What Are the Causes of P-Trap Damage?

Freezing

• If a sink is mounted on the inside of an exterior wall -- a wall with one side on the outside of the home -- it is possible for its P-trap and other interior pipes to freeze if you let your home get cold enough inside. This can be a problem for people who spend time away from their homes in winter when temperatures may dip well below freezing. The frozen pipe can crack as it thaws. While it is more common to see this happen to a pipe that is in the wall, because that pipe will be exposed to colder temperatures, all it takes is your home heating to fail for the inside temperature to drop low enough that the pipes can freeze.

Remote Damage

• Water dripping from the low point of a P-trap might not actually mean there's damage to the P-trap. If you see the water dripping only around times you’ve run the faucet at that sink, it’s possible that one of the pipe connections is loose or improperly caulked, and water is leaking out from there and running down the pipe to the bottom of the P-trap. Check all of the connections on both sides of the P-trap and all the way to the ends of the attached pipes to see whether this is what’s happening, and tighten or otherwise seal any that are leaking

Chemical Drain Openers

• One of the reasons chemical drain openers are unpopular is the amount of damage they can do to pipes. These are corrosive liquids that eat away at clogs. It’s possible that a chemical drain opener has eaten away at the inside of the P-trap in question. Rather than use chemical drain openers, use a combination of baking soda and vinegar, or remove the trap and use a drain snake to work on clogs that are behind the wall.

Snakes and Augers

• If you use a drain snake, also called an auger, be sure you do not stick it down through the P-trap. Not only will you have to deal with trying to get it to wind its way through the curve of the trap, but it can mar the inside of the pipe. Do this often enough, and you could end up with a crack.

Rats

• An unpleasant but possible scenario is that a rat has gnawed at the P-trap for whatever reason. While there’s nothing about a P-trap specifically that would attract rats, they're prone to chewing on whatever they find, including plastic pipes. So if you see exterior damage to a P-trap and can’t find any other explanation, you might want to ask a pest control company to inspect the damage.