P Trap vs. S Trap — What's the Difference?
By Tayyaba Rehman — Published on November 21, 2023
P Trap is a U-shaped pipe designed to trap debris from drains, with its outlet at the back. S Trap has a similar function but its outlet is at the bottom.
Difference Between P Trap and S Trap
Table of Contents
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Key Differences
P Trap and S Trap are both essential plumbing components used to prevent foul odors and gases from entering homes and buildings. While they serve a common purpose, their designs and applications differ considerably.
The P Trap, resembling the shape of the letter 'P', has its bend and outlet oriented towards the back, typically aligning with the wall. It's commonly found under sinks, ensuring that wastewater flows efficiently while trapping debris and forming a seal against sewer gases. Since the P Trap's outlet is towards the back, it's suited for installations where the waste pipe enters the wall.
Conversely, the S Trap, mirroring the letter 'S', positions its bend and outlet downwards. This design is more appropriate when the waste pipe is located in the floor rather than the wall. Although the S Trap effectively keeps out unwanted odors and gases, it's less common in modern plumbing due to potential siphonage issues which can break the water seal, defeating its primary purpose.
The decision between using a P Trap and S Trap primarily rests on the waste pipe's position and local plumbing codes. It's imperative for individuals to consult with professionals or familiarize themselves with regional requirements before making a selection.
Comparison Chart
Shape
Resembles the letter 'P'
Resembles the letter 'S'
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Outlet Position
At the back
At the bottom
Common Installation
Under sinks with wall waste pipe
For floor waste pipe entries
Risk of Siphonage
Lower
Higher, can lose water seal
Modern Usage
More common in modern plumbing
Less common due to siphonage concerns
Compare with Definitions
P Trap
P Trap is a U-shaped plumbing fixture that prevents sewer gases from entering buildings.
Installing a P Trap under the kitchen sink ensured no foul odors seeped into the house.
S Trap
S Trap's distinct shape has its outlet positioned downwards, suitable for floor entries.
Since our drainpipe was in the floor, we used an S Trap for the shower.
P Trap
P Trap installations are common in contemporary plumbing systems.
During the home inspection, they checked the condition of the P Trap under our bathroom sink.
S Trap
Though effective, S Traps are less favored in modern plumbing due to certain challenges.
Our plumbing consultant advised against using an S Trap for the new bathroom layout.
P Trap
P Trap creates a water seal, blocking unwanted gases and trapping debris.
I was relieved when the P Trap caught my fallen ring before it disappeared down the drain.
S Trap
S Trap's design resembles the letter 'S', with curves facilitating its function.
The S Trap under our bathtub needed replacement after years of service.
P Trap
P Trap is often made of PVC, metal, or other durable materials.
We chose a stainless steel P Trap for its longevity and aesthetics.
S Trap
S Trap is an essential plumbing device, designed to prevent foul odors from entering via drains.
Our old house had an S Trap installed due to the floor-based waste pipe.
P Trap
P Trap has its outlet oriented towards the back, aligning with wall entries.
The plumber recommended a P Trap since our waste pipe entered the wall.
S Trap
S Trap can risk siphonage, potentially compromising its water seal.
We replaced the S Trap with a P Trap to reduce the chances of siphonage.
Common Curiosities
Why might someone choose a P Trap over an S Trap?
A P Trap is often chosen for wall waste pipe entries, and it poses a lower risk of siphonage compared to the S Trap.
Are S Traps banned in some places?
Yes, some building codes have banned or discouraged S Traps due to the risk of siphonage.
What is the primary function of both P Trap and S Trap?
Both P Trap and S Trap work to prevent sewer gases from entering buildings while allowing water to drain.
Can these traps catch debris or items accidentally dropped down the drain?
Yes, both P Trap and S Trap can catch debris or items like rings that might accidentally fall into the sink.
How do P Trap and S Trap form a barrier against sewer gases?
Both traps hold water, creating a seal that stops sewer gases from rising up through the drain.
Can an S Trap be converted into a P Trap?
Yes, with proper plumbing adjustments, an S Trap can be converted to a P Trap.
How does the design of P Trap and S Trap differ?
P Trap resembles the letter 'P' with a back outlet, while S Trap mirrors 'S' with a bottom outlet.
Are there other trap designs besides P Trap and S Trap?
Yes, there are other designs like bottle traps and drum traps, but P and S are the most common.
Which trap is more common in modern homes?
P Trap is more commonly used in modern homes due to fewer siphonage issues and wall-oriented plumbing.
How often should I clean or check my P Trap or S Trap?
Regularly, especially if you notice slow drainage or detect foul odors.
What materials are P Traps and S Traps typically made of?
They are made from materials like PVC, metal, or brass.
How do I determine if I have a P Trap or S Trap installed?
Look at the shape and outlet position; P Traps direct towards the back, while S Traps point downwards.
Why is siphonage a concern with S Traps?
Siphonage can cause the water seal in an S Trap to be sucked out, allowing sewer gases to enter.
Can I install a P Trap or S Trap by myself?
While possible, it's recommended to consult or hire a plumber for proper installation.
Is there a significant cost difference between P Trap and S Trap?
Typically, the cost difference is minimal, but the choice often depends on plumbing requirements rather than price.
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Written by
Tayyaba RehmanTayyaba Rehman is a distinguished writer, currently serving as a primary contributor to askdifference.com. As a researcher in semantics and etymology, Tayyaba's passion for the complexity of languages and their distinctions has found a perfect home on the platform. Tayyaba delves into the intricacies of language, distinguishing between commonly confused words and phrases, thereby providing clarity for readers worldwide.
