P-trap vs. S-trap: Understanding the Differences

What are traps in plumbing?

First, let's understand what a trap is in plumbing. A trap is a curved section of a pipe that is designed to prevent sewer gases from entering your home. It does this by holding a small amount of water at all times, which acts as a barrier against the gases. This water barrier is crucial for maintaining a healthy and odor-free environment in your home.

P-Traps: The modern standard

A P-trap is one of the most common types of traps used in modern plumbing systems. Named for its distinctive shape, which resembles the letter "P," a P-trap consists of a curved pipe that creates a water seal to block sewer gases. Here's how the P-trap works:

• Water Seal: The bend in the P-trap holds a small amount of water. This water forms a seal that prevents sewer gases from escaping into your home.
• Cleaning Access: P-traps are often equipped with a cleanout plug at the bottom. This allows you to easily remove clogs and debris without having to dismantle the entire trap.
• Ventilation: P-traps are designed to be connected to a venting system, which helps to equalize pressure and ensure proper drainage.

Benefits of P-traps

The water seal in a P-trap is very effective at blocking sewer gases, keeping your home smelling fresh. P-traps are widely used in contemporary plumbing systems and are compliant with most building codes. They can be used for sinks, showers, and other fixtures, making them a versatile choice for various plumbing needs.

S-Traps: The legacy model

S-traps are also named for their shape, which looks like the letter "S." Similar to P-traps, S-traps hold water in their curved section to prevent sewer gases from escaping. While they serve the same basic purpose as P-traps – creating a water seal to block sewer gases – they have some distinct differences.

For example, a significant drawback of S-traps is that they can sometimes siphon themselves dry. When a large volume of water flows through, it can create a suction effect that pulls the water out of the trap, breaking the seal and allowing gases to escape. Moreover, S-traps are not typically connected to a venting system, which can exacerbate the self-siphoning problem and lead to poor drainage.

Drawbacks of S-traps

S-traps are more commonly found in older homes, so you might run into them if you're repiping or dealing with an older plumbing system. In many areas, S-traps do not meet modern plumbing codes because of their tendency to siphon dry and lack proper venting. The self-siphoning issue can make S-traps less reliable in preventing sewer gases from entering your home, potentially leading to unpleasant odors and health hazards.

Consult with a trained plumber

Are you considering whether to arrange a pipe replacement or repair? If your plumbing pipes are making unusual noises, leaking, or producing foul odors, then call Acknowledge Plumbing to consult with a member of our team.

Our plumbers have you covered with everything from a leak detection to pipe repairs and replacements. Contact Acknowledge Plumbing to get in touch today.