The Surprising Cause Of P-Trap Smells (And How To Eliminate Them)

Tired of dealing with foul scents coming from your sink or shower? The culprit is likely your P-Trap. P-trap smells can be caused by a variety of factors, such as a build-up of debris or infrequent use.

But don’t worry, dear reader, in this article we’ll take a look at how to diagnose, eliminate, and prevent these odors for good!

How to Eliminate Foul Odors Coming From Your P-Trap

P-trap smells emanating from sinks or showers are a problem that many homeowners face. A plumbing trap (P-trap) is a curved pipe located under these fixtures and has two functions:

  • The curve of the pipe is designed to contain a pocket of water (water seal) which prevents sewer gasses from entering your home.
  • It collects dirt and debris to prevent clogs deeper in your plumbing system. 

In this article, we’ll cover the possible causes of P-Trap smells and take you through various solutions that will oust the odors and leave your home smelling fresh.

P-Trap Smell: Key Takeaways

  • What Are Plumbing (P) Traps?: A P-trap is a part of your plumbing system that prevents smelly sewer gasses from entering a home.
  • Signs of a Problem: A bad sewer gas smell from your sink or shower, slow drains, or gurgling sounds.
  • What Causes It?: A bad smell from your drain pipe can be caused by infrequent use or a build-up of debris.
  • How to Fix It: Cleaning and maintaining your drains, using odor-neutralizing products, or calling a professional plumber.
  • How to Prevent: Regular cleaning of your drains’ P-traps and avoiding pouring grease down them or allowing debris to collect.

What Can Cause Your Plumbing Traps to Smell?

Sinks or drains that don’t get regular cleans can allow debris to build up

P-traps can emit foul stenches for various reasons, including:

  • Debris buildup: Over time, debris such as hair, soap scum, and food particles can accumulate in the trap, causing blockages and bacteria that lead to bad odors.
  • Infrequent use: If a sink or shower is not used frequently, the water can evaporate, leaving you with a dried-out p-trap that allows smelly sewer gases into the home. This can be exacerbated by dry climates, where evaporation can happen faster
  • Leaks: If there is a leak in the pipes leading to the P-trap, it can leave you with a dry P-trap and allow sewer odors into your home.
  • Lack of ventilation: Vent pipes are built into your plumbing to allow gasses to escape. If your vent pipes become clogged, this can lead sewer gas smells to emanate from your drains.
  • Improper installation: Sewer gas odors could be a problem if your P-traps or vent pipes are not installed correctly. Alternatively, older plumbing systems may use S-traps, which do not eliminate odors coming from your sewer lines effectively.
  • Sewer line issues: Issues with the main sewer line might also be the underlying cause.

A misfunctioning P-trap will allow sewer gasses to escape into the home, causing unpleasant odors. These unpleasant aromas can be more than just a nuisance; they can cause health issues and indicate a problem with the overall plumbing system. It is important to address these issues as soon as they are detected to prevent further issues from arising.

Sewer Gas, Food Scraps, or Other Plumbing Issues: How to Diagnose Plumbing Trap Smells

The most obvious symptom is the smell of rotten eggs or food, but additional signs such as a blocked drain or a glug sound can also indicate an issue with your P-traps.

Begin by determining whether the problem is restricted to one location or is affecting multiple sinks or drains.

If it is the latter, then it’s likely you have a larger problem with your plumbing and may need to call a professional to inspect your home.

If it is restricted to one stinky drain, then it is likely either a clog or a lack of water in the P-trap. Drains that get a lot of use, like in kitchen sinks or your toilet, will most commonly cause a stench due to clogs in the pipe. That said, you should also check the pipe and water seal for any potential leaks.

Less frequently used drains, such as a floor drain, are much more likely to be suffering from a lack of water due to evaporation.

How to Eliminate Odors Coming From Your Kitchen, Floor, or Bathroom Sink Drain


plumber using plumbing snake to clear a sink clog
Clogs are often easy to remedy

If water is gurgling, draining slowly, or not at all, then you likely have a clog that is causing the stench. The good news? Clogs are relatively common and easy to fix.

You can use a range of solutions to fix clogs, from homemade remedies like baking soda and vinegar or boiling water and dish soap to store-bought drain cleaners or plungers and plumbing snakes.

Once you have removed the clog, you should be able to run water without it backing up – if there is still an odor, then pour more baking soda down the drain. 

Dry P-Trap

unhooking pipe from plumbing trap
Check for water (or lack of it) in your p-trap

If you think you have no water sitting in your P-traps, the first thing you should do is check for leaks. To do this, pour water down the drain and inspect for leakage, particularly around the water seals.

If you can’t see a leak, then try adding more water to displace the air sitting in the trap. If you can no longer smell the funky odor then the likely culprit is evaporation.

If you have a leak, then you should fix or replace the trap and/or pipes that are affected.

More Serious Issues

plumbing vent stack surrounded by snow
Issues with multiple drains could suggest a problem with your plumbing ventilation system or the main sewer line.

If the stink is emanating from multiple sources, you likely have a more severe issue with your vent pipes or the main sewer line. First, check to see if your vent pipe is clogged by debris, and remove any you find.

If this doesn’t solve the problem, then you should call a plumber to come and inspect your plumbing.

Tips to Prevent Sewer Gases and Other Odors

  • Make sure to clean your drains regularly.
  • Avoid pouring fat or grease down the drain (particularly in conjunction with cold water).
  • Run faucets or pour water down infrequently used drains.

From Sewer Gas Smells to Fresh Air: Conclusion

P-trap smells are a commonly occurring problem faced by many homeowners. These funky fragrances can be caused by various issues, such as a build-up of debris clogging the pipe or through infrequent use allowing the water seal to evaporate. However, they can typically be easily diagnosed and eliminated.

We hope you’ve enjoyed our article, and if you have any questions or suggestions then please use the comments below.

About the author

An accomplished plumber with more than 15 years of experience in the industry, David "Fitz" Fitzgerald began as an apprentice and steadily worked his way up to become a fully licensed and certified master plumber.

With extensive training in all aspects of plumbing. David is well-versed in the installation, repair, and maintenance of plumbing systems, including pipes, fixtures, and appliances, and is able to troubleshoot and solve even the most complex plumbing issues.

He loves to share his wealth of knowledge and looks forward to engaging with the community here on No Hassle Plumbing.

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