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Smell Sewer Gas in Your House? Try This DIY Remedy Before Calling a Plumber

As the owner of an older home, I researched this plumbing problem and successfully rid my home of it without the need to call a pro.


Don't Ignore Sewage Smell in the House

If you smell a noxious sewer-like odor inside your home, chances are it is sewer gas escaping from the drainage system. Not only does it smell gross, but the methane and bacteria it contains can be dangerous to your health, causing headaches or even more serious ailments.

Even scarier, high concentrations of methane gas are combustible, which can cause an explosion. If you notice this distinctive, foul odor, do not ignore it.

Possible Causes for the Sewer Smell:

  • sewer back-up
  • leaks from rotted or cracked drain pipes
  • a clogged drain
  • loose-fitting pipe connections
  • a stopped-up or too-short vent pipe
  • toilet's wax ring is old
  • a dry trap

Before you call the plumber, however, there are some simple DIY actions that may eliminate the problem quickly at little or no cost. Below, you'll find out how to get rid of the smell of sewer gas emitting from a shower drain due to a dry trap or a mild clog.

Plumbing fixtures and their connecting systems that are correctly designed and installed are normally odorless. However, even the best plumbing may sometimes allow sewer gas into your home due to a simple problem that can be easily checked and simply solved. If the problem persists, then it’s time to call in the professional—a plumber.

How to Get Rid of Sewer Gas Smell

DIY Shower Drain Sewer Smell Removal

  1. Pour 1/4 cup of baking soda into the drain.
  2. Follow with one cup of white vinegar.
  3. Let that sit for two hours with the bathroom door closed.
  4. Slowly pour a gallon of hot water down the drain.
  5. After 15 minutes, run cold water for 10 minutes to thoroughly rinse the vinegar down. This step is very important, so don't skip it.
  6. Pour 1/2 cup chlorine bleach into the drain and let it sit for another two hours with the bathroom door closed.
  7. Rinse with another gallon of hot water poured slowly.
  8. Let cool water run for 10 minutes. By now, ample water should be standing in the “U” curve of the P-trap.
  9. The last step is to pour four ounces of mineral oil (plain cooking oil will work in a pinch) into the drain. The oil floats on the water in the trap and slows evaporation.
  10. Optional: Use a screwdriver to remove the trap if you want to replace it. You can also remove the trap to clean it out.

Warning: Never mix bleach and vinegar, or you will create toxic chlorine and chloramine gas. Step 6 is crucial to avoid this danger.

What you'll need: White vinegar, baking soda, bleach, mineral oil, and hot water.

What you'll need: White vinegar, baking soda, bleach, mineral oil, and hot water.

How Does Sewer Gas Get Inside Your Home?

Every drain in your home’s sewer system should have a “p”-shaped trap that is properly vented. These drains trap water, creating a seal or barrier that will keep sewer gas out of your home.

If one of these drains is rarely used, such as in a guest bathroom, the water creating the protective seal will eventually evaporate. This is a formula for trouble that can allow stinky sewer gas to seep into your home. Simply running the water might solve this problem.


P-Traps, Vents, and Drains: How They Work

Let’s consider how the plumbing for this stand-alone shower in my home operates. Water from the city water system enters through the showerhead while faucets control the water pressure and supply. When water drains from the shower, it goes into the city sewer system.

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My shower, indeed every plumbing fixture in my home, should have two items working together to keep sewer gas out:

  1. A p-trap that holds water in a “U” shape of the pipe and forms a seal.
  2. A vent system that allows air in to equalize pressure and let sewer gases escape up the stack to the outside.

In short, the properly-vented p-trap prevents back pressure from letting sewer gas into my home. The vent is a critical component of this system because the pressure in sewer lines may fluctuate.

A p-trap.

A p-trap.

What Is a Dry Trap?

My research led me to believe that my stinky problem might be the easiest type to resolve: A dry trap. Since my guest shower had remained unused for a long time, the trap under the basin wasn't holding enough water to prevent sewer fumes from seeping up into the room. Often, simply running the water can resolve this issue.

Is It Okay to Pour Boiling Water Down the Drain?

While I advocate pouring hot water down the drain, what about boiling water? Is it likely that boiling water in the drain might crack a pipe? I asked an engineer about this issue, and he told me that boiling water won't damage metal pipes. Even if your home's plumbing includes PVC pipes and joints, using very hot water shouldn't hurt them, but don't let the water boil.

PVC pipes don't need regular dousing with water over 175 degrees Fahrenheit (and water boils at 212 degrees Fahrenheit), or the joints might melt. If you aren't certain whether or not your plumbing system includes PVC pipes and joints (or even rubber fittings), don't let the water heat to boiling or even the about-to-boil stage. If the water is hot (less than 175 degrees F.), it should do the trick.

What if This Simple Solution Doesn't Work?

If the odor persists after the vinegar-baking soda-bleach-hot water-mineral oil technique I used, the sewer gas invasion might have been caused by something other than a dry p-trap.

Leaks, rotted or cracked drain pipes, clogs in the drain, or a stopped-up vent pipe are other potential stink-makers. Had I still smelled that nasty odor when I opened the bathroom door the next morning, stronger measures would have been in order.

I don't have the DIY expertise to test or resolve more difficult issues, so it would have been time to call in the professional—a licensed, bonded, and insured plumber. I already have the phone numbers of two such plumbers on my speed dial (see next paragraph), but anyone looking for a trustworthy plumber should use an Internet search engine for a national or local directory of plumbers who are licensed, bonded, and insured. You don't want to take a chance on someone who may charge cheaper rates, but can't be held accountable for work, including any damages to your property.

My Experience With Sewer Gas

I didn’t know anything about p-traps or their function until a recent unpleasant incident forced me to do some hurried research. Here’s the background. There are three showers in my home. Two of them are regularly used, but the third is rarely used at all. In fact, it had not been used for months at the time this situation occurred.