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Does a Shower Drain Need a P-Trap

When it refers to a P-trap, numerous homeowners do not understand drain configurations and functions. Whether it is a P-trap sink, U-shaped trap, or S-trap, if you are not familiar with them, then you will not know how to properly make great use of or replace them. Read on, this article is one of the bridges forging bonds between you and the shower plumbing system.

Basic Information of a P-Trap
Do all shower drains have traps? P-trap or S-trap?

All shower drains must be installed with P-traps, which is an important part of the building piping system. As a fixture in the shower plumbing diagram, it provides a strong guarantee for the pipeline. The S-type trap was considered to be the standard drainage device in the early days, whereas its utilization rate is not as high as P-trap nowadays in that after the full tank is drained, it is easy to siphon and cause the trap to dry out. After replacing S-trap with a P-trap sink or P-trap drain, the “sucking” action is well improved. First of all, the ventilation device balances the air pressure inside the pipe, which greatly reduces the possibility of siphoning caused by negative pressure. Secondly, an extended pipe plays a critical role in reducing gravity. The minimum shower drain P-trap size is 2inch, the bathroom P-trap sink is 1.25inch, and the kitchen P-trap sink is 1.5inch.

What is the purpose of a P-trap?

The purpose of the P-trap sink or P-trap drain is to keep some water in the pipe so as to prevent the shower drain smells of the sewer from overflowing to the ground and small organisms crawling up the shower space. When you smell a peculiar smell in the shower space or in the bathroom, you should first check whether the shower drain trap is in a dry state. If there is no water in the pipe, it can be assumed that the smell of the sewer has spread to the room. What needs to be cautious is that the main components of sewer gas are methane, hydrogen sulfide, and sulfur dioxide. Long-term exposure to these chemical gases will lead to serious health problems, such as headaches, nausea, and bronchitis. Thus, you’d better pull some water to the P-trap sink or P-trap drain in time to suppress the shower drain smell return and protect your health. 

What are the components of a P-trap?
01. Inlet
In a shower plumbing diagram, the inlet of the shower drain P-trap is a vertical pipe where the wastewater enters, playing a significant role in directing water to the down-bent pipe.
02. The Downward bent pipe
The downward-bent pipe, regarded as a U-shaped, acts as a wastewater collector to form an airtight seal, preventing shower drain smells and cockroaches from rising up into the home. 
03. Outlet
In a shower plumbing diagram, the outlet presents a horizontal structure. As a pipe that balances the air pressure, it effectively guides wastewater to leave the shower drain trap.

What is the Location of a P-Trap?

The location of the P-trap is extremely evident. The plumbing code specifies the maximum acceptable distance of 5 feet for installation between the shower drain and P-trap. Ideally, it should be installed directly below the bottom of the shower drain, such as a 304 stainless steel square linear shower drain of HUCKLE, to make use of gravity that can scientifically direct water to flow into the pipe. The farther the P-trap is installed from the shower drain, the easier it is for the shower drain smells to overflow. 

How to Clean a Shower P-Trap?

Timely cleaning of the P-trap sink is of great importance not only to reduce the shower drain smells coming up from the sewer but also to prevent the blockage of the drainage system. The P-trap sink is laborious to clean, while you can split the second part--the downward bent pipe, and keep the inlet and outlet in place. If the P-trap sink is blocked, it can be cleaned with a screwdriver and brush. If necessary, you can choose a plumbing snake for further cleaning. In addition, a mild sewer cleaner can effectively keep the p-trap clean. Vinegar, blended with water, is also a good choice.

How to Install a P-Trap? 
01: Cut the appropriate length of the drain pipe and use a file to remove the burrs on the edge of the pipe. Take out the rubber joint and place it at the interface.
02: Install connecting accessories on the shower drain and tighten the nut clockwise.
03: Change the direction of the shower drain appropriately to align it with the shower drain trap.
04: Smooth out the burrs of the PVC pipe and connect it to the drainpipe, making sure the shower drain trap is directly placed under the outlet of the shower.
05: Use a marker to mark all the positions that have been determined.

06: According to the measured marks, apply PVC cement to the inner side and glue all parts together.

07: Wait for all glued joints to dry to be ready for use.

How to Replace a P-Trap Sink?

01. First, place an empty bucket under the old trap to receive the wastewater from the replacement process. Loosen the sliding nut fixed on the trap arm. After emptying all the water in the old drain pipe, put the sliding nut and washer aside.
02. Prepare a new trap. Slide two sliding nuts to the end, and adjust the length of the arm to adapt to the in and out of the drainpipe opening. Subsequently, the non-slip nut is applied to the connector.
03. Fix the trap bend, connect one side to the sink tailpiece, and the other side to the curved end. Adjust the nut and tighten it on the thread, forming a sealed environment with a non-slip gasket.

04. After all the P-trap sink accessories are connected, tighten the nuts. Finally, release water to test whether the trap is installed properly without leakage.

At this point, you have basically understood what is a P-trap sink or P-trap drain and are also familiar with its working principle, cleaning, installation, and replacement. The weekly shower drain cleaning can ensure the normal operation of the P-trap and prolong its service life. If you encounter difficult problems, it is recommended to call a dedicated plumber to deal with because the internal structure of the pipeline is complicated, and its operation is related to multiple households.