What Is a P-Trap, and Why Do I Have One?


Sometimes when dealing with a leak or a drain clog, it can be the first time a homeowner really pays close attention to their kitchen or bathroom plumbing system. This is sometimes the moment when people realize there’s a strange dip in their sink plumbing, whether you’ve got a pipe made of PVC or copper, it’s usually going to look like this.

This is not overengineering! Before you try to remove these pipes yourself and fix the “problem,” we’d like to talk to you about what this is and why it’s there under your sink. This is what’s called the “P-Trap” and it’s an excellent bit of engineering that deals with a common plumbing problem with just a little bit of gravity and water.

This is not the only clever thing throughout your plumbing system. There are many little bits of knowledge that a master plumber has to make your Garfield plumbing system work better and smarter. Let’s explore one of them today.

The History of the P-Trap

The history of plumbing is fascinating, especially as it relates to homes. Modern plumbing advancements like sewers and residential main water lines are only a few hundred years old. Many older homes might have been retrofitted with sinks and drains that link to a sewer system in the 20th century, even if the bones of the house are from before those systems existed.

Sinks, faucets, and drains have always worked together to move wastewater away from your house. The faucet gives you clean water, the sink lets you use the clean water, and the drain allows the clean water to be sent away.

But that begs the question, why does your drain not smell like the sewer it’s connected to? Well, they used to until the invention of the P-trap!

How a P-Trap Works

P-traps use two main methods to keep sewer gas from creeping up into your kitchen and poisoning the air. These methods are a liquid barrier mixed with gravity to hold it in place. We’ll explain down below.

First when you run the tap, a bit of water gets trapped in the P-trap (hence the name). That water gets caught there via gravity, since it can’t climb up in either direction, or until you send more water down the drain.

Gas can’t move through a barrier like water, so that water effectively halts the passage of sewer gases from infiltrating your kitchen or bathroom, leaving things smelling nice and clean. No electricity or complex technology, only gravity and water are required!

Do You Need a P-Trap?

Does your drain pipe lack a P-trap, and it’s constantly smelling foul? Then you might be the perfect customer for a p-trap installation. These only take a few minutes and a master plumber is going to be able to do this affordably and reliably. It can make a huge difference, and it will last for years in the future.

Call for Professional Help If You Need It

Don’t try to install a p-trap on your own. A pro will know what kinds of pipe materials to use, the correct size of them, and even the proper layout to leave space under your kitchen sink for cleaning materials and other things.


Join the Jake's Heating, Air & Plumbing VIP Club

Let us reduce future repair needs and keep your HVAC systems operating at peak performance throughout their lifespan.

  • Priority Service
  • Annual System Cleaning
  • Member-Only Discounts