Does P trap have to be below drain?
It is not ideal to have the p-trap below the the exit drain because water gravity has to force the water out instead of it flowing downwards naturally. They both work and have seen it many times. But essentially anything below already creates its own p-trap- so using another is redundant.
According to the International Residential Code, the maximum vertical distance between the sink drain and the entrance to the p-trap is 24 inches.
You must install a trap level in relation to its trap seal. If the trap isn?t level, it can be susceptible to back-siphonage. Check out the diagram in Figure #2. Having said that, any plumbing fixture directly connected to the sanitary drainage system must be equipped with a water seal trap.
No a P trap works in gravity with a constantly downward flow. Gravity drains dont work uphill unless you pump the fluid. The P trap is to keep sewer fumes (can be fatal) from ventung into your home.
A P-trap that is too high is less dangerous but still not advisable. If your P-trap is too low, the water in it is more likely to evaporate, allowing sewer gas to flow up the line. UPC code mandates P-trap height must be 6–18 inches above floor level.
When the trap is too deep, liquid may flow through it too fast, which can lead to siphoning of the trap seal and sludge buildup. The drain connection at the wall is too high on this sink, resulting in a 9-inch-deep trap seal — 5 inches deeper than is allowed by code.
The ZB36000DB Shallow P Trap 19mm, 32mm Seal is available online, from our following retail partners.
Each fixture trap shall have a liquid seal of not less than 2 inches (51 mm) and not more than 4 inches (102 mm), or deeper for special designs relating to accessible fixtures. Trap seals of emergency floor drain traps and trap seals subject to evaporation shall be protected by one of the methods in Sections 1002.4.
They are designed to constantly hold water in the drain to prevent sewer gas from escaping into the house. While sewer gases may contain noxious odors and smell terrible, they can also be explosive and poisonous. Ensuring that your P-trap has enough water will keep things running smoothly.
Location of the P-trap
The International Residential Code, under the International Code Council, says that the P-trap must hang at a maximum height of 24 inches below the drain.
Can you have a 90 before P-trap?
(c) the trap arm does not have a cumulative change in direction of more than 135°. 90+90 = 180°, so that's too much.
If the tailpiece will not line up with the trap, move the trap into its original position, tighten the collar with the pipe wrench and obtain a flexible tailpiece extension for your drain. The size is typically 1 1/4-inch in the outer diameter of the plastic pipe.

Cleanouts absolutely have to be accessible. In fact, if they aren't, you have to extend them to where they are accessible. But a lot of traps are sealed up in walls or floors/ceilings after inspection, particularly for things like washing machines, tubs and toilets. Plumbing snakes will bend and go through the traps.
The simple answer is if your trap from the fixture cannot see the vent then it is installed wrong. We must always keep the vent connection above the trap weir to prevent siphoning and keep proper pressures on both side of the trap.
The standard kitchen sink is 8 inches deep, which means that the normal distance between a kitchen sink drain and the floor is 28 inches. This will vary, depending on the height of the counter and the depth of the sink bowl. In the bathroom, the sink drain is typically between 24 inches above the floor.
There is no minimum distance specified by the building code, but the maximum is 24” per International Residential Code (IRC) and Residential Edition of Florida Building Code (FBC 1002.1), measured from fixture outlet to trap weir.
P-traps need vents
1 – They give the sewer gases a place to vent, so they do not build pressure inside your sewer lines.
The drain into the wall needs to be below that of the disposal and sink, there's no way to beat gravity with this. Your options are to: Raise the disposal output (with a different disposal) Raise the sink (with a different, shallower sink, or at least a shallow drain for the disposal)
Does a P trap have to be straight? The two main parts of a P-trap do not need to be in the same vertical plane. As noted by others, they can be rotated well out of plane to each other when fitted, and commonly are. The horizontal part, its wall tube, should go straight into the house drain system wall pipe.
If you look at the drain pipe under your sink, you'll see a curve in the pipe that resembles the shape of a “U” or a “P.” That's an example of a P-trap. A P-trap is a bend in a drain and waste pipe with a specific purpose.
Why does my P-trap keep clogging?
Rings, earrings, chunks of soap, and even grease can form clogs in your P-trap. If your P-trap is not draining , you may hear a strange stuttering noise when water flushes down the drain. You can manually remove most p-traps from under the sink pretty easily.
Reasons why a P-trap loses water
Oscillation occurs when too much outside air enters the pipe, displacing the water out of the bowl. When something is stuck inside the pipe and absorbs water from the toilet, a P-trap can empty due to capillary action.
The Aquaflow lowback P trap is an essential piece of kit if you're laying underground drainage for soil and wastewater. Its 'P' shape traps foul odours and gases, stopping them from escaping into the atmosphere. Use it with the 110 ml square hopper. This sturdy unit is made from high-quality, maintenance-free plastic.
The minimum trap arm length is two pipe diameters, as measured from the trap weir to the vent (not between the hubs of the fittings). So a 1-1/2” pipe would require a 3” minimum trap arm, and a 2” pipe needs a 4” minimum trap arm.
The curved section of the P trap gully – which makes the gully look a little like a P – creates a space that traps water in the pipe. This forms a barrier that prevents smells and gases from escaping from inside the underground pipe out into the atmosphere.