What trap to use for a kitchen sink?

Author: Tanya Becker  |  Last update: Wednesday, June 24, 2026

Traps come in 1-1/4 inch (standard bathroom sink) or 1-1/2 inch (standard kitchen sink) inside diameter sizes. Be sure to check so you get the right size replacement at your local store.

Which trap is better for a kitchen sink?

The classic shape of trap is the p-trap. Here, the water seal remains standing in a U-shaped bent pipe under the drain. It is suitable for standard to large wash basins thanks to its excellent “elbow”.

Should I use a S or P-trap for sink?

So if you're considering plumbing s-trap or p-trap, you should go with the p-trap plumbing. If you use s trap plumbing on your kitchen sink or bathroom sink, there is a chance that running water could become siphoned out of the trap, eliminating your trap seal, now you have sewer gases coming into your home.

Do you need an AP trap for a kitchen sink?

The main purpose of the p-trap is to prevent sewer gases from entering the living space. So yes, you need one.

Which trap is used for sinks?

P-traps, named after their shape, contain a u-shaped bend that filters wastewater as it enters a plumbing system. The trap is connected to a sink, bathtub, and shower with a J-bend on one end and exits into your drainage system.

How Do P-Traps Work? | Spec. Sense

What kind of trap do I need for a kitchen sink?

Traps are made from polypropylene (white or black), ABS (black), PVC (white) or brass (either chrome-plated or natural colored). Traps come in 1-1/4 inch (standard bathroom sink) or 1-1/2 inch (standard kitchen sink) inside diameter sizes. Be sure to check so you get the right size replacement at your local store.

Is a bottle trap better than an AP trap?

Is A Bottle Trap Better Than A P Trap? Every trap has arguments for why it is the best, but overall, yes Bottle Traps are the most convenient. A Bottle Trap takes up considerably less space than the alternative P-Traps and S-Traps, however Bottle Traps and S-Traps fulfill different needs.

Should a kitchen sink have 2 P-traps?

Plumbing codes expressly prohibit the use of double traps.

Which is best, P-trap or s-trap?

P-traps, with their additional horizontal arm, are designed to maintain this water seal effectively. Reducing Drying Out: P-traps also reduce the risk of drying out. In S-traps, the water in the trap can evaporate more quickly due to their shape and exposure, leading to the same issue of gas leakage.

What can I use instead of a P-trap?

Waterless traps

Wavin Osma's HepvO waterless trap provides a hygienic alternative to the traditional trap because it cannot dry out. Its self-sealing membrane provides permanent, watertight protection.

Why is s-trap illegal?

The “S” trap is prohibited under the Uniform Plumbing Code throughout the United States. This is because the “S” trap will siphon or suck water out from the trap which will end up releasing methane (sewer) gases into the home. So, it is a code violation and if you are doing remodeling, you will have to replace it.

What size of P trap is required for a kitchen sink?

For instance, bathroom sink P-traps are typically 1 ¼ inches in diameter, while those for kitchen sinks are typically 1 ½ inches. P-traps work by utilizing a water seal in their curve to block sewer gases from entering your home while simultaneously allowing wastewater to pass.

Why is an AP trap better than an S trap?

In contrast to S-traps, P-traps feature a distinct "P" shape, with a horizontal pipe connected to a vertical pipe that leads into the drainage system. P-traps are widely used in modern plumbing installations due to their effectiveness in preventing sewer gas leaks and their versatility in various applications.

Should I use S or P-trap for sink?

While S-traps may still be found in older properties, upgrading to P-traps ensures compliance with modern standards and reduces the risk of sewer gas intrusion. Regular maintenance and professional consultations are key to keeping your bathroom plumbing in optimal condition.

Which trap is used in kitchen?

P-Trap: They are more commonly used in exposed plumbing systems, such as under bathroom sinks or kitchen sinks, where the plumbing is visible.

Why are bottle traps illegal?

Bottle traps don't allow a mechanical device to pass through, so they don't meet that aspect of the code, either. Finally, traps need to be self-scouring, meaning that they clean themselves as water passes through. Again, bottle traps don't meet this particular requirement either.

Why not use an S trap?

Answer: The biggest risk of an S trap is siphoning, which can cause the trap to lose its water seal. This allows dangerous sewer gases to enter your home, creating potential health risks and unpleasant odors.

Which trap is better for kitchen sink?

P traps are very popular options as they're reliable and cost effective. The way they work is that the small bend in the pipe traps the water which creates a 'plug'. As water drains through the trap, air is pulled from an external vent which helps to equalise the pressure.

When were S traps banned in the USA?

Code Compliance

S traps are prohibited throughout the United States by the International Plumbing Code. They have been banned since 2006 because of the siphonage hazard. It could cause the water seal to escape the conduit.

Does a kitchen sink have an S or p-trap?

We can use a trap to catch any water or other fluids not meant to be in the basin or the drain. P-traps are typically used in kitchens as they can handle cold water. In contrast, S-traps are more suited for bathrooms because they can only handle warm water.

Why is double trapping a problem?

While installing two traps in series might appear to be a good safety measure, this practice is not recommended because it can lead to trap blockage and waterlogging of all equipment trying to drain into it, similar to when a trap is completely blocked.

What is the minimum size of trap suitable for use with a kitchen sink?

Because of its shape, a trap retains a small amount of water after the fixtures use. This water creates an air seal which helps stop smells making their way from the drain back into your house. Wash hand basin (bathroom sink) wastes use a 32mm / 1-1/4 inch trap. Kitchen sinks and baths use a 40mm / 1-1/2 inch trap.

What are the disadvantages of P-traps?

Disadvantages of P-Traps

One common issue is that the water seal can be protected if properly maintained or if there are blockages in the drainpipe. This can lead to the escape of sewer gases and unpleasant odors. The trap is regularly inspected and cleaned to ensure its proper functioning.

What is the most commonly used trap?

The P-trap is the most common house plumbing trap. Its U-shaped design holds water and is installed beneath sinks in both bathrooms and kitchens.

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