What’s a P-Trap?

White pipe
What is a P-trap? P-traps are U-shaped pipes in toilets and underneath sinks. P-traps hold a small amount of water that prevents sewer gases from rising up into your home. These pieces of plumbing also serve several other important purposes.

What Does a Plumbing P-Trap Do?

Whether they’re made of PVC or stainless steel, the P-traps beneath the drains in your home….

  • Trap Debris & Prevent Clogs- When cleaning your bathroom, you may notice a slow drain, indicating the P-trap has collected enough to become clogged. To prevent food waste, hair, and other things from clogging up your plumbing system, the bottom of the P-trap contains a small cleanout used to clear clogs the P-trap has contained. These clogs can usually be cleared with a plunger. However, if this does not work, you may need to call a plumber.
  • Protect Against Property Losses- Though not originally devised for this particular purpose, P-traps can also bail you out in a jewelry jam. If wedding rings, necklaces or other small prized possessions accidentally slip into the sink drain, the P-trap may catch these valuables.
  • Stop Sewer Gases from Infiltrating Your Home- P-traps are designed to prevent sewer gases from seeping from pipes into your home. Prolonged exposure to these gases, which can include methane, hydrogen sulfide, nitrogen oxides, sulfur dioxide, ammonia, and more, is more than a smelly annoyance. Prolonged exposure can cause health problems including headaches, fatigue, irritability, loss of appetite, memory issues, light-headedness, sinus infections, bronchitis, and even pneumonia. Exposure at high levels, such as those found in municipal sewers and industrial settings, can be fatal; however, levels this high are typically not found in homes. If you notice a ‘rotten egg’ smell in your home – no need to evacuate. But you should call a plumber.

Is Your P-Trap Working Correctly? P Trap ‘Traps’

P-traps may seem like simple devices, but as with all things involving human error, things can go wrong. Common issues with P-traps Mr. Rooter® Plumbing commonly rectifies include:

  • P-trap Overload A single P-trap cannot handle the wastewater of more than 2-3 water-using appliances.
  • No Tap Primer on Infrequently Used Fixtures
    On traps that are rarely used, or in very dry climates, water in P-traps can evaporate, leading to the release of sewer gases into the home. In this scenario, a tap primer (or tap seal primer) should be added. These devices inject water into the P-trap as needed to ensure a water seal.
  • Insufficient Ventilation
    Drains without proper ventilation, such as those in older homes or cabins, will be slow to empty. Improper ventilation can be identified by listening to a ‘glug-glug’ sound from another drain in the house (other than the one emptying). The lack of ventilation in the emptying drain looks for release through neighboring lines, pushing/sucking air through an adjacent P-trap, emptying water from the trap, and potentially releasing sewer gases.

What’s that smell? Hopefully not a problem P-trap. For all your plumbing mysteries, look to the experts at Mr. Rooter Plumbing for a fast resolution. Keep things flowing in the right direction. Contact us today by requesting an estimate online or call us.