How To Convert An S-Trap To A P-Trap – A Step-By-Step Guide

If you’re dealing with an S-trap under your sink, you may be experiencing some unpleasant odors and drainage issues.

The good news is that converting it to a P-trap is a fairly simple process that can improve the overall function of your plumbing system.

In this article, we’ll walk you through the steps to convert an S-trap to a P-trap, including what tools and materials you’ll need and some common pitfalls to avoid.

So let’s get started!

How To Convert S-trap To P-trap

Step 1: Assess the Situation

Before you begin, it’s important to determine whether you actually have an S-trap or a P-trap. An S-trap is shaped like an “S” and has a bendy straw-like piece attached to it, while a P-trap is shaped like a “P” and has a horizontal section that connects to the drain pipe.

If you do have an S-trap, it’s important to convert it to a P-trap to prevent sewer gases from entering your home and causing unpleasant odors.

Step 2: Gather Your Materials

To convert your S-trap to a P-trap, you’ll need the following materials:

– PVC piping

– PVC glue

– P-trap assembly

– Air admittance valve (optional)

You may also need additional materials such as compression fittings or a T offset if your existing piping doesn’t line up with the new P-trap assembly.

Step 3: Remove the Existing S-Trap

Using a wrench or pliers, carefully remove the existing S-trap from under your sink. Be sure to turn off the water supply before you begin.

Step 4: Install the New P-Trap Assembly

Attach the new P-trap assembly to the drain tail pipe under your sink. Make sure it’s securely fastened and properly aligned with the drain pipe.

Step 5: Add an Air Admittance Valve (Optional)

If your plumbing system doesn’t have a vent stack, you may need to add an air admittance valve to prevent siphoning and allow proper drainage. This valve should be installed at least 4 inches higher than the horizontal section of the trap.

Step 6: Test Your Plumbing System

Once you’ve installed the new P-trap assembly and any necessary components, turn on the water supply and test your plumbing system for leaks or drainage issues. If everything is working properly, congratulations! You’ve successfully converted your S-trap to a P-trap.

Understanding The Difference Between S-trap And P-trap

The main difference between S-traps and P-traps lies in their shape and design. An S-trap curves up and then down from the drain, while a P-trap curves down and then finishes with a horizontal pipe that connects to the drain. The main issue with S-traps is that they tend to siphon away too much waste water, leaving the drain “dry”. This dry trap allows unwanted gases to enter the home, including odorless and dangerous gases like carbon monoxide. On the other hand, a P-trap is designed to prevent this issue by creating a water barrier that keeps all gases from entering the home.

While both types of traps serve the same purpose, P-traps are generally considered more reliable and effective than S-traps. This is because P-traps have a vent and drain line that prevent siphoning and allow proper drainage. Additionally, P-traps are less likely to dry out and let undesirable odors reach your bathroom by losing their water seal.

If you currently have an S-trap installed in your home and frequently smell sewer gases, it’s important to consult with a plumbing team about switching to a P-trap. Converting an S-trap to a P-trap involves installing a vent pipe within an air admittance valve (AAV) and a waste arm extension that connects the trap to the vent pipe and drain line. This conversion process requires some plumbing knowledge and expertise, so it’s recommended to hire licensed plumbers with considerable experience for this task.

Tools And Materials Needed For Converting S-trap To P-trap

To convert an S-trap to a P-trap, you’ll need a few tools and materials. Here are the things you’ll need:

1. PVC piping: You’ll need PVC piping to create the new drain setup. Make sure you have enough piping to create the new P-trap assembly.

2. PVC glue: You’ll need PVC glue to connect the new piping together. Make sure you have enough glue to properly secure all of the pieces.

3. P-trap assembly: You’ll need a P-trap assembly to replace the existing S-trap. Make sure the assembly fits properly with your existing plumbing.

4. Air admittance valve (optional): If your plumbing system doesn’t have a vent stack, you may need to install an air admittance valve. This valve will prevent siphoning and allow proper drainage.

5. Compression fittings or T offset (optional): Depending on your existing plumbing setup, you may need additional fittings such as compression fittings or a T offset to properly align the new P-trap assembly with your drain pipe.

Make sure you have all of these tools and materials before beginning the conversion process. It’s important to have everything on hand to ensure a smooth and successful conversion from an S-trap to a P-trap.

Step-by-Step Guide To Converting S-trap To P-trap

Step 1: Identify the Problem

If you’re experiencing unpleasant odors coming from your sink, it’s likely that you have an S-trap that needs to be converted to a P-trap. An S-trap can siphon and allow sewer gases to enter your home, causing the odor.

Step 2: Turn Off the Water Supply

Before you begin any plumbing work, it’s important to turn off the water supply to your sink. This will prevent any accidental leaks or water damage.

Step 3: Remove the Existing S-Trap

Using a wrench or pliers, carefully remove the existing S-trap from under your sink. Be sure to loosen all connecting nuts and remove any additional piping that may be attached.

Step 4: Measure and Cut PVC Piping

Measure the distance between the drain tail pipe and the floor drain. Cut a length of PVC piping to fit this distance, making sure to account for any necessary bends or offsets.

Step 5: Install the P-Trap Assembly

Attach the new P-trap assembly to the drain tail pipe under your sink. Make sure it’s securely fastened and properly aligned with the drain pipe. Use PVC glue to ensure a tight seal.

Step 6: Connect PVC Piping

Attach one end of the PVC piping to the bottom of the P-trap assembly and the other end to the floor drain. Use compression fittings or a T offset if necessary to ensure proper alignment.

Step 7: Add an Air Admittance Valve (Optional)

If your plumbing system doesn’t have a vent stack, you may need to add an air admittance valve to prevent siphoning and allow proper drainage. This valve should be installed at least 4 inches higher than the horizontal section of the trap.

Step 8: Test Your Plumbing System

Once you’ve installed the new P-trap assembly and any necessary components, turn on the water supply and test your plumbing system for leaks or drainage issues. If everything is working properly, congratulations! You’ve successfully converted your S-trap to a P-trap.

Benefits Of Converting S-trap To P-trap

There are several benefits to converting an S-trap to a P-trap. Firstly, P-traps are more effective at preventing sewer gases from entering your home. The addition of a vented pipe and waste arm extension significantly reduces the likelihood of siphoning, which can cause the trap to dry out and allow gases to enter your home. This means that your home will be safer and more pleasant to live in.

Secondly, P-traps are more efficient at catching objects that fall down the drain. The extended pipe on the drain side of the trap reduces the possibility of gravity “pulling” water through the pipe, which means that objects are less likely to get stuck in the trap. This can save you time and money on costly repairs.

Finally, converting an S-trap to a P-trap is often required by local building codes. Most jurisdictions banned the use of S-traps in new plumbing installations several decades ago, so if you have an S-trap in your home, you may be required to replace it with a P-trap. By converting your S-trap to a P-trap, you’ll ensure that your plumbing system complies with local regulations and avoid any potential legal issues in the future.

Conclusion And Final Thoughts

In conclusion, converting an S-trap to a P-trap is an important step in ensuring the proper functioning of your plumbing system and preventing unpleasant odors from entering your home. While it may seem like a daunting task, with the right materials and tools, it can be done relatively easily. It’s important to remember that plumbing codes vary by jurisdiction, so be sure to research the regulations in your area before beginning any plumbing work. Additionally, if you’re not confident in your ability to complete the conversion yourself, it’s always best to hire a licensed plumber to ensure the job is done correctly. By following these steps and taking the necessary precautions, you can enjoy a properly functioning and odor-free plumbing system in your home.