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Agentis Plumbing Blog

Plumbing Diy: All About Drain Traps

Posted by Agentis on Apr 27, 2018 3:11:07 PM

 Ever wonder what that curved pipe is underneath your sink? 

Today we’re going to boost your plumbing knowledge and put a new skill into your DIY arsenal. 

Understanding the drain trap is a good step that will serve you well for diagnosing those strange odors coming up, fixing nagging leaks, or fighting stubborn clogs.


Curious how to treat a stubborn clog?

 What is the drain trap?

The drain trap is a, P-, S-, or U-shaped pipe that you see underneath your bathroom or kitchen sink. These are designed to create a barrier between the sewage system and your home. 

The reason they are angled is to allow them to always hold a small amount of water so that when the sink drains, it creates a “trap” seal. This prevents unwanted sewer gasses – like Methane, Hydrogen Sulfide, Nitrogen, and Carbon Monoxide – from coming up into your home through the fixture. 

These types of traps are also built into toilets. Same purpose. 

Larger drains, for instance, your shower or washing machine, have them as well but they are generally hidden underneath the flooring or behind a wall so they are not as visible as those underneath your bathroom or kitchen sink. 

Strange Odors in the Sink?

If a drain has not been used for a while, it is possible that the water “seal” can dry up and leave a pathway for odors to come into the house. That’s why it’s a good idea to run those sinks or fixtures that may not be heavily used on a daily basis. 

Sometimes after a longer vacation, you might notice these odors that have built up while you were gone. Generally, you can “re-seal” the trap by running water in the sink and flushing it out. If everything is functioning properly, the water should resettle at the bottom of the “U” and re-seal the drain. 

Tough Clog?

Sometimes you can develop a clog and will want to check the drain trap. If that’s the case, it’s a fairly easy process but you’ll need to be sure to do a few things before you dive into this project: 

  1. Clear the area underneath the sink
  2. Shut off the water valve underneath the sink
  3. Get a bucket that will fit underneath the pipe before you remove anything.
  4. Although it looks pretty simple – especially with a U-shaped trap – it’s may be a good idea to take a quick picture for reference or make a note to make sure you put it back correctly.
  5. Unscrew the locks nuts (you may be able to do this by hand but have a plumbing wrench handy in case their tight)
  6. With the lock nuts loosed, the trap should slide off.
  7. Once it is off, take it to another sink and rinse it out or clear any debris you find inside.
  8. Then place the trap back in place, slide it up and tighten the lock nuts.
  9. Turn on the water again and flush the sink to make sure everything is sealed properly and in working condition 

Have a stubborn drain that needs clearing? The experts at Agentis are ready to help.


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Topics: Plumbing, Bathroom Drain, Drain, Drain Trap


As a second generation family owned business, Agentis Plumbing has served Allentown, Bethlehem, Easton and the entire Lehigh Valley since 1954. Through our family-owned and operated full-service plumbing and drain cleaning Mr. Rooter franchise, we offer courteous and prompt service by fully uniformed, skilled technicians, providing emergency plumbing services with no extra charge for nights, weekend, or holidays.

Don’t just take our word for it. Here’s what our customers have to say — agentisplumbing.com/about/testimonials.

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