What is a P Trap

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What Is A P-Trap And Why Do Sinks Have Them Have Them

If you open the cabinets under sinks in your home, you will notice an odd-shaped drainpipe. It extends from the drainage assembly to the wastewater system in the wall. In most cases, you won’t pay too much attention as to why this drainpipe has a P shape.

You would presume that it has a specific purpose because plumbing is designed with practicality in view rather than aesthetics. However, if you have ever stopped to wonder what this pipe does, read ahead. This bent section in the drain pipe under your kitchen sink is referred to as a P-trap. It has a vital function in your kitchen’s daily workings without you even being aware of it.

What Is The Purpose Of A P-Trap?

So what exact function does this P-trap have in the kitchen plumbing? There are three primary reasons:

Building codes require that P-traps be installed in locations where there are open-drain lines to expel the wastewater into the waste vent system.

The P-trap’s role is to trap solids, which can clog the sewer line or drain. They also help trap small valuable items like finger rings, which might have slipped into the drain when you are doing the dishes.

This trap stops the sewer gases from backing up into your home via the drain line.

P-Trap Materials

The P-trap can be made of steel or PVC. The latter is typically used in locations where there is exposed plumbing, as it is far more attractive. PVC fixtures last longer, and the installation is straightforward, as no tools are required.

Plastic P-traps have nylon connectors that can be easily fastened by hand just by twisting the plastic nut, making it easier for homeowners to handle it as a DIY project. 

P-traps that have not been correctly installed or serviced can lead to significant problems in the sinks; other systemic issues can arise as well. This makes it necessary to hire a professional plumber for P-trap installation.

How the P-Trap Design Works

A P-trap combines two 90 ° joints with the horizontal overflow pipe, which gives the whole unit a “P” shape. One 90 ° joint exits the sink drain and is connected to another with a water seal feature that permits the water to flow smoothly into the overflow pipe, without allowing a backward flow toward the sink. This prevents sewer gas from escaping into your house. The noxious gas has a rotten egg smell, which can also be poisonous and explosive. The traps installed in the plumbing lines form a water barrier within this P-trap. It also has a clean-out tap at the bottom that you can use to remove any clogs formed inside.

While P-trap installation is not very complicated, you still need to follow building codes while installing it. For example, if you have multiple sinks in a washroom, you can install only three of them to a single P-trap. Since there are certain specifications to follow with P-trap installation, its best to hire a professional plumber.

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