If the cabinet under your kitchen sink is so full of cleaning supplies or pans that it's running out of room, you may be frustrated with the plumbing pipes that take up so much space. The pipe that hangs low under the sink is the P-trap, and although it takes up valuable room in the cabinet, it's essential for the proper working of your plumbing. Every drain in your home should have a trap, although most of them are out of sight. Here's some information about the purpose of the trap and when it can give you problems.
Why The Trap Is Important
A reason drain pipes need a trap is to keep sewer gas from wafting out of the drain and fouling your house. The curve in the pipe that makes up the trap is designed to hold water every time water goes down the drain. Most of the water goes all the way through, but enough remains in the trap to form a seal that blocks sewer gas from coming out of your kitchen sink.
Another reason a trap is useful is that clogs often collect in the trap first, where they are much easier to remove than clogs that make it deep into the drain. A trap isn't completely effective at preventing drain clogs, but when you notice your drain is slow to empty, you can check the trap first before you call a plumber. Also, the ability of the trap to hold solids is helpful if you drop a ring or other valuable item down the drain. If you turn the water off immediately, there's a chance the item will be in the trap where you can retrieve it.
When The P-Trap Might Give You Trouble
Traps can be made of steel or plastic to match the rest of the pipe. One problem with traps is that they can become stuck so you can't loosen the nuts. When you try to take the trap apart to clear a clog or retrieve a ring, the trap may be frozen in place. This problem is common with many plumbing parts, such as valves, that aren't used very often. Even a plastic trap can be stuck and impossible for you to remove.
You can try removing visible corrosion from steel pipes and then apply penetrating oil to loosen the nuts. If you can't make any progress, you should call a plumber to take the trap apart, because you can break the pipe if you apply too much pressure while trying to twist the trap off.
Another problem that can develop with a trap is when the water evaporates and sewer gases escape. This problem isn't likely to happen in your kitchen since you use the water almost every day, but if you're away for a long time and the water evaporates, all you have to do to fix the problem is run water down the sink to create a new seal and air out the room so the odor goes away.
It's also possible to develop leaks around the trap. The leak could be in the trap itself or from loose connections, but whatever the cause, you'll want a plumber to repair the problem quickly so the sink cabinet doesn't have water damage and attract bugs to your kitchen.