Beneath a kitchen or bathroom sink drain is a pipe with a sharp bend in it. This p-trap has a pair of reasons for its design. These traps prevent sewer gases from entering the home and stop heavy items that have fallen down the sink from being completely lost in the plumbing. You must have a p-trap installed under your sink if you want your home to pass inspection in many places, where the building code requires them. Even if they are not required, you should understand the practical purpose for installing a p-trap.
As its name suggests, the p-trap vaguely resembles the letter “p” when turned on its side. The u-shape bend in the pipe forms the curve of the “p”. The straight extension leading from the p-trap to the main drain line in the wall looks like the stem of the letter “p”. Where a curved pipe drain helps you to determine if you have a p-trap or a s-trap. P-traps exit into the wall behind the sink, but s-traps bend back down and drain into the floor.
A p-trap should be installed where possible because p-traps can be attached to a vented drain pipe where s-traps cannot be vented. In some places, an s-trap may be illegal if the horizontal run after the bend is not twice the diameter of the pipe, according to Rex Cauldwell in “Plumbing Complete: Expert Advice from Start to Finish.”
The types of p-traps available are based on the material they are made from. For longevity, opt for PVC p-traps. These are made of white plastic and are simple to install by hand without specialty tools. Plastic p-traps have nylon connectors that screw tight by hand with the twist of the plastic nut. The only downside to these p-traps is their garish appearance. For most homeowners, this is not an issue because the p-trap is located in a cabinet below the sink.
For homes with exposed piping below the sink, chrome p-traps are a more decorative option, but they do not last as long as plastic p-traps. These must be installed using a pipe wrench to tighten the connections and pipe joint compound to connect pieces of the pipe together. This installation is worth the effort when it is needed, because a bright, metal p-trap will look better in exposed places, compared to a plastic p-trap.
TRAPPING FALLEN ITEMS
If you drop a ring down a sink drain, it will not immediately be washed down to the city sewer. Heavy items such as rings or coins can be caught in the p-trap if you shut off the flow of water immediately to prevent the water flow from pushing the object out of the p-trap.
With a bucket under the p-trap, remove the nuts holding the trap to the rest of the plumbing. Turn over the bend of the p-trap to empty the water and your fallen object into the bucket. Reattach the p-trap to your drain according to the installation directions for the type of p-trap you have – chrome or plastic.
TRAPPING SEWER GAS
Even if you are meticulous about never dropping things down the drain, you still need a p-trap under your sink to keep gas out. Sewer gases can rise through the drain pipes in your home, but the u-shaped bend in the p-trap collects water. This water blocks the gases from rising up into your sink. If sewer gases enter your home, they bring a noxious odor and possible headaches and respiratory ailments to those who smell the gases, according to Merle Henkenius in “Ultimate Guide to Plumbing: Complete Projects for the Home.”
If you are having a sewer smell in your home or business, call us today at 843.236.7142 so we can come diagnose the issue and get your plumbing working properly again.