A p-trap, the curved pipe section that you can usually see under sinks, performs a very important function for all plumbing fixtures in a structure. Hence, bathtub and shower drains need p-traps, too; otherwise, the safety and health of every person living in a house will be compromised by sewer gas making its way up the building.
About Sewer Gas
How does sewer gas compromise the health and safety of people living in a property? Aside from smelling awful, it contains methane, a combustible gas that does harm to the body when inhaled. Thus, by taking sewer gas in the home for granted, you increase the risk of an explosion, one that can adversely affect your home, but also the rest of the community.
Enter the P-trap
A p-trap, as stated above, is a curved section of pipe that you often see under the sink. Although not really important when it comes to bringing wastewater down the drain and the sewer, a drain system without this is inviting sewer gas to travel up drainpipes until it eventually makes its way out of drains.
How does the trap prevent sewer gas from entering the house? As mentioned, it has a curved shape, and this prevents some of the water from going down. The trapped water, in turn, stops the rise of gas.
Aside from p-traps, vent pipes also have an important role in preventing the entry of sewer gas into the home. Without them, sewer gas can accumulate down the sewer, and this puts occupants at risk of an explosion. Vent pipes work by accommodating these gases and allowing them to escape through the roof. Yes, they look similar to fireplace chimneys, except that they let sewer gases out instead of smoke.
Preventing Trap Failure
A trap can fail to block sewer gas from coming up and entering the home through different drains. This happens if the trap does not remain filled with water or if a leak has developed on it. Hence, it is important that one uses the sink, bath tub, or shower on a regular basis. If one suspects that a leak has developed on the trap, a plumber should be contacted right away so it is fixed before it becomes worse.
However, one should not just contact any plumber in the area. The right plumbers to count on are those who have the skills, licenses, and equipment to do the job right.