If you’ve ever meddled with home plumbing remedies, you’re sure to have noticed the S-shaped or U-shaped pipe underneath every sink. This seemingly inconsequential piece of plumbing is called the drain trap, and it plays an important role in the grand scheme of all things drainage-related.

Every single thing in your home that connects to a drain has a drain trap, including your toilet. These plumbing drain traps are designed with the curve they have so they can retain a little water in the pipe every time the drain is used. This is to make sure no sewer gasses escape the drain and enter your home.

When organic materials decompose, they break down to release hydrogen sulfide, also known as sewer gas. Unless the concentration of this gas is really high, it does little more damage than smelling bad. 

So if you ever enter any room with a drain and you notice it smells a little funny, the first thing you ought to do is check the drain traps to make sure they’re not dry. Dry drain traps allow sewer gas to escape, stinking up the room. Even if the traps are dry, the remedy is simply running the taps for a bit and filling the traps with water.

Where are drain traps located?

drain trap location

In some cases, like with toilets, the location of a drain trap is pretty obvious: you see water standing in your toilet bowl. However, in the case of other plumbing fixtures, such as sinks, the location may not always be so obvious.

Very often, sink drains are often hidden from view by cabinets. However, if you follow the pipes, you’re sure to come across that section of the plumbing where there is an S-shaped or U-shaped bend in the pipes. Even though the water may not be visible in this case, this is where the water is stored to deter sewer gases.

In addition to preventing gases from entering your home, sink traps also have an additional fixture to prevent food wastes, hair, jewelry, and other small objects from getting washed down the drain, preventing future blockages. If you have clogged drains, most traps can be easily dismantled for cleaning purposes and reinstalled again. Some even have self-clean-out capabilities.

In the case of larger plumbing fixtures, such as bathtubs, showers and washing machine drains, the drain traps are most likely not going to be visible at all, considering they are going to be hidden beneath flooring or behind walls. You’d have to cut into the walls or into the floors to reach these drain traps.

Types of drain traps

There are around 15 types of drain traps that are used in the construction industry. Among these, the P-types, the S-type, and the Q-type are what we see most commonly used in domestic construction. 

Other types of traps designed to collect water and prevent sewer odors from entering include drum traps, bottle traps, and gully traps. Shallow traps and bell traps are also commonly used, while elaborate traps like the intercepting trap are most suited for commercial buildings.

Public restrooms most often feature running traps, while building traps connect a building’s drainage to the sewer. Grease traps are designed to keep food grease and large chunks from entering and damaging the kitchen’s wastewater system. 

Floor drain traps and low-level bath traps are what showers and bathrooms in homes feature. 

Among all of these, the S-trap has been deemed illegal to use by the Uniform Plumbing Code all across the US. This is because the design is such that the trap siphons out water and releases methane into the home.

However, a lot of older homes still have S-traps. A P-trap is considered to be a far better option and ideal to replace S-traps with. This is because of several reasons. For one, the P-trap is more affordable than an S-trap. The design of the P-trap also makes it better at retaining water. In fact, a properly installed P-trap will never lose its water seal.

Read more: Guide to P trap maintenance

Maintenance tips

drain trap maintenance

Here are some simple maintenance tips for your home’s drain traps.

  1. All drains must be put to use regularly to make sure water is retained in the traps. A frequency of at least once a week is advisable. While the traps drying out may not cause any major damage, it will leave the area smelling bad.
  2. A common practice while going on long vacations is to cover drains with plastic wrap to ensure sewer gas odor doesn’t fill the house once the traps dry up. While doing this, don’t forget to cover floor drains and shower drains as well.
  3. Make sure you empty and shut off toilets before stuffing them with plastic wrap.
Know your plumbing: All about drain traps was last modified: October 14th, 2022 by Narayan Shrouthy
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I didn’t know there were so many drain hacks, though I’ll still give this job to my husband, haha