Understanding P Trap and S Trap in Sanitaryware – A Simple Guide

When selecting a toilet or water closet for your bathroom, you might hear terms like P Trap and S Trap. These aren’t just plumbing jargon — they play a crucial role in how your toilet connects to your drainage system and keeps your bathroom odour-free.

Let’s simplify what they mean, how they work, and how to decide which one fits your bathroom layout.

What Exactly Is a Trap?

In sanitaryware, a trap is the bent section of the outlet pipe attached to your toilet. Its job is to hold a small amount of water that blocks unpleasant gases and odours from rising through the drainage line.

Among the different trap styles used, the most common are the P Trap and the S Trap — each suited for a specific type of bathroom installation.

P Trap – For Wall Outlet Drainage

A P Trap gets its name from its “P-shaped” bend when viewed from the side. It has a horizontal outlet that connects to a wall drainage system rather than the floor.

Best suited for:

• Wall-hung toilets
• Floor-mounted WCs with wall outlets

How it functions:
Every flush leaves a thin layer of water inside the trap curve. This water seal stops sewer gases from escaping into your bathroom, keeping the environment fresh and hygienic.

Why it’s preferred:

• Sleek and space-efficient design
• Perfect for modern bathrooms with concealed plumbing
• Simple to clean and maintain

S Trap – For Floor Outlet Drainage

An S Trap looks similar to the letter “S” and is designed with a vertical outlet that connects directly to a drain on the floor.

Best suited for:

• Conventional Indian bathrooms
• Areas where the plumbing line runs below the floor

How it functions:
After each flush, a small amount of water remains in the bend to block odours, while waste moves directly down into the floor drain.

Why it’s preferred:

• Works perfectly with floor-mounted toilets
• Highly effective for older plumbing systems
• Provides a strong downward discharge

P Trap vs S Trap – The Key Differences

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How to Choose the Right Trap

Your bathroom’s drain outlet position is the deciding factor:

• If the outlet is on the wall, go for a P Trap.
• If the outlet is on the floor, choose an S Trap.

For new constructions, you can plan the plumbing layout based on your preferred toilet design. But for existing bathrooms, it’s always best to match the trap type with your current outlet position to avoid modifications.

Final Thoughts

Both P Trap and S Trap are vital components that ensure your bathroom remains clean, odour-free, and functional.
While P Traps complement contemporary wall-hung toilets, S Traps continue to be the trusted choice for traditional floor-outlet systems.

Knowing the difference helps you make an informed choice — ensuring your bathroom design is not only stylish but also perfectly engineered for performance.