No Claptrap — Just the Straight Rap on Plumbing Traps

What Is a Trap?

Draining sewage and waste out of your Toronto home or office can get smelly. That’s because fumes from gases like methane, nitrogen, hydrogen sulfide, and carbon monoxide are a by-product of waste. The job of a plumbing trap is to keep these gases (and their odors), and also small vermin, from entering your home or office via the drain pipes. How does a plumbing trap work? It works by creating a water seal, allowing a small amount of water to be retained in the trap and preventing anything from flowing back up through the pipe. All plumbing fixtures — sinks, toilets, tubs, showers, utility sinks, washer drains, etc. — have a trap of some kind.

Types of Traps

Some traps are integral with appliances and some are separate, located beneath the pipe so that waste and water drain into the trap but not back out. Toilet traps are often integral, while traps for sinks are separate, also known as attached traps. Large industrial traps found outside a dwelling that keep the main line from becoming odiferous are called gulley traps. Traps attached to sinks, washing machines, and other draining appliances are called p-traps if they drain through a wall, or s-traps if they drain through the floor. There are also floor traps (or Nahini traps) that work with a grate system in the floor of a tub, shower, or basement for draining. Another common trap is the final trap that separates residential waste from the main sewer, called an intercepting trap.

Plumbers must adhere to a specific set of codes that keep your Toronto home safe. These codes designate which type of pipe (PVC, cast iron, etc.) can be used for each type of drain system and trap. They also regulate the size of trap that must be used (a plumber cannot install a trap larger than the diameter of the drain line), how far down in millimeters the trap must be placed to ensure proper drainage, that traps are self-cleaning, and that they do not depend on moving parts to create the water seal. There are more specialized traps for specific purposes — for example, an upstairs toilet would require a “q” trap instead of an s- or p-trap — but the intention of the trap remains the same. You should consult your Toronto plumber, who will know the exact codes and proper application of each drainage system component.

Repairing a Trap

There are many reasons why a plumbing trap’s seal may need repair. One cause is trap siphonage, where velocity from another location builds up enough to completely drain the water seal from the trap. Another is back pressure, the opposite of siphonage: a large amount of waste is expelled, creating compression in front of it that can backfire into the building. A further culprit is capillary action, where inappropriate items have lodged in the drainage system and are blocking the trap seal by drawing up the water. While these issues are sometimes manageable for an intermediate DIY-er, you should probably call your Toronto plumber to get a work estimate, just in case the problem is more involved or compounds as you begin to resolve it.