when were s traps banned

When Were S Traps Banned? [Traps Made Simple]

In light of security concerns, numerous governments throughout the world have outlawed S traps, a kind of piping device that was often utilized in history. When were S traps banned? The hazards they presented as well as the laws that eventually led to their outlaws, will all be covered in this article’s exploration of the background of S traps as well as the reasons they were prohibited.

An “S” Trap: What Is It?

A plumbing trap is a bending piping drainage part used in buildings. Its purpose is to provide a watertight seal and prevent sewage gases from coming back into the structure through the sewer drain pipe system.

Sewer gasses are stopped in basins as well as other pipework by a catch called an S-trap. Gases cannot pass up through into the drain because of the drain plug created by the S-shaped tube design, which holds wastewater before something descends to the sewage line.

When Did S-Traps First Become Popular?

This S-Trap was state-of-the-art equipment in 1775, the year it was created. A Scottish watchmaker Alexander Cummings contributed to the development of running water by bending the pipes beneath a toilet.

The s-innovative bend’s construction naturally absorbed water to create the essential trap sealing. That although Alexander’s S-Trap was indeed a positive step, the barrier was extremely susceptible to siphonage. Therefore it only consistently prevented sewage gas. Plumbers began mounting crown outlets on S-Traps to prevent the siphoning issues.

When were S Traps Banned?

The banning of S traps occurred sooner than you would have thought, albeit there is no precise date for this. In reality, S traps were outlawed in the early part of the 20th century. In 1948, S traps were prohibited in New York State. Numerous other cities and counties have now adopted the same policy.

S traps were formerly as prevalent as P traps. But as days progressed, individuals became aware of S traps’ shortcomings. Due to several concerns, S traps eventually became prohibited.

What Caused the Prohibition on S Traps?

In the United States, this “S” trap is not permitted under the Uniform Plumbing Code. This is to ensure that methane (a byproduct of sewage) gases out from the “S” trap won’t suction or suck the liquid out of the traps and into the house instead.

Water is frequently sucked out from S-traps by this method. Sewer fumes are not intended to be able to travel through the liquid inside the historical low of any trap. Yet, if you flow water through an S-trap, the stream’s velocity can pull the entire liquid away from the catch. As a result, the seal is broken, allowing sewage gases to rise into the lavatory.

A potential health risk exists with this unfilled trap. Inhaling leaking sewage gases might risk your health, but when they are volatile and come into contact with a spark, they could explode. They might not even harm you directly, based on how strong the gas is. However, they will stink up your restroom.

Running the faucet very gradually may be capable of supplying plenty of liquid to shut off the leak in the near term. The longest single remedy, though, is to request that the plumber repair the catch and update your house to construction code requirements.

 What Drawbacks Exist with S Traps

What Drawbacks Exist with S Traps?

Throughout this part, we’ll talk about the S-difficulties traps with plumbing systems and why it’s prohibited by current plumbing rules.


S trap devices frequently experience clogs as a concern. The reason for this is that these circuits have the propensity to gather debris, including hair, soapy residue, as well as other impurities, which can ultimately accumulate and result in a blockage. As a result, this could cause sluggish drains, including overflow bathrooms or bathtubs.

Sour Odors

S traps frequently have odor issues as well. Since wastewater may accumulate over a long time and begin to stink, the system has been designed to contain it.


A further problem using S traps is leakage. This happens because the system’s gaskets may deteriorate or wear with time, which might result in water leaks.


A piping airlock occurs when the air becomes trapped and can lead to a number of issues. Water flow may be hampered by airlocks because of a drop in hydraulic pressure. Airlocks could also encourage the growth of germs as well as other contaminants, contaminating the groundwater and posing health risks.

Accumulation of Sewer Gas

The S-trap is prohibited because it may result in a hazardous accumulation of sewage gas. Methane, co2, and various dangerous gases make up sewer gas. If such gases enter a living area, they may be potentially harmful to humans. An unhealthful living condition may result from the S-trap allowing sewage gas to leak out.

Ineffective Design

The obsolete construction of S traps is among its main issues. They are less effective than more recent P-traps. Such P-traps are made to decrease the volume of water left sitting in the trap, avoiding obstructions and leakage.

What Laws Eventually Made them Illegal, and What Rules Did they Violate?

The capital of New York is among the most well-known instances of a county that outlawed S traps. In 1948, that state established legislation making it illegal to deploy S traps in residential development. S traps are currently forbidden throughout many parts of the country after several additional states and localities joined forces after that.

S traps have now been prohibited not only throughout the US but also in nations like Canada, Australia, as well as the UK. Each country has its construction codes, health and security rules, and restrictions that have resulted here to the banning of S traps, which differ widely.

What Functions of a P Trap

What Functions of a P-Trap?

S-traps were abandoned in favor of p-traps, especially under sinks, to solve the leeching issue. Two essential characteristics of a p-trap prevent diverting.

A blown pipe constitutes first. As long as there is no convective cooling or “sucker” activity required for siphoning, all gas levels within the drainage must be equal. The outlet end of the catch has also received an expansion. Gravity “pushing” liquid through into the tube is greatly less by the expanded pipe.

But a p-water trap can continue evaporation. Therefore, the risk of a dry catch cannot yet be eliminated by any “ideal” arrangement.

How Can an S-Trap Be Made Into A P-Trap?

Step 1: Take Out the Drain Cover

Before beginning, it is advised that you take out the sewer pipe. Your system might be harmed by any unexpected flowing water.

Step 2: Make Space for the Tube

Remove a portion of the valves in this stage to make room for the tube.

Step 3: Install the Tube

Put the pipe into the opening. A vent connection is required for the extended line.

Step 4: Reattach the Plumbing System

You need to reassemble everything now that our transformation is done. Connect the plumbing system to the top of the pipe and fasten it there. In order to check for leaks, switch over the flow. If not, you’re good to go!


Q: Do S Traps Exist Today?

A: S traps are not usually an employee in residential development. They are still present in a lot of older structures.

Q: Who Should I Get in Touch with to Get My S Trap Examined or Changed?

A: If you want your S trap inspected and to talk about replacement possibilities, get in touch with a qualified plumber.

Why S traps are not allowed Anymore? Have a look at this video as well!!!!!!

Video Credits – Got2Learn

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