Updated on: January 12, 2026
You can’t see most of the plumbing pipes in your house, and that’s a good thing! (Unless you want an industrial appearance for home décor and you don’t mind guests constantly tripping over exposed pipes.) However, there’s one important exception, and we bet it just popped to mind: the bent piece of drainpipe directly under your sinks.
This component is called the P-trap, and it serves an important function in your household plumbing. While it is an old invention, it remains the most effective way to use gravity to keep your home sanitary and pleasant. But what happens when it stops working, and how do you know if your home is up to code?

