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What Is the Purpose of a Drain Trap?

Looking underneath your kitchen sink, you may wonder whether all that piping is really necessary. Seriously, it seems like an over complication of what should be a simple process and when it doesn't, and your plumber comes over and starts talking about a P-trap or drain trap, you might give up trying to understand. But never fear when Anta is near - In this article, we will explain to you the function of drain traps.

What is a Drain Trap?

Plumbing traps are those large squiggly pipes underneath your kitchen or bathroom sink. They are designed with the specific purpose to always hold some water that helps keep sewer gasses from escaping into your home, leaving a bad smell. Drain traps are actually present in all drains and it also traps debris from clogging deep inside the plumbing system.

When you enter a bathroom or kitchen that has not been used for a while and you note a bad smell, simply run the faucet for a short while to fill up the trap again and you will note the smell will go away.

Toilets also have drain traps - that is how water remains in the bowl.

Usually made from PVC, or more attractive steel, there are various styles of traps, and a City of Toronto licensed plumber will be able to advise which traps are permissible by the city code.


A P-trap is named after its shape, which combines a horizontal overflow pipe and two 90 degree joints. The water seal system prevents water from flowing backward into the sink, and this function helps prevent sewer gasses from entering the home.

Why Use a Drain Trap?

Sewer gasses contain several noxious odors, that apart from smelling vile, may also be poisonous or explosive. However, drain traps form a barrier to prevent the gasses from causing issues inside the home.

Installing Drain Traps

Drain traps are inexpensive and simple to install for an experienced DIY expert. However, when you take on the project, be sure to correctly join the pipes to ensure that you have tight seals that will help avoid leaks.

Before you get started though, check the local plumbing code to ensure that you install the correct style of drain trap. Once you have done that, also remember these two rules to stay on the right side of the law:

1. You may only install up to 3 utilities to everyone drain trap.

2. If you install the drain trap to an infrequently used plumbing line, apply a trap primer to help keep the seal in place.

When you think about it, plumbing really is a fascinating topic when you consider how plumbing systems are designed to use gravity, and how water and gasses work together with gravitational pull to operate in the background.

Need help installing a drain trap? Speak to Anta Plumbing today.

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