Imagine you just moved into a new apartment and noticed a foul smell in your bathroom. You traced the problem to the washbasin and discovered an S trap in the drain pipe. You’re curious about the distinction between an S trap and a P trap and which is better for your plumbing system.
Replacing the S trap with a P trap is one solution to this problem. A P trap has a deeper seal and is less likely to leak, keeping sewer gasses out of your home. This simple fix can improve your home’s overall health and safety.
This article will examine the key differences between S-trap and P-trap drain pipes. By the end of this article, we’ll go over other key differences to better understand which type of drain pipe best suits your plumbing system.
What is S Trap?
Named for its shape, the S trap is most commonly installed in basement toilets or pipes through the floor. For this reason, S traps were in vogue for many years. In modern times, the S trap is old-fashioned.
Once you flush the toilet, this water will first go down, then rise to a certain point and go down again. As soon as it finishes its course, the water from the toilet will form a trap around the first bend.
On the downside, if you want to install this type of trap, you must free up more space in your bathroom. Also, comparing an S trap to a P trap, the former siphons dry more easily
The water level drops when the siphon dries up, and the sewer gas gap opens. Fortunately, if this happens, you can pour a glass of water into the trap and seal it again.
As mentioned, the purpose of adding a trap is to prevent gas and rodents from entering your bathroom. While the water is trapped, the sewer gasses stay in place.
You may have noticed a bad smell in bathrooms that are rarely used because the water in the trap can evaporate. The next thing is that sewer gasses enter your home. So having an S-trap with a vent is ideal.
Pros:
- Simple design: S traps are simple to install and maintain due to their straightforward design.
- Cost-effective: They are less expensive than other types of traps, making them a popular choice for frugal homeowners.
- Ideal for low-flow fixtures: S traps are ideal for low-flow fixtures such as sinks and showers because they provide a sufficient water seal to prevent sewer gasses from entering the room.
Cons:
- Not up to code: S traps are not up to code in many jurisdictions because they can siphon water from the trap, allowing sewer gasses to enter the room.
- Risk of page: Because of their sharp bends, which can trap debris and cause clogs, S traps are more prone to blockages than other traps.
- Not Ideal for high flow fixtures: S traps may not provide a sufficient water seal for high-volume fixtures such as toilets, which require a deeper trap to prevent sewer gasses from entering the room.
Why is S-trap Illegal in New Construction?
S-traps are prone to siphoning, which can result in the loss of the water seal and the entry of sewer gasses into the building.
S-traps are not vented, leading to air pressure issues and impeding proper drainage.
Because of their sharp bends, S-traps are more likely to become clogged with debris because of their sharp bends, resulting in backups and other plumbing issues.
S-traps do not comply with current plumbing codes and standards, which call for using P-traps or other approved traps.
Using S-traps in new construction may lead to code violations, failed inspections, and legal liabilities for contractors and property owners.
What is P Trap?
The P trap, likewise, forms a P-shape. The trap descends, bends, straightens, and finally opens to form a P-shape. This type of trap is usually installed in new kitchens and bathrooms, especially upstairs.
Nowadays, plumbers prefer to use P traps because they are less risky. If you install it correctly, there is no way you will be dealing with a dry siphon. The P trap creates an ultra-strong seal. If you miss a few steps, your P trap will lose its seal and allow harmful gases to enter your home.
It has many applications because the correct P trap configuration is efficient and consistent. Moreover, it does not dry out easily or loosen the seal.
But to take advantage of its beneficial configuration, you must ensure the installation is correct. You can hire a licensed plumber to make sure the installation is correct. So, you won’t have any problem with the toilet.
Pros:
- Meets building codes: P traps meet building codes in most jurisdictions, making them safer and more reliable than S traps.
- Very effective in preventing odor: P traps provide an adequate water seal to prevent sewer gasses from entering the room, making them an effective choice for any fixture in the home.
- Easy to maintain design: Because of their simple design, P traps are simple to clean and maintain.
Cons:
- Takes up more spaces: P traps require more vertical space than S traps, which can be an issue if space beneath the fixture is limited.
- More expensive: P traps are typically more expensive than S traps, making them less appealing for budget-conscious homeowners.
- Not ideal for low-flow fixtures: P traps are not recommended for low-flow fixtures because they require a certain amount of water to maintain the water seal, resulting in dry traps and sewer gas odors.
4 Key Differences between S Trap and P Trap Drain Pipe
Drain pipes are important to any plumbing system because they remove waste water and keep it from backing up into the house. The S and P traps are two drain pipes commonly used in plumbing systems. While they both serve the same purpose, they have some significant differences.
1. Design
S-traps have a sharp bend that creates a water seal to prevent gasses from passing through, but they are prone to siphoning and clogging. P-traps have a deeper, more gradual bend, which creates a better water seal and prevents siphoning.
P-traps are also vented to allow air to flow through, which prevents air pressure issues and improves drainage. P-traps are a more efficient and dependable design for modern plumbing systems.
2. Installation & Location
S-trap and P-trap drain pipe installations are similar, but key differences exist. Because of their simpler design, S-traps are typically easier and faster to install because of their simpler design, but they require a vent to prevent siphoning. P-traps necessitate a deeper trap arm and vent, which takes up more space and requires additional fittings. Still, they provide better protection against sewer gasses and air pressure problems.
S-trap and P-trap drain pipes are typically found beneath sinks, showers, and other plumbing fixtures. Because of their deeper bend, P-traps require more vertical space than S-traps, but they are more effective at preventing sewer gas odors and comply with modern plumbing codes. S-traps are generally only appropriate for low-flow fixtures and are not permitted in many jurisdictions for new construction.
3. Working
The primary difference between S-trap and P-trap drain pipes is their ability to prevent sewer gasses from entering the room. S-traps rely on a water seal created by the sharp bend in the pipe to block gasses, but this design can result in siphoning and dry traps, which can lead to odors and other plumbing problems.
P-traps have a deeper, more gradual bend that creates a larger water seal and prevents siphoning, resulting in more reliable sewer gas protection. P-traps must also have a vent to allow air flow and avoid air pressure issues. Overall, P-traps are more effective and reliable in modern plumbing systems, whereas S-traps are restricted to specific applications and are illegal in many jurisdictions.
4. Black flow prevention
S-trap and P-trap drain pipes are intended to keep wastewater and sewer gasses from entering the room. However, due to their deeper, more gradual bend, which creates a larger water seal, P-traps are more effective at preventing backflow than S-traps. P-traps are typically vented to allow air to flow through and prevent air pressure issues that can lead to backflow.
On the other hand, S-traps are more susceptible to siphoning and dry traps, which can result in backflow and allow sewer gasses into the room. In conclusion, P-traps are a more dependable and effective option for preventing backflow and odors caused by sewer gas.
Finally, S trap and P trap drain pipes serve the same purpose of keeping sewer gasses out of the house. On the other hand, P traps have a deeper seal and are easier to install and maintain than S traps. You should use P-trap drain pipes in your plumbing system when renovating or building a new home.
What is Better for Toilet Bowl S-trap or P-trap?
The P-trap is the better choice for a toilet bowl. P-traps provide a stronger water seal and prevent siphoning, which helps keep sewer gas odors out of the room. Because they tend to siphon and have the potential for dry traps, S-traps are not suitable for toilets. Most building codes and standards also require p-traps for toilet installations.
How to Convert an S-trap to a P-trap?v
To change an S-trap to a P-trap, remove the existing S-trap and replace it with a P-trap. To accommodate the deeper bend of the P-trap, the existing drain pipe may need to be cut and extended. A vent must also be installed in the drain line to prevent air pressure issues and ensure proper drainage. It is recommended that a licensed plumber perform this conversion to ensure that it is done correctly and safely.
What Are Air Admittance Valves (AAVs)?
Air Admittance Valves (AAVs) are one-way mechanical valves that allow air to enter the plumbing system while preventing negative pressure buildup that can cause backflow and other plumbing issues. In areas where venting through the roof is not possible or practical, they are typically used instead of traditional vent pipes. AAVs are installed at the top of the plumbing system and come in various sizes and configurations to fit various plumbing systems.
Should a Kitchen Sink Have an S-trap or P-trap?
A P-trap should be installed in a kitchen sink. P-traps provide a stronger water seal and prevent siphoning, which helps keep sewer gas odors out of the room. S-traps are unsuitable for kitchen sinks due to their increased susceptibility to siphoning and the potential for dry traps. Most building codes and standards also require P-traps for kitchen sink installations.
Conclusion
We hope you have no more doubts about these two types of traps. Regarding S trap vs. P trap toilets, the former is typically considered more convenient due to its effectiveness in blocking sewer gasses that can produce unpleasant odors in your bathroom. The S trap is a typical fixture in floor toilets. However, the good news is that it can be converted into a P trap.
This method is sometimes necessary, such as when the S trap keeps giving you problems. If your S-Trap still seems to be working well, no changes need to be made. However, a strange smell in your kitchen or bathroom may indicate that the trap has failed. You can easily replace your old trap for less, but waiting until the old one breaks is best.
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