All shower use a 2 inch drain and 2 inch pee trap. Bath tubs can use a 1 - 1/2 drain and pee trap depending on your local code.
There is no standard for the depth of a shower drain P-trap, as it is only based on the size of pipes or fittings used. It would help if you didn't worry about its depth as long as it is securely covered and functioning properly.
Types of Shower Traps
All shower trays will fit either a 90mm or a 50mm shower trap.
Ideally, it should be as close to your shower inlet as possible. The further away the P-trap is from your shower drain, the easier it is for foul smells and drain bugs to make their way into your shower. Also, a P-trap for a shower must be at least 2 inches in diameter.
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.
How to determine the required installation depth of the shower drain? The top of the shower drain should be at the same level or max. 2 mm (1/16”) lower than the finishing floor.
Shower p-trap: This type is often located at the center of the shower by the drain. Following the same method, measure and cut the drain line. When installing the fitting to the drain, one of four types of connections can be used: threaded, solvent, or rubber caulking.
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.
You might be wondering: Should there be water in the trap shower? You might be surprised, but the answer is yes. Shower waste traps are designed in a way to always have a little water sitting in the shower tray in order to prevent any malodorous gasses from the sewer to enter your bathroom.
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.
No fixture shall be double trapped. Exceptions to the separate trapping requirements are as follows: (1) Fixtures having integral traps. (2) A combination plumbing fixture may be installed on one trap provided one compartment is not more than 6 in.
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.
Do you know the proper way to size a P trap on an HVAC unit? The pull of the water to the drain has to exceed the sucking of the supply fan (“negative pressure”). Rule of thumb… add 2.5” to the static pressure before the fan (return and internal to the unit) and that's the long end (closer to the drain of the unit.
The trap is usually attached to the end of the tailpiece, and tailpieces are typically between 6 - 8 inches long (though I've seen up to 12). So the "standard" height of a trap would be, 6 - 8" below the fixture.
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 Optimal Slope for Effective Drainage
For optimal water drainage, it's advisable to ensure that the shower floor maintains a gentle gradient of approximately 2-4 percent. This corresponds to a decline of ¼ to ½ inch for every 12 inches from the shower enclosure to the drain.
According to the International Residential Code, the maximum vertical distance between the sink drain and the entrance to the p-trap is 24 inches. Be aware that it'll make a fair bit of noise dropping that far.
Build-up Of Biofilm
Biofilm is a thin, slimy layer of bacteria that can grow from all the water, soap, shampoos, and body oils that go down the drain. This can then accumulate inside the pipes, causing your shower drain to smell like rotten eggs.
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.
We recommend installing your shower drain against the wall (three-sided installation). By doing so, you have a one-sided slope that offers the easiest installation with less tile cutting necessary. Another option is to place the shower drain free-in-the-floor.
To eliminate odors coming from a dry p-trap, pour half a gallon of water into the trap to restore the barrier.
The minimum size drain for a shower with one 2.0 G.P.M shower head operating at one time shall be one-and one-half inches. The minimum size drain for a shower with more than one 2.0 G.P.M shower head which may operate simultaneously shall be two inches.