Shower Drain Smells Like Sewer: Causes And How To Fix

Shower Drain Smells Like Sewer: Causes and How to Fix

A smelly shower drain is a definite sign that something is wrong in your bathroom.

Bacteria in the shower drain feed on the debris in it and emit a bad smell in the process. That is one of the main reasons why your shower drain smells like a sewer.

When a shower drain smells like sewer gas, there’s probably rotting debris, draining problems, or general plumbing issues. A dry P-trap and short vent pipes can cause rotten-egg like smell in the bathroom.

Thorough cleaning of the shower drain and fixing the plumbing problems usually gets rid of the bad smell.

Causes of a Smelly Shower Drain

what causes smell from shower drain

Before you mistake the smell for the sewer line having burst, you need to know that the smell occurs due to a lack of thorough cleaning of the shower drain.

Anaerobic bacteria feed on the dirty water in the drain and emit hydrogen sulfide gas. This gas is what smells like sewage or rotten eggs. Let’s look at the causes of the bad odor in your shower drain in detail.

1. Bacterial activities

Your shower drain receives a lot of debris from soap, hair and all other sorts of dirt in your bathroom. While a large part of this is washed down, some of it is retained in the drain and the piping system.

Anaerobic bacteria will work on it releasing various gases among them hydrogen sulfide which smells like sewer gas.

2. Mold

The damp conditions in the shower drain are perfect for the growth of microorganisms such as bacteria and fungi. When mold, a type of fungi, grows on the inside of the drain, it will cause a musty stink.

This smell combines with other odors from the plumbing system to form a sewer-like smell. There are types of fungi that break down soap into sulfur compounds, one of which is the sewer-like hydrogen sulfide gas.

3. Rotting debris (biofilm)

The shower drain has a lot of debris from the compounds found in soap, hair and body products, and general dirt.

Coupled with the dampness, bacteria and fungi will act on the dirt, breaking it down into individual compounds and elements among them sulfur and its compounds.

You’ll start notice a sewer-like smell or one like a rotten egg when you step into the shower. This smell is felt mostly when showering as the water displaces gases upward and outward into the shower room.

4. Short vent pipe

vent pipe under shower drain

If the vent pipe is too short, the sewer smell will find its way into your home. It is likely the unpleasant odor is coming from another part of your house and diffusing into the shower area.

For example, the sewer smell could be finding its way into the bathroom through the sink drain. You might want to check all the areas with possible leaks to rule them out.

5. Loose pipe connections

Sewerage piping needs to be airtight. If this isn’t the case, the sewer gas will leak into your home from various points.

The common areas to check include the toilet wax ring, P-trap nuts, shower valve, pop up stopper of the sink drain, and the gooseneck.

6. Cracked or rotten drain pipes

As the sewer pipes get old, they rot or crack and start to let in the stink into your home. This is highly likely in old homes. Houses that haven’t been used for a long time may also have damaged plumbing systems.

Plastic plumbing can be eaten away by rodents while metallic ones rust and start wearing out. Any leakages in these systems can dump sewer gas into your bathroom. Routine checks will ensure they do not get into this condition without your knowledge.

7. An old toilet wax ring

replacing toilet wax ring

This wax ring keeps the sewer gas away from entering the home from the sewerage system. If it wears out, you will feel the bad smell in the toilet or bathroom.

8. Dry tap and P-trap

When the sediments in taps dry up, they will emit sewer-like smells into the bathroom or other places they are located.

The P-trap is the U-shaped part from the toilet bowl to the water cistern. The water trapped in this part keeps away sewer gases from coming back up through the pipes to the toilet bowl. If dry, the gasses will freely come back up.

P-traps can also be used on sinks to keep any erratic gases away.

9. The water heater

In some cases, the anode rod in your shower heater may react with the chemicals (such as chlorine) in the water leading to the foul smell. The best way to test this is to sample both cold and hot water from the shower.

  • Take a jug of cold water from the shower when the heater is off.
  • Take it into an area with fresh air and smell it.
  • Repeat the two steps above but this time with hot water from the shower.

If the hot water has a sewer-like smell, then the problem is with the anode rod in your water tank. Cold water hardly smells like sulfur unless the water tank is infected with bacteria.

10. Sewer back-up

When the sewer pipes are clogged, there could be a sewer back-up. This is a situation in which the sewerage materials ascend instead of draining away. The first sign is a strong sewer smell in the home.

Do not rule out a dead animal in the pipes. At times, rodents, birds and other small animals may die within your piping system leading to such awful smells. They could also cause blockage in the pipes.

Proper identification of the source of the bad-smelling gas is the first step to solving the problem when it comes to sewer-like smells in the shower room or any part of the home. Luckily, there are solutions to this unpleasant experience as shown below.

How to Get Rid of the Stinky Smell in Shower Drain

old shower drain

The process of getting rid of the smell involves various stages of cleaning the shower drain to wash and flush away the dirt.

The results are not just an odor-free bathroom, but any blockages you might have noted with your drain will be done away with.

Here’s how to stop the stinky smell in your shower drain:

1. Unblock the shower drain

If your shower drain is blocked, you may need to unlock it first. For this, there are several methods including the following:

  • Pouring hot water down the drain.
  • Using a plunger with water poured in the drain.
  • Physically pulling out the clog using your hands or a preferred tool such as a hook.
  • Using the toilet jack (also called the Electric Eel or Plumber’s Snake).
  • Use of recommended chemicals.

After that, head over to the next step which is the cleaning of the drain.

2. Clean the shower drain regularly

The strainer keeps at bay items that can cause blockage of the drain among them pieces of hair, soap remnants and others. With time, these items build up sediments on the strainer.

You will have to pull the dirt out and scrub the sediments off the strainer as part of the cleaning process. The scrubbing should take place in a basin of soapy water and an abrasive sponge or piece of cloth employed for the same.

After that, pour a cup of baking soda down the drain then wait for 15 minutes. Add a cup of white vinegar into the drain then cover it for 15 more minutes. Pour boiling water down the drain to rinse it and eliminate the odor.

How to Prevent Bathroom Odors

If you get the sewer smell from your bathroom often, you can prevent its recurrence with a simple step. The trick is pouring hot water down the drain at least once every week.

Given that the main cause of this smell is soap (it has sulfur compounds remember), hot water will dissolve all of it and wash it down the drain.

If you’ve carried out the steps above and still get the smell of a sewage, it’s time you checked the other culprit; your sewer. This is usually the culprit if you get the same smell after using the washing machine or flushing the toilet. It could be a blockage of the plumbing pipes.

If at-home solutions such as de-icing the roof vent and clearing the debris in the vent do not work, call your plumber for help. It could be a more complicated issue.

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