P-Trap vs S-Trap Toilets: What’s the Difference and Which One to Choose?

One area of consideration that many people overlook when choosing a toilet for their bathroom is the type of trap used in the toilet. The trap is integral to how waste is disposed of, as well as helping by preventing sewer smells from entering your home. Western toilets mostly have P-Trap and S-Trap. Knowing about the differences between these traps will certainly help you make the right decision for your bathroom setup.

What is a Trap in Toilets?

A toilet trap is a bend in the toilet’s plumbing that allows waste to move toward the drain while keeping smelly gases from coming back into the bathroom. Water resting in the trap forms a barrier that keeps sewer gases from rising into your house.

There are two types of traps found in toilets:

• P-Trap
• S-Trap

What is a P-Trap Toilet?

P-Trap toilets, like the Summer Wall-Hung P-Trap Toilet, feature a horizontal drainage system that runs out of the back of the toilet bowl. The pipe curves like a letter “P,” then directs into the drainage pipe on the wall.

How Does a P-Trap Work?

The P drain trap holds water in the bend of the pipe and creates a water seal that keeps sewer gases from entering the bathroom. This type of toilet is commonly used when the drainage pipe of the bathroom is behind the toilet on the wall rather than the floor. For P-trap toilets, the usual pit measure is 7 inches (180mm) from the wall to the core of the toilet waste outlet.

Where is a P-Trap Used?

- Wall-mounted commodes 

- Bathrooms with wall drainage systems

- Modern apartments and high-rise buildings

What is an S-Trap Toilet?

An S-Trap toilet, like the Athos One-Piece S-Trap Toilet, has a pipe that leaves vertically from the bottom of the toilet bowl. The pipe runs in an "S" shape before entering the floor channels connected to the drainage system.

How Does an S-Trap Work?

As with a P-Trap, the S-Trap toilet keeps water in the bend of the pipe to prevent sewer gases from passing through. These toilets are commonly used in older buildings or houses where a floor outlet drain is present. The S-trap toilets are available in a pit distance of 10 inch/250mm, 12 inch/300mm or 16 inch/400mm.

Where is an S-Trap Used?

- Floor-mounted commodes

- Ground-floor bathrooms

- Older homes with floor drainage systems

Which Trap is in Which Western Commode?

Western-style commodes have either a P-trap or an S-trap, depending on the orientation of the waste outlet:

• P-Trap Toilets: For wall-hung, wall-outlet toilets that pipe the waste horizontally connected to the wall.
• S-Trap Toilets: Used mainly in floor-mounted toilets, where the outlet is at floor level.
• Most floor-mounted toilets offer both options as well, such as the Ruhe Space One-Piece S-Trap Western Toilet or the Dune One-Piece P-Trap Western Toilet.

Knowing the drainage outlet position in your bathroom helps in selecting the right type of trap toilet.

Key Differences Between P-trap and S-trap Toilets

Which Trap is Better: P-Trap or S-Trap?

There’s no clear winner between the two — the choice depends on your bathroom's drainage system.

• If your drain is on the wall, go for a P-Trap toilet.
• An S-Trap toilet should be the option if your drain is on your floor.

P-Trap toilets are popular in modern homes as they save space and are easier to maintain.

What to Think About When Picking a P-trap vs S-trap Toilet

1. Check Your Drainage System: Know if your drainage outlet is on the wall or floor.

2. Bathroom Type: High-rise apartments typically have P-Trap toilets, whereas S-Trap toilets are generally used in ground-floor bathrooms.

3. Space Availability: P-Trap toilets are often preferred for compact bathrooms, while S-Trap toilets may require more floor space.

Maintaining P-Trap and S-Trap Toilets

Proper maintenance helps both types of toilets last longer and function smoothly.

P-Trap Toilet Maintenance Tips:

• Regularly clean the water seal to avoid blockages.
• Check for any leaks in the wall connection.
• Use mild cleaners to avoid damaging the pipes.

S-Trap Toilet Maintenance Tips:

• Clean the floor area around the pipe regularly.
• Inspect the floor seals for leaks.
• Use a toilet cleaning brush to clean the trap’s curve.

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Deciding if you need a P-Trap or S-Trap toilet is mainly down to your bathroom plumbing layout. The P-trap toilets are best suited for modern apartments which have wall drainage, while the S-trap toilets are suitable for older homes with floor drainage. If you are renovating a bathroom or building a new home, always check with a plumber to make sure you have the drainage set up before deciding on your plan. Explore Ruhe’s western commodes collection and choose whichever matches your bathroom’s drainage style.