S Trap vs P Trap Toilets: A Complete Comparison Guide

Understanding the difference between P and S trap toilet designs is essential when planning your bathroom. These traps refer to the shape of the pipe that connects your toilet to the drainage system—an important plumbing detail that affects installation and layout. In the debate of S trap vs P trap, choosing the right type ensures your toilet fits properly and functions smoothly, whether it’s a floor or wall outlet system.

What is an S Trap Toilet?

An S-trap water closet connects to a floor outlet, where the internal pipe forms an S-shaped vertical bend that retains water to prevent odor backflow.

S Trap Toilets Are Commonly Seen In:

• Ground-floor bathrooms
• Older residential constructions
• Independent houses with vertical drain lines
• Homes designed with traditional floor-exit plumbing layouts

What is a P Trap Toilet?

A p trap toilet connects to a horizontal wall outlet, where the pipe bends into a P-shaped curve while maintaining the protective water seal.

P Trap Toilets Are Generally Preferred In:

• Modern apartments and high-rise buildings
• Bathrooms with concealed plumbing layouts
• Compact or minimalist interiors
• Back-to-wall or wall-hung wc p trap installations

This orientation supports cleaner aesthetics, improved wall alignment, and better maintenance access in contemporary bathrooms.

Related Read: What Is a Bidet and How Does a Bidet Toilet Work?

Key Differences Between S Trap and P Trap Toilets

If you are wondering which to choose between P trap and S trap, then the most significant difference is where the waste pipe leads to. Here’s an overview:

Related Read: Different Types of Commodes for Your Bathroom

Pros and Cons of S Trap Toilets

Advantages

• Gravity-assisted downward discharge supports smooth waste flow with efficient coordination between the toilet bowl and the toilet flush tank
• Suitable for homes with existing floor-line plumbing
• Requires minimal civil modification during replacement
• Compatible with most s type commode layouts

Considerations

• Limited relocation flexibility due to fixed rough-in position
• Seal-loss risk in non-vented legacy plumbing systems
• Exposed base may require frequent external cleaning unless skirted

Pros and Cons of P Trap Toilets

Advantages

• Generally more stable against trap-seal loss when vented correctly, especially in wall-mounted fixtures such as wall-hung toilets and urinal pot installations
• Enables wall-hung and back-to-wall installations
• Improves bathroom aesthetics and floor clearance
• Provides easier access through rear-panel maintenance points

Considerations

• Requires adequate wall support or concealed frame structure
• Converting a floor outlet to a wall outlet involves civil re-alignment
• Installation accuracy is critical to prevent misalignment or leakage

Related Read: Top Trends in Modern Commode Design 2025

Which One Should You Choose: S Trap vs P Trap Toilets?

Choosing between an S trap and a P trap toilet depends entirely on your bathroom’s existing outlet. If the drainage is on the floor, go for an S trap. If it’s on the wall, a P trap will work best. Picking the wrong trap for the outlet can lead to fitting issues and costly adjustments.

At Simpolo Tiles and Bathware, we always recommend checking your plumbing layout before purchase. To make it easier, our Virtual Space Creator tool lets you visualise different toilet styles in a 3D setup—helping you choose what truly fits your space.

Choosing the wrong trap type:

• P trap toilets are meant for wall outlets; they won’t align with floor outlets.
• S trap toilets are for floor outlets; they won’t fit wall outlets.
• Using the wrong type can cause poor connectivity and costly rework.

Forcing the toilet into position:

• This can break the seal, leading to long-term leaks and damage.

Not measuring trap distance:

• Always measure the distance between the outlet and the wall or floor before purchase.

Ignoring plumbing compatibility:

• Check your existing plumbing setup or consult a professional to avoid mismatch.

Skipping layout planning:

• Use tools like Simpolo’s Digital Showroom to visualise 3D bathroom layouts and ensure accurate planning.

Improper urinal placement:

• Leave enough space if you plan to install a urinal.

Consider space-saving options like Simpolo’s Savvy and Antea ceramic urinals—sleek, low-maintenance, and suitable for both homes and commercial spaces.

How to Identify Whether Your Toilet Has a P Trap or S Trap

• Outlet into the floor → S Trap
• Outlet into the wall → P Trap

This simple observation helps ensure correct toilet replacement compatibility.

Maintenance Tips for P Trap and S Trap Systems

• Check trap seal periodically in rarely used bathrooms, especially around connected bathware fixtures
• Ensure proper venting to reduce siphoning-related issues
• Avoid corrosive chemical cleaners that may damage joints
• Clean external bends to minimise staining and residue

Consistent care improves hygiene, lifespan, and overall plumbing efficiency.

Troubleshooting Common Issues (S vs P Trap Toilets)

• Gurgling sound or odor → Possible venting or siphon-related concern
• Seal evaporation → More likely in rarely used bathrooms
• Leakage at joints → May indicate loose or worn seal rings

Timely rectification prevents moisture intrusion, staining, and hygiene concerns.

Conclusion

Choosing between an S trap and P trap toilet depends entirely on your bathroom’s existing plumbing. Floor outlets work best with S trap toilets, while wall outlets are ideal for P trap models. There’s no single right answer—just the right fit for your space. At Simpolo Tiles and Bathware, we offer both styles in premium finishes and help you make the best choice. With tools like our 3D Virtual Space Creator and Smart Code previews, planning becomes easier and more accurate. 

Reach out to us for guidance tailored to your bathroom layout.

Related Read: Indian vs Western Toilet: Pros, Cons & Key Differences