What is a curb trap?

Author: Mr. Buck Mante  |  Last update: Friday, January 23, 2026

The curb trap is a part of the piping line in your sewage system that prevents water from escaping into your home. The curb trap also keeps sewer gas from getting into the main drain and the house. It is a U-shaped pipe that is connected to a vent that circulates fresh air through the sewage system.

What is the purpose of a curb trap?

Main House Drain (I): Piping that collects the waste and empties to the lateral. Curb Trap (H): Portion of pipe that traps sewer gases from entering property.

What is the difference between a house trap and a cleanout?

Superior Materials– Whereas house traps corrode over time, cleanouts can be made with superior, PEX pipe materials that are immune to rust, erosion, and sediment build-up.

Why is an S-trap illegal?

S traps are illegal because they Can siphon. That does not mean they siphon 100% of the time. If you are doing work on your own house, it'll be fine. If you are doing work, professionally, for the public, you should do it correctly and to code.

What is the purpose of a curb drain?

Curb inlets are crucial for effective stormwater management, directing water from roadways into the drainage system to prevent flooding and erosion. They help maintain road safety and longevity by efficiently managing water runoff.

Curb trap

What is the purpose of a curb?

A curb serves one or more of the following purposes: drainage control; access control; pavement edge delineation and support; right-of-way reduction; aesthetics; delineation of pedestrian walkways; protection of pedestrians, signs, trees and grass; reduction of maintenance operations by preventing water seepage under ...

How to divert water runoff away from a house?

This can be done using swales, French drains, catch basins or downspout and sump pump extensions. These methods of rerouting can be combined together with capture and storage practices (see below). Whenever you are redirecting runoff, you must send it to a suitable outlet.

Does an S-trap meet code?

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.

Is a P-trap or S-trap better for a bathroom sink?

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.

What traps are prohibited in plumbing?

Full “S” traps, bell traps, drum traps, crown-vented traps, and running traps are prohibited. Fixtures shall not be double- trapped.

Are house traps obsolete?

Essentially, water gets caught in the curved pipe and blocks gasses from drifting back through the system. In other words, the “trap” part of the term is literal: sewer odors become “trapped” in your plumbing system and can't invade your living spaces. Nowadays, house traps are 100% obsolete.

Does every drain need a trap?

P-traps are named as such because the bend and leg on the trap somewhat resemble the letter P turned on its side. The Uniform Plumbing Code states that P-traps are required for every drain line that carries wastewater into the plumbing vent-waste drain system.

What is a gully trap?

A Gully Trap is a drainage pipe extension in the form of a basin that allows waste water to safely enter the sewage system with a seal that traps dangerous gases and prevents the gases from escaping.

Does every house have a sewer trap?

A house trap, also referred to as a building trap or sewer trap, is a plumbing feature that was fairly standard in older homes but is generally considered outdated now. The house trap is a curved pipe of the sewer line that holds a small amount of water at all times.

Who is responsible for the water line from street to house?

Who is Responsible for the Water Line From the Street to Your House? Water service lines within the bounds of your property are considered your personal responsibility to maintain, while public water pipes outside of private property lines are the city's responsibility.

What is a curb stop in plumbing?

The curb stop is defined as a valve installed in the water service line and accessible for operation from aboveground for routinely interrupting flow through the service line. The curb stop is located below ground, directly beneath the curb box, which is typically between the water main and building structure.

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.

Why not use S-trap?

The “s” design could cause a water siphon, removing the water built up in the curve, opening the seal, and allowing sewer gas to pass through. This flaw is whys-traps are no longer allowed in plumbing code and should be replaced if you have one.

What are the disadvantages of S traps?

S-traps were once a common sight in older plumbing systems, but they have fallen out of favour due to their tendency to siphon water out of the trap, leading to sewer gas leaks and drainage issues.

Are p-traps illegal?

For this reason, S-traps was officially banned under the Uniform Plumbing Code, and P-traps became the new standard. The shape of the P-trap is just one feature that helps stop this from happening.

Why is an AP trap better than an S-trap?

The P-trap is now the standard since the S-trap was deemed ineffective and prohibited in new construction under the Universal Plumbing Code. The S-trap was found to be prone to siphoning and drying out, which leaves the apparatus ineffective.

Do rocks help keep water away from foundation?

One way to ensure that water drains away from your home is by landscaping in a strategic manner. By utilizing rocks for drainage, you can keep water away from your foundation and your home.

How do I divert water away from my house without gutters?

For those without gutters, consider artistic solutions like rain chains. These decorative chains attach to your roof and channel rainwater down each link, creating a visually appealing water feature while effectively directing the flow away from your house.

What is a French drain around a house?

A French drain is a trench filled with a perforated pipe and gravel that allows water to drain naturally from your yard. Depending on the size of your yard and the scale of your drainage issue, you can purchase the pipes and equipment to create a French drain yourself.

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