Taming a noisy drain

Q: How can I make a drain pipe quiet? Whenever a toilet is flushed or the shower is running in my parent’s house, the loud sound of running water can be heard. It even wakes them up at night. What’s the cause and how can it be remedied?

A: Noisy drains are a common problem that stems from the material drainpipes are typically made of these days. The most common is a kind of black plastic called ABS, and although it's tough, easy to work with and inexpensive, it also transmits the sound of flowing water remarkably well. Cast iron was traditionally used for drains, and though it blocks noise very effectively, it's expensive and troublesome to install. The only practical course of action at this stage is insulation of the space around the pipe. And depending on the situation, this may not be easy. Every drainpipe travels within a cavity of some sort. If you can stuff this space with fiberglass insulation it offers some relief. Trouble is, you'd need to remove the drywall to get the job done. And even then, the results won't be as silent as with cast iron. Another option is to encase the pipe in expanding polyurethane foam. It may be possible to do this by drilling holes in the drywall every 12 inches, sticking the nozzle of a foam can inside, then filling the space with goop. This would eliminate the need to tear down drywall, though it only works if walls closely surround the drainpipe.