The vertical distance from the fixture outlet to the trap weir shall not exceed 24 inches (610 mm), and the horizontal distance shall not exceed 30 inches (610 mm) measured from the centerline of the fixture outlet to the centerline of the inlet of the trap.
Each plumbing fixture shall be separately trapped by a water seal trap placed as close as possible to the fixture outlet, but not more than 2 ft. horizontal developed length from the outlet of the fixture. The vertical distance from the fixture outlet to the trap weir shall not exceed 48 in.
For a 1 ½-inc pipe the vent should be 42 inches away at the most while a 2-inch pipe must have a maximum distance of 5 feet. For pipes that have a diameter of 3 inches the distance is 6 feet and for a 4-inch pipe the most it should be away from the vent is 10 feet.
Each “P” trap shall have a water seal of not less than 2 inches and not more than 4 inches and shall be set true to its seal. (6) Size. Traps shall be not less than 1 1/4 inches in diameter. A trap shall not be larger than the waste pipe to which it is connected.
Every single fixture in a plumbing system has some sort of P-trap. And even though there's a certain artistry to its curvy shape, it's not just an adornment. It performs a special function for the fixture it's connected to or 'serving'.
The Uniform Plumbing Code states that P-traps are required for every drain line that carries wastewater into the plumbing vent-waste drain system. This means that every sink, shower and floor drain should have a P-trap that connects the drain to the drain line.
The S-Trap's Major Flaw
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.
The primary purpose of the horizontal distance of 30 inches (762 mm) from a fixture outlet to the trap weir is to limit the amount of bacterial growth and resulting odor. It is desirable to locate the trap as close as possible to the fixture.
The trap code is a quantum message authentication code first introduced in the context of quantum one-time programs [BGS12]. Its security is further explored in [BW16].
The typical rule of thumb according to code requires you to run a horizontal pipe for no more than one-third of the total length.
Can my toilet and sink share the same vent? Yes, the toilet and sink can share the same vent, as can the shower.
P-traps are known for their reliability and efficiency in maintaining a water seal, which helps to prevent sewer gases from entering buildings. Additionally, P-traps are less prone to syphoning and drainage issues compared to S-traps, making them a preferred choice for both residential and commercial plumbing systems.
P109. 8 Fixture Vents
The vent pipe opening from a soil or waste pipe, except for water closets and similar fixtures, shall not be below the weir of the trap. No vent shall be installed within two pipe diameters of the trap weir.
It's shaped like a “P” and can be found under sinks, tubs and showers. A simple device, a P-trap holds just enough water to create an airtight seal that prevents sewer gas from backing up into your home. As you run water down a drain, you're continuously refilling that trap.
Common trapped fixture outlets shall be not more than 30 inches (762 mm) apart.
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.
A "Crown Vent" is a vent that is located within 2 pipe diameters of the trap it is serving. The issue is if the vent is that close it is more likely to be subjected to fouling of hair, soap oils, grease, and other debris.
Rules and Regulations to Know Regarding Shower Traps
As we previously mentioned, it is a law in the United States that every shower has a P-trap. In addition to this rule, P-traps must be no more than 5 feet away from the shower drain. Ideally, it should be as close to your shower inlet as possible.
In all of these cases, water has to pass through two separate traps, called a double trap. But don't confuse this with two separate traps, which is fine. Of course, those corrugated things in the photo above aren't proper, but the configuration is correct. Plumbing codes expressly prohibit the use of double traps.
The following types of traps are prohibited: Bell traps. Separate fixture traps with interior partitions, except those lavatory traps made of plastic, stainless steel or other corrosion-resistant material. "S" traps.
Pros of Toilet P-Traps
The additional vent pipe most P-trap toilets require further lower the risk of gas siphoning. Most modern plumbing codes require P-trap toilets for residential installations.
Plumbing systems in the United States and most parts of Canada typically have P-traps, as these parts are required by law. In other parts of the world, this requirement varies. You can check by inserting a snake into the shower's drain.