush the toilet upstairs in the masterbath, we hear banging in the pips as the water goes down. We had the builders come back, and they were willing to cut out the wall downstairs to see if they could fix it but they said they couldn't garuntee if they could fix the problem. I'm open for any advice.
If the problem is with the drainage piping, you have a problem that can be solved by opening the walls, locating the loose piping and having it secured.
If the problem is with the water supply line, you may have too much water pressure within the system, loose piping in the walls or maybe even a faulty toilet fill valve. A plumber should investigate, the builder may not know exactly what to look for.
Good Luck & Happy Holidays. e-plumber