Why is an S-trap illegal?

The purpose of a trap is to prevent sewer gases, and possibly vermin, from coming in to the home. Back to “S” traps – The reason “S” traps aren’t allowed is because they have the potential to suck, or ‘siphon’, water out of the trap as the water flows down the drain.

Why would you use an S-trap?

The mechanical purpose of the trap is to hold water to prevent sewer gases containing viruses and bacteria from entering the home through the drain. With an “S” trap drain, the trap is easily siphoned dry with each use and the water seal no longer exists.

Is an S-trap bad?

The “S” trap is prohibited under the Uniform Plumbing Code throughout the United States. This is because the “S” trap will siphon or suck water out from the trap which will end up releasing methane (sewer) gases into the home. So, it is a code violation and if you are doing remodeling, you will have to replace it.

Can I use S-trap for sink?

A trap is simply a configuration of the drain pipe underneath a sink or any other plumbing fixture. S-traps are no longer used in modern plumbing because the water can be sucked completely out of the trap allowing sewer gas to enter your home.

Why is it called a P-trap?

A P-trap gets its name because it combines two 90 degree joints with a horizontal overflow pipe and gives the entire unit the shape of the letter “P.” One of the 90 degree joints exits the drain of the sink and then is joined to another which contains a water seal system that allows for water to flow into the overflow …

Do shower drains have S bends?

The trap in the shower drain works like the one beneath the kitchen sink. The S-shape allows water to drain vertically upon clearing through the S-shaped curve rather than draining horizontally. The bottom area of the shower trap holds some water that seals the drain against sewer gases.

Where are S traps illegal?

Use of “S” Traps is both illegal and obsolete as plumbing fixture traps where a “P” trap is required. While not every S-trap will cause trouble, enough of them do that they are prohibited in new construction. S-traps are often installed in older buildings where there is no venting provided for that plumbing fixture.

How do you vent an S-trap?

You can’t vent an S-trap in this way because it drops immediately to the drain. If you run water through an unvented S-trap, the vacuum created in the pipe can pull water out of the trap, rendering it useless.

What’s the difference between an S-trap and P-trap?

With an S-trap, the drainpipe drops down from the sink and into a conventional trap. It then loops over and exits downward. In a P-trap configuration, the drain also comes down from the sink and into the trap, but instead of looping over and back down, the drain enters a horizontal run before exiting downward.