As a homeowner, there’s nothing more unpleasant than walking into your house and being
greeted by a foul sewer odor. Not only is it unpleasant, but it can also indicate that
something is seriously wrong with your plumbing system. Sewer odor in your house should
never be ignored as it can be a sign of various issues that require immediate attention. In
this guide, we will explore the causes of sewer smell in your house, how to identify the
source of the odor, and the steps you can take to resolve the problem.

What Does Sewer Gas Smell Like?

Before we delve into the causes of sewer odor in your house, it’s important to understand
what sewer gas smells like. Sewer gas produces an unpleasant odor that resembles the
scent of rotten eggs. This distinctive smell is due to the presence of hydrogen sulfide in the
gas. If you ever encounter this foul odor in your home, it’s crucial to take action
immediately.

Common Sources of Sewer Odors Inside the House

When you notice a sewer smell in your house, your first instinct might be to blame the
toilet. However, sewer odors can originate from various sources within your home’s water
systems. Let’s explore some of the common sources of sewer odors and how to identify
them.

Odors From Your Shower Drain

One of the most common sources of sewer smell in your bathroom is not the toilet, but
rather the shower drain. A smelly shower drain is often the result of biofilm accumulation, a
clogged drain, a problem with your P-trap, or leaking pipes. Let’s take a closer look at each
of these issues and how to address them.

Biofilm Accumulation

Biofilm accumulation occurs when substances such as body oils, conditioner, shampoo,
soap, and skin cells accumulate along the P-trap and vertical pipes underneath your shower.
This accumulation leads to the release of a sewage smell from bacteria and decomposing
debris. To eliminate the odor caused by biofilm, you can try the following steps:

  1. Use a screwdriver to remove the shower drain.
  2. Boil between five and 10 quarts of water and let it cool to 150 degrees Fahrenheit.
  3. Slowly pour the hot water down the shower drain.
  4. Pour one cup of white distilled vinegar in after the water.
  5. Immediately after pouring the vinegar, add half a cup of baking soda.
  6. Wait for two hours, then pour a gallon of hot water into the shower drain.
  7. Finally, run a drain brush through the drain to clear out any remaining debris.

If the sewage smell persists after cleaning your shower drain, it’s best to contact a
professional plumber to examine your water system.

Clogged Drain

A clogged drain can also cause a sewer smell in your shower. Hair, dirt, mineral deposits,
soap scum, and small items can all contribute to a shower drain clog. To unclog the shower
drain, you have a few options:

  • If the clog is close to the surface, you can try pulling it out with your hand.
  • Pouring hot water or a chemical cleaner down the drain may dissolve the clog if it is
    accessible.
  • Use a plunger or a hand auger (drain snake) to clear the clog.

It’s important to unclog the drain properly to avoid damaging your pipes. If you’re unsure,
it’s best to contact a professional plumber for assistance.

Dry P-Trap

A dry P-trap can also be a common cause of sewer odor in your bathroom. The P-trap is a U-
shaped pipe designed to hold water and prevent sewer gases from entering your home. If
you don’t use your shower often, the water in the P-trap can evaporate, causing a sewer
smell. To fix this issue, simply turn on your shower and let the water run for a few minutes
to refill the P-trap. If the smell persists, there may be a leak or other issues with the P-trap,
which would require the expertise of a professional plumber.

Leaking Pipes

Leaking pipes under your shower or in the bathroom walls can also cause a sewer smell.
Loose-fitting pipes or perforations due to corrosion or chemical damage can lead to leaks. If
you suspect leaking pipes, it’s best to contact a plumber for a thorough inspection and
necessary repairs.

Odors From Your Toilet

If your bathroom smells like sewage, the odor may be coming from the toilet. Common
causes of a sewer smell from the toilet include improperly installed or cut vent pipes,
broken or loose seals, and septic blockages. Let’s explore these issues in more detail.

Improperly Installed or Cut Vent Pipe

An improperly installed or cut vent pipe can cause sewage odors to enter your bathroom.
The vent pipe helps regulate air pressure in your plumbing system and redirects odors
outside your home. If you suspect an issue with the vent pipe, it’s best to contact a
professional plumber to diagnose and resolve the problem.

Broken or Loose Seal

A broken or loose seal between the toilet and the drain pipe can also cause a sewer smell. If
you notice the smell and the toilet bowl doesn’t fill up normally, it could indicate a broken
seal. Additionally, water leakage from a seal can attract bacteria, resulting in a foul odor. To fix this issue, you can try applying caulk to the toilet’s seals and bolt holes. If the toilet is
loose or damaged, it may require professional repairs or replacement.

Septic Blockage

Flushing non-biodegradable items down the toilet can lead to septic blockage and a sewer
smell in your bathroom. To prevent this issue, avoid flushing anything other than waste and
toilet paper. If you suspect a blockage, you can try using a plunger or a drain snake to
remove the obstruction. In severe cases, it’s best to contact a professional plumber for
assistance.

Odors From Your Sink

A sulfur-like smell from your bathroom or kitchen sink can be quite unpleasant. This odor is
often caused by buildup in the sink’s overflow or a dry P-trap. Let’s explore these issues
further.

Buildup in the Overflow

Many sinks have an overflow mechanism to prevent spills. Over time, grime and mildew can
accumulate in the overflow, leading to a sewer smell. To clean the overflow, you can follow
these steps:

  1. Use a small bottle brush to scrub the interior of the overflow area and remove any
    debris.
  2. Mix a solution of half water and half chlorine bleach.
  3. Apply the solution to the overflow area with the bottle brush to eliminate bacteria
    and odors.

If the odor persists, it’s best to contact a professional plumber to examine your sink.

Odors From Your Washing Machine

If you notice a sewer smell in your house while doing laundry, the washing machine may be
the culprit. The common causes of a sewage smell in a washing machine include improperly
installed P-traps, drain or vent clogs, and even issues with the water source. Let’s explore
these issues in more detail.

Improperly Installed P-Trap

Washing machines also require properly installed P-traps. If the flexible drain hose of your
washing machine is inserted too far into the drainage box, it can prevent the P-trap from
working correctly, causing odors to seep into your home. To fix this issue, ensure that the
drain hose is positioned properly, allowing the P-trap to function as intended.

Drain Clogs

Clogs in the washing machine drain line can also cause a sewer smell. Hair, soap residue,
and other debris can build up over time, leading to bacterial growth and unpleasant odors.
To address a drain clog, you can try using a drain snake to remove the obstruction. If the
clog persists, it’s best to contact a professional plumber for assistance.

Vent Pipe Clogs

Vent pipes are essential for proper plumbing ventilation and preventing sewer smells from
entering your home. If the vent pipes become clogged, odors can leak into your house. To
check for vent pipe clogs, you will need to access your roof and inspect the pipes for any
obstructions. If you encounter any issues, it’s best to consult a plumber for safe and effective
removal of the clogs.

Odors From Your Water

If you notice a sulfur-like smell when you turn on the tap, it may indicate an issue with your
water source or water heater. Bacteria in the water heater or high levels of hydrogen sulfide
in the water can cause unpleasant odors. Let’s explore these issues further.

Bacteria in Your Water Heater

If the smell is only noticeable when using hot water, it’s likely an issue with your water
heater. Bacteria colonies can establish themselves in the water heater if the temperature is
too low or the heater has been turned off for an extended period. Increasing the
temperature of the water heater and flushing the system can help eliminate bacteria and the
associated odor. However, it’s crucial to exercise caution when adjusting the temperature to
avoid burns.

Hydrogen Sulfide in Your Water

If your water smells bad regardless of temperature, it may indicate the presence of
hydrogen sulfide. Highly concentrated amounts of hydrogen sulfide produce a strong sulfur
smell in the water. To address this issue, it’s best to have your water tested by a
professional lab to determine the presence of contaminants. Based on the test results,
appropriate filtration or treatment methods can be recommended.

Odors From Other Areas

In some cases, you may notice a sewer smell in your yard or basement that is not directly
related to a bathroom or laundry room. This odor can be caused by issues with your home’s
cleanout or sewer lines. Let’s explore these issues further.

Missing Cleanout Plug

Cleanout plugs are designed to cap cleanout lines, which are access points to the main
sewer line in your yard. If a cleanout plug is missing or broken, gas can leak into your house.
To fix this issue, you can purchase a replacement plug from a hardware store or contact a
plumber for assistance.

How to Get Rid of a Sewer Smell

Once you have identified and resolved the source of the sewer odor in your house, you may
still need to address lingering smells. Here are some steps you can take to freshen your
home and eliminate any remaining odors.

Let in Some Fresh Air

Open all the windows in your house to allow fresh air to circulate. Ventilation can help
remove the odor from the air and provide a refreshing change. If the weather doesn’t permit
opening windows fully, crack them open slightly or open them for short intervals to
promote air circulation.

Remove the Odor From Your Carpet

If your carpets have absorbed the sewer odor, you can neutralize it with baking soda.
Simply sprinkle baking soda on the affected areas, leave it overnight, and then thoroughly
vacuum it in the morning. This will help eliminate any lingering odors trapped in the carpet
fibers.

Neutralize Your Furniture and Soft Surfaces

If the sewer smell has permeated your furniture or other soft surfaces, you can use white
vinegar to neutralize the odor. Mix equal parts water and white vinegar in a spray bottle
and spritz it onto the affected surfaces. The vinegar will help eliminate the sewer odor, and
the vinegar smell will dissipate over time. It’s always a good idea to spot-test the vinegar in
a hidden area first to ensure it doesn’t cause any damage or staining.

When to Seek Professional Help

While many sources of sewer odor can be resolved with DIY methods, there are instances
where professional help is necessary. If you encounter a sewer backup, overflowing drains,
or suspect issues with your main sewer line, it’s best to contact a professional plumber
immediately. These issues may require specialized equipment and expertise to resolve
effectively and safely.

Your Trusted Sewer and Drain Specialist in the Greater Seattle Area

At NW Sewer and Drain, we understand the frustration and concern that can arise when you
experience sewer odor in your house. As a trusted sewer and drain specialist serving the
greater Seattle area, we have the knowledge, expertise, and state-of-the-art equipment to
diagnose and resolve even the most complex sewer odor issues. Our team of experienced
professionals is dedicated to providing exceptional service and ensuring your peace of
mind.

Sewer odor in your house is not something to be ignored. It can indicate various issues with
your plumbing system, ranging from simple clogs to more complex problems. By
understanding the common sources of sewer odor and following the steps outlined in this
guide, you can identify and resolve the issue promptly. However, if you’re unsure or
encounter persistent sewer odor, it’s always best to seek the assistance of a professional
plumber. With the help of experts like NW Sewer and Drain, you can rest assured that your
sewer and drain issues will be resolved efficiently and effectively, allowing you to enjoy a
fresh and odor-free home.

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