plumbing dislodging p trap

What Is a P-Trap & What Does It Do?

Have you ever read a plumbing article, seen the term “P-trap,” and wondered what in the world they were talking about? Well, a P-trap is not something they teach you about in most schools (unless you went to a program related to plumbing or building construction).

That’s why we’re going to explain precisely what P-traps are, what their purpose is in your home (yes, your home has multiple P-traps!), and what typical problems can occur with P-traps.


If you look at the drain pipe under your sink, you’ll see a curve in the pipe that resembles the shape of a “U” or a “P.” That’s an example of a P-trap.

A P-trap is a bend in a drain and waste pipe with a specific purpose. That bend in the pipe contains a pocket of water, which blocks toxic, foul-smelling sewer gases (like methane) from traveling through the pipe into your home. Additionally, if you accidentally drop something down the drain (like a wedding ring), you can usually retrieve it from the nearest P-trap.

You can think of P-traps as useful barriers that block bad smells from “coming up” and prevent objects that shouldn’t be in your plumbing from “going down.” Most modern homes have P-traps under each toilet, sink, shower, and bathtub.


There are two problems that typically arise with P-traps, which we’ll cover below: clogs and dry P-traps.


Because of the way a P-trap bends, it’s easy for foreign objects to get wedged in the curve and create a blockage. This is especially likely if something has gone down the drain that shouldn’t be there, such as wet wipes, paper towels, or large quantities of hair.

Clogs in a P-trap can be easily removed by using a drain snake to reach in and tug or push out the blockage. If the clog is severe, you may need to detach the P-trap from its neighboring pipes and clean it.

Keep in mind: substances like grease, sediment, dead skin, and soap scum can build up in pipes over time and make clogs a more frequent occurrence. If you’re regularly getting clogs, and they’re occurring beyond your home’s P-traps, you may want to consider getting your drains professionally cleaned as a long-term solution.

Dry P-Traps

Evaporation is typically why a P-trap will dry up. However, it’s also possible for a P-trap to dry up due to other problems, such as a leak, a clog absorbing the water, or dry winter winds entering your plumbing pipes. Once the water evaporates or leaks out of a P-trap, you’ll begin to notice a horrible smell of sewer gases entering your home.

The easiest way to solve or prevent this problem is to run a gallon or more of water down every drain in your home about every three weeks. This is especially important during winter, when P-traps tend to go dry the most.

At The Rooter Works Plumbing and Drains, our Columbus plumbers offer quality drain cleaning and exceptional customer service. Having trouble with a drain? Give us a call at (614) 412-3324 or contact us online.