an "S-trap" refers to a specific type of plumbing trap used in drainage systems. An S-trap is designed to prevent sewer gases from entering buildings through the plumbing fixtures. It is named for its shape, which resembles the letter "S."

The S-trap consists of a curved section of pipe that retains a small amount of water after the fixture is used. This water acts as a barrier, blocking gases from the sewer line from coming back up through the drain. S-traps are commonly used in situations where the plumbing fixture is not directly connected to a wall, such as in freestanding sinks or basins.

However, it's important to note that S-traps are generally not recommended in modern plumbing practices because they can be prone to siphoning, which can lead to the trap losing its water seal. This can occur when water flowing through the trap creates a vacuum that pulls the water out of the trap, allowing sewer gases to escape. As a result, P-traps, which have a different configuration that reduces the risk of siphoning, are more commonly used in new construction and renovations.

Functionality of S-Traps

S-traps are designed to block sewer gases from passing through drain pipes back to a building . They work by trapping a small amount of water in the S-shaped pipe configuration, which acts as a barrier to prevent sewer gases from entering the building .

Regulatory Considerations

However, it's worth noting that S-traps are prohibited in Australia due to safety and regulatory risks . The National Construction Code (NCC) and other regulatory documents, such as AS/NZS 3500.0:2003, provide guidelines and requirements for plumbing and drainage systems in Australian commercial construction projects .

Alternative Solutions

Given the prohibition on S-traps, alternative solutions such as U-, J-, or P-shaped traps are commonly used in Australian commercial construction projects . These alternative traps serve the same purpose as S-traps but are designed to meet the regulatory requirements and safety standards in Australia.

In Australia, plumbing regulations and standards, such as those outlined in the National Construction Code (NCC) and the Plumbing Code of Australia (PCA), provide guidance on the appropriate use of plumbing traps, including the conditions under which S-traps may be used or replaced with more reliable alternatives like P-traps.