If you’ve ever peeked under your sink and wondered what kind of plumbing setup you’re looking at, you’re not alone. At True Blue Plumbing in Snellville, GA, homeowners often ask us about the difference between an S trap vs P trap. These two types of drain traps may look similar, but they function differently—and knowing which one you have can help you avoid plumbing problems down the road.
What Is a Plumbing Trap?
Before diving into the differences between an S trap and a P trap, it’s important to understand what a plumbing trap is. A trap is a curved pipe beneath your sink or fixture designed to hold a small amount of water. This water acts as a barrier, preventing unpleasant sewer gases from backing up into your home. Every drain in your house—whether it’s for a sink, shower, or tub—should be connected to a trap.
S Trap vs P Trap: How They’re Shaped
One of the easiest ways to tell the difference between an S trap vs P trap is by looking at their shape.
An S trap curves in a continuous “S” shape, with the pipe dropping vertically into the floor. In contrast, a P trap has a horizontal outlet and resembles a sideways “P,” connecting into the wall instead of the floor. This distinction isn’t just cosmetic—it’s critical to how the trap performs and whether it complies with modern plumbing codes.
Why P Traps Are Code-Compliant (and S Traps Aren’t)
In modern plumbing systems, P traps are the standard. That’s because they are vented properly through the wall, allowing air to flow and maintaining consistent water levels in the trap. This reduces the risk of the trap drying out or siphoning itself empty after water flows through it.
On the other hand, S traps are no longer allowed under most building codes, including in Georgia. The reason is simple: they’re prone to siphoning. When water flows rapidly through an S trap, it can create a vacuum effect that pulls all the water out of the trap. Once that happens, sewer gases can enter your home, leading to foul smells and even potential health risks.
Common Issues with S Traps in Older Homes
Although no longer permitted in new construction, S traps are still commonly found in older homes throughout Snellville and the surrounding areas. If you live in a house built before the 1980s, you might still have one under your sink.
Problems caused by S traps include:
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Gurgling sounds when water drains
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Sewer odors coming from the drain
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Slow drainage or frequent clogs
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Inconsistent water levels in the trap
If you’re experiencing any of these issues, it may be time to upgrade from an S trap to a P trap.
Converting an S Trap to a P Trap
Replacing an S trap with a P trap isn’t always as simple as swapping out the pipe. Because P traps connect to a horizontal drain line in the wall, your plumbing system may need to be reconfigured. This often involves rerouting the drain pipe and adding a proper vent connection to meet code requirements.
At True Blue Plumbing, we specialize in retrofitting outdated plumbing systems with modern solutions. We’ll evaluate your current setup, recommend the most efficient upgrade, and ensure all work meets local plumbing codes in Snellville and Gwinnett County.
S Trap vs P Trap: Which Is Better for DIY?
While P traps are easier to find and install for modern plumbing, S traps sometimes tempt DIYers because they seem simpler to install—especially when the drain pipe leads into the floor. However, choosing an S trap can cause more trouble than it’s worth. Besides being against code, an S trap is more likely to cause odor problems, drainage issues, and long-term maintenance headaches.
If you’re working on a bathroom or kitchen renovation, it’s always best to consult a licensed plumber to ensure your drain system is safe, effective, and code-compliant.
How to Identify Which Trap You Have
Still unsure if you’re dealing with an S trap or P trap? Here’s how to quickly spot the difference:
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S Trap: The pipe loops down and then continues straight into the floor.
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P Trap: The pipe loops and then runs horizontally into the wall.
You can also check where the drain pipe leads. If it disappears into the wall, you likely have a P trap. If it disappears straight down into the floor, it’s probably an S trap.
Local Plumbing Codes and Safety
According to the Georgia State Minimum Standard Plumbing Code (based on the International Plumbing Code), all traps must be properly vented. The use of S traps is specifically prohibited. That’s why replacing an S trap with a P trap isn’t just a good idea—it’s required for safety and code compliance. You can view Georgia’s plumbing codes here.
If you’re not sure whether your home is up to code, our team at True Blue Plumbing can perform a full plumbing inspection and provide clear recommendations.
Trust True Blue Plumbing for Expert Trap Replacement
Whether you’re renovating your kitchen or simply want to get rid of that musty smell coming from your drain, replacing an outdated S trap with a code-compliant P trap is a smart move. At True Blue Plumbing, we serve Snellville and nearby areas with professional plumbing services you can count on.
Our licensed technicians have years of experience in diagnosing and upgrading all types of residential plumbing systems. We use high-quality materials, stay current on code requirements, and take pride in leaving your home cleaner than we found it. Contact True Blue Plumbing in Snellville, GA today for fast, honest, and professional service.
