Q:After I installed a low-flow toilet, a bad knock occurred in the pipe whenever the toilet was flushed. I figured it was water hammer, so a plumber friend installed a T-pipe arrester on the main line ...

Q: Every time I turn off the water faucet in my laundry room, it sounds like someone is banging on the wall. Is my house possessed by evil spirits? Please help; the noise is frightening my kids. A: ...