Why Does My House Smell Like Sewage?

woman plugging her nose
A bad smell can indicate that something is wrong — especially if there is a sewage smell in your house.

Septic tank smells in your bathroom, kitchen or laundry room may indicate a broader issue than backed-up plumbing. It could come from the sewer itself, which requires immediate action. If the problem is a dried-out P-trap, the solution could be as simple as running some water from the faucet. If the issue is a broken vent pipe, you may need to call for professional assistance to resolve it.

Along with being unpleasant, a strange sewage smell could be hazardous for your health. One of the primary gasses in sewage is methane, and if it accumulates in large amounts, it can become highly flammable. If untreated, sewage gasses can leak methane into your home.

Prolonged or high exposure to methane can cause sewer gas poisoning with symptoms such as weakness, headaches, dizziness, loss of coordination, nausea, vomiting, loss of consciousness and even suffocation. If you notice a sewer gas smell in your house, it is important to address it immediately.

Unusual sewer smells are not something to ignore. However, finding the source of the odors can be difficult — most of us automatically assume it must come from the toilet, but problems can hide in many of your home's water systems, including the shower and washing machine.

We have compiled this guide to help you trace the source of a sewage smell in your home. Once you discover the cause of the odor, we will walk you through some troubleshooting steps to try to resolve the issue — however, sometimes, only a professional can fix a sewage problem.

What Does Sewer Gas Smell Like?

Sewer gas produces an unpleasant odor that resembles the scent of rotten eggs. This is because it is a result of natural human waste breaking down. The rotten egg odor is due to the presence of hydrogen sulfide in the gas. If you are wondering how to find the sewer smell in your house, try to locate where the odor is the strongest.

Common Sources of Sewer Odors Inside the House

If you smell sewage in your home, you may assume it is coming from the toilet. However, odors sometimes remain even after you have cleaned your bathroom and freshened the air.

When cleaning does not eliminate the odor, you are most likely dealing with a more significant issue. Examine the following areas of your home and notice if the smell gets stronger in specific locations — your nose will be your first clue in finding the source of the sewage smell.

Odors From Your Shower Drain

One of the most common sources of a sewage smell is not the toilet — if you notice a foul sewage smell in your bathroom, examine the drain in your shower.

A smelly shower drain typically results from one of four issues: biofilm accumulation, a clogged drain, a problem with your P-trap or leaking pipes.

1. Biofilm Accumulation

When we shower, we use many different products. Body oils, conditioner, shampoo, soap and shaving cream wash down the drain along with natural debris like skin cells and hair. Over time, these substances often accumulate along the P-trap and vertical pipes that run underneath your shower.

This accumulation is called biofilm. As it builds up, biofilm begins to release a sewage smell from bacteria and decomposing debris. The bacteria emit a sticky substance that allows them to cling to the side of your pipes, making them difficult to remove without specialized products.

Eventually, this sewage odor becomes noticeable in the entire bathroom, not just in the shower or bathtub.

How to fix the problem: Typically, eradicating biofilm and the shower drain smells it creates is an easy process that does not require a plumber. To get rid of the sewage odors from your bathroom, you will have to unclog the debris that is feeding the bacteria in the drain.

Make a DIY, all-natural cleaner using hot water, baking soda and white distilled vinegar. Complete the following steps to strip biofilm from your pipes:

  1. Use a screwdriver to remove the shower drain.

  2. Next, boil between five and 10 quarts of water. Let the water cool to 150 degrees Fahrenheit before slowly pouring it down the shower drain.

  3. Pour one cup of white distilled vinegar in after the water.

  4. Immediately after you pour the vinegar, pour half a cup of baking soda down the drain.

  5. After two hours, dump a gallon of hot water into the shower drain.

  6. Finally, run a drain brush through the drain to clear out any remaining debris.

If the sewer gas smell in the bathroom persists after you have cleaned your shower drain, contact a professional plumber to examine your water system.

2. Clogged Drain

In some cases, there may be more in your drain than just biofilm buildup. If you notice that your shower drain smells like sewage and drains slowly or not at all, you may have a shower clog. Shower clogs prevent water from properly draining, and they trap grime that builds up over time. You may have a clog in your shower from any of the following substances and debris:

  • Dirt

  • Hair

  • Mineral deposits

  • Sand

  • Soap scum

  • Small items

Shower clogs often form from a combination of debris. When hair or small items bind with soap scum, they form a firmer blockage that obstructs water flow. If a clog is causing a sewage smell in your shower, removing the clog from your drain should also remove the odor.

How to fix the problem: To unclog the shower drain, you have different options. If the clog is close enough to the surface, you can pull it out using your hand. However, in some cases, it may be too far down the drain to reach. Pouring hot water or a chemical cleaner down the drain may dissolve it if it is out of reach.

If you are looking for a chemical-free way to unclog a shower drain, try using a plunger to bring the clog closer to the surface. You could also use a hand auger, also known as a drain snake. Purchase a hand auger from a hardware store, and find one that is flexible enough to maneuver through your pipes.

If you do not have time to visit a hardware store, you can also make your own drain snake. Straighten a wire coat hanger and leave the end curved like a hook. This will allow it to grab anything blocking your drain. Gently ease your store-bought or homemade drain snake into your shower drain until you feel it hook the clog and then carefully pull it back up.

It is important to unclog the shower drain correctly to avoid pipe damage. If you are unsure about removing the clog without damaging your pipes, you can contact a plumber to remove the clog for you.

3. Dry P-Trap

Another common cause of a septic smell in the house includes a dry P-trap.

The P-trap is a U-shaped pipe designed to trap and hold water. When it is working correctly, a P-trap is supposed to hold enough water to prevent gasses and odors from the sewer from creeping up your drain.

If you do not use your shower often, the water could merely have evaporated from the P-trap. However, if you frequently turn on your shower and still notice a sewage smell from your drain, it may indicate a more severe problem. For example, your P-trap could leak, preventing it from holding water.

How to fix the problem: A dry P-trap smell can be easy or difficult to fix, depending on the reason it is dry.

If your unused bathroom smells like sewer, it may be because the P-trap is dry. Fortunately, you can quickly resolve this issue — turn on your shower and let the water run for a few minutes to refill the P-trap. The water will rehydrate the P-trap and help stop sewage gases from leaking into the bathroom. Pour a quart of water into every drain throughout your home, including the toilet and sink, if you still notice the smell.

Persistent odors could be the sign of a leaky or old P-trap. To be sure, reach out to a professional plumber to examine and replace your P-trap.

4. Leaking Pipes

Leaky pipes under your shower or in the bathroom walls can also cause a sewage smell. Leaking pipes allow hydrogen sulfide to escape, causing a sewer odor. Loose-fitting piping and perforations can cause leaks, and some perforations are caused by corrosion in certain metal pipes. Clogs that contain strong chemicals can also cause corrosion and perforations if they sit in your pipes long enough.

How to fix the problem: If your house is new or recently renovated, poor installation could be the cause of loose pipe fittings. If you believe that a leaking pipe is the cause of your bathroom's sewage odor, it is best to contact a plumber for assistance. A leaky pipe can indicate more serious plumbing issues, and the solution for fixing a leaky pipe depends on various factors such as the pipe material and accessibility.

Odors From Your Toilet

If your bathroom smells like sewage, the odor may be coming from the toilet. Typically, you can fix a bad-smelling toilet with a quick clean, a few flushes and some air freshener. However, sometimes a smell will not go away, no matter how many times you clean your bathroom. A sewer gas smell from your toilet can indicate a serious plumbing issue.

Many potential factors can cause a bathroom to smell like a sewer. Among the more common reasons for a sewer gas smell in the bathroom are an incorrectly installed or cut vent pipe, a broken or loose seal or a septic blockage.

1. Improperly Installed or Cut Vent Pipe

If there is a septic smell in your bathroom from the walls near your toilet, the cause could be an improperly installed or cut vent pipe.

The vent pipe helps regulate the air pressure in your home's plumbing system. Vent pipes also redirect odors outside your home so they do not leak into your home or bathroom. However, sometimes contractors install vent pipes improperly, which can cause them to send odors into your bathroom.

How to fix the problem: A professional plumber can help you solve any problems with a vent pipe. In cases involving a poor installation, an experienced plumber can quickly diagnose the problem and reinstall a new pipe.

Sometimes, a vent pipe will develop cracks that allow odors to spill out into your home. To find any cracks, a plumber will use a smoke machine to fill the pipe. Once the smoke begins to emerge, they will trace it to the source of the leak and repair the pipe.

2. Broken or Loose Seal

If your toilet smells like sewer, it could have a broken or loose seal.

The toilet attaches to the drain through two different seals. If these seals are loose, broken or improperly installed, they could allow sewer gasses to enter your bathroom. One indication of a broken seal is if the toilet bowl does not fill up normally.

If a seal leaks water and sewage, a bad smell might not stem from sewage gasses. Sometimes, water will pool in crevices in and around your toilet, attracting bacteria. As the bacteria grow, they produce a foul odor.

Sometimes a toilet leaks from the wax ring, which seals the toilet drain and prevents water leakage. If the toilet bowl is loose, it can damage the wax ring, leading to sewage seeping out and producing bad smells.

Your toilet could also be broken, cracked or otherwise damaged. For example, it may have cracked around the bolts that fasten it to the floor or from using a drain snake too aggressively. Even small cracks can let sewer gas seep into your bathroom.

How to fix the problem: If the problem is a broken or loose seal, often a fresh application of caulk is enough to fix the issue. Apply caulk to your toilet's seals, as well as the bolt holes securing the toilet to the ground.

Check to see if your toilet bowl is wobbly or loose — if it is, it may have broken the wax ring. To repair it, reset the toilet with a new toilet ring.

If the toilet itself appears to have broken, contact a professional plumbing service for repairs.

3. Septic Blockage

Flushing certain things down the toilet can cause septic blockage. Even if a product, such as baby wipes, is labeled as “flushable,” it can cause a blockage in your septic system, which can lead to odor.

How to fix the problem: Avoid flushing anything other than waste and toilet paper down your toilet to prevent this issue. Use a plunger to bring already flushed wipes and materials back up to remove them. A drain snake can reach items that went farther down the pipe.

Odors From Your Sink

Sometimes, a sulfur-like smell comes from your bathroom or kitchen sink.

If your kitchen or bathroom sink smells like sewage, there are a couple of things that could be causing it. Just like a shower drain, it could have a dry P-trap. However, another common source of odors is buildup in the overflow.

1. Buildup in the Overflow

If you notice a sewer smell in your bathroom sink, check to see if it has an overflow mechanism.

Many sinks come with a hole near the top designed to provide an outlet for water, preventing overflows from spilling into the bathroom. Like anything near water, your sink can build up grime and mildew quickly, especially in the overflow area.

How to fix the problem: Fortunately, cleaning the overflow is an easy project. All you need is water, bleach and a small bottle brush:

  1. Use a small bottle brush to scrub the interior of the overflow area and remove any debris.

  2. Next, mix a solution of half water and half chlorine bleach.

  3. Apply the solution to the overflow area with the bottle brush to eliminate any lingering bacteria or odors.

If the odors do not go away after a thorough cleaning, contact a professional plumbing service to examine your sink.

Odors From Your Washing Machine

When you notice your house smells like sewage, the first place you look is probably the bathroom. If that is not the source of the smell, the cause may be in your laundry room.

If your house smells like sewer when you are doing laundry, the washing machine is most likely the culprit. Common causes of a sewage smell in a washing machine include incorrectly installed P-traps and clogs in the drain or vent.

1. Improperly Installed P-Trap

P-traps are not just for your bathroom — they are essential for washing machines, too. However, unlike many bathroom pipes, modern washing machines come with a flexible drain hose. The wastewater from a washing machine flows through this flexible hose into the drain box pipe, which connects to the P-trap.

Because the hose is flexible, it can easily be improperly installed. The hose may have been inserted too far into the drainage box, which prevents the P-trap from functioning. As a result, odors can seep into your home.

How to fix the problem: To solve this problem, try pulling the washing machine drain hose out of the drain box. Stop when the hose is roughly eight inches deep in the piping — this will let the P-trap work properly, keeping sewer gasses from leaking into the room.

2. Drain Clogs

Another common reason for a bad-smelling washing machine is a clog in the drain pipe. If your washing machine drain smells like sewage, it may be clogged.

A clog in the drain line will create a buildup of organic matter like hair and soap. Bacteria grows on the drain clog, developing an unpleasant sewage-like odor. If left untreated, a clog will build on itself, growing larger and larger and producing more noticeable odors.

How to fix the problem: Fortunately, a clogged drain has an easy fix. Using a drain snake, clear out any clogs in the drain line. If the clog refuses to budge, contact a professional plumber to take a look at your drain and washing machine.

3. Vent Pipe Clogs

As with your bathroom plumbing, washing machines need vent pipes. All drain systems in your house must be properly vented to prevent sewage gasses from seeping into your home.

A clogged vent pipe can prevent sewer-smelling air from leaving your home. This situation often results in leaking odors, and they typically come from the walls around the vent pipe.

How to fix the problem: To check for clogs in your vent pipes, you have to access your roof. Bring a flashlight and shine a beam into the vent pipes. Search for any obstructions, such as bird nests or other debris. Using a snake or another long tool, try to dislodge or remove them.

For the best results, work with a plumber to address the issue — professional plumbers have the knowledge and tools to safely and quickly remove clogs from vent pipes.

Odors From Your Water

If you notice a sulfur-like smell when you turn on the tap, the problem may go deeper than a clogged drain. Before assuming your water is the problem, try a few troubleshooting measures.

Use a de-clogging solution to eliminate any buildup in the pipes. After you've given the cleaning material time to work, pour a glass of water down the drain and walk away from the sink. Smell the water — if it still has an odor, you might have bacteria in your water heater, or your water might contain hydrogen sulfide.

1. Bacteria in Your Water Heater

If the smell is only noticeable when you use hot water, the problem is most likely with your water heater.

Occasionally, bacteria colonies can establish themselves in a water heater if the temperature of your heater is too low or if you leave it turned off for long periods. Fortunately, the bacteria should not be harmful to humans, so your health is not in danger. However, the bacteria produce a strong rotten egg smell in the house, which reduces your ability to enjoy your water.

How to fix the problem: If bacteria are thriving in your water heater, you can try increasing the temperature of your heater for up to 24 hours. Run the hot water taps to flush out the pipes of any remaining bacteria.

Remember to proceed carefully if you decide to turn up the temperature of your water heater — it is easy to forget your water is hotter than average, which can lead to burns.

2. Hydrogen Sulfide in Your Water

If your water smells bad regardless if it is hot or cold, the problem might lie in your water source. Highly concentrated amounts of hydrogen sulfide produce a strong sulfur smell in the house.

Although hydrogen sulfide can be toxic in large amounts, it is usually easy to detect before it reaches harmful levels. Humans can detect the presence of hydrogen sulfide as low as .5 parts per million (PPM) — levels less than 1 PPM will produce a musty scent, and levels between 1 and 2 PPM will have an odor similar to rotten eggs.

How to fix the problem: If you suspect your water source may contain hydrogen sulfide, contact your local water testing lab to have your water examined for contaminants.

Odors From Other Areas

You might notice a sewage smell in your yard or basement not directly near a bathroom or laundry room caused by an issue with your home's cleanout.

1. Missing Cleanout Plug

Cleanout plugs are meant to cap cleanout lines, which are the main sewer line access points located in your yard. In colder climates, the cleanout is usually inside the garage, a utility room or near a bathroom. Slab homes and those in warmer climates usually have an outdoor cleanout. A cleanout plug may allow gas to leak into the house if a cap is broken or missing.

How to fix the problem: To fix this issue, you can purchase a replacement plug from a hardware store. You can also contact a plumber to replace a missing or broken cleanout plug.

How to Get Rid of a Sewer Smell After You Eliminate the Source of the Odor

When you resolve the issue causing sewage gas to leak into your home, the gas will stop entering your house, but an odor may continue to linger. If a sewage odor was leaking into your house for an extended amount of time, it may leave an unpleasant trace because odors can hang in the air and cling to fabric surfaces.

The most important step in removing sewage odors from your home is fixing the source of the odor. Once you complete this step, there are some things you can do to freshen your home and make it smell pleasant again. To completely remove the sewage odor from your living space, consider the following tips:

Let in Some Fresh Air

Open all the windows around your house. The ventilation will help to remove the odor from your home's air, and the fresh air from outside will be a refreshing relief from the odor. If it's raining or cold outside, try to leave your windows open just a crack, or open them for short intervals to help circulate the air.

You can also freshen the air in your home with charcoal. Place some pieces of charcoal into several small bowls, and set them throughout your home. The charcoal pieces will absorb the sewage odor and help to eliminate it from the air.

Remove the Odor From Your Carpet

Any carpeted floors in your home may have absorbed the sewage odor. You can neutralize the odor with baking soda. To remove the sewage odor from your carpets, simply sprinkle baking soda onto each carpeted surface. Leave it on the carpets overnight and thoroughly vacuum it in the morning.

Neutralize Your Furniture and Soft Surfaces

Similar to your carpeted surfaces, the sewage smell may also cling to any fabric, such as on your couches and chairs. Throw washable items like throw blankets or small cushions into the washing machine. For larger items you cannot wash, use undiluted white vinegar to neutralize the smell.

Pour some white vinegar into a spray bottle and hold it six inches away from surfaces as you spritz them. The vinegar will eliminate the sewage odor, and the vinegar odor will eventually fade until your home smells fresh and clean. Be sure to spot-test the vinegar in a hidden area on your furniture to ensure it does not stain the material.

When You Need a Plumber

Many sources of sewage smells are easy to fix at home. However, if you ever feel uncomfortable repairing a plumbing issue, do not hesitate to contact a plumbing service — professionals can quickly and efficiently solve your plumbing problems.

Some problems are beyond the expertise of the average homeowner. One issue in particular typically requires the knowledge of a plumber: a sewer backup.

The most obvious sign of a sewage backup is overflowing drains. If your shower and toilet drains suddenly begin to gurgle with rancid water, you are most likely dealing with a major sewage problem.

Sewage backup often results from large-scale events such as floods, tree roots or pipe damage. Here are a few of the most common issues behind a backed-up sewer:

  • Blockages in a sanitary main: Sometimes, blockages from debris gradually accumulate in the city sanitary main. Over time, these blockages can lead to sewage seeping up through your basement or bathroom drains.

  • Tree root invasion: Trees or shrubs can send roots deep into the earth in search of water. Sometimes, these strong roots can crack sewer lines and cause sewage to leak out. In severe cases, the roots can create blockages in the main lines, leading to backed-up sewage.

  • Broken or collapsed sewer lines: If you live in an older home or neighborhood, your sewage backup could be the result of cracked, broken or collapsed sewer lines.

  • Flooding: The surge of water from floods can force sewage up through drain pipes and into your home.

  • Freezing: A septic system can freeze and become clogged with ice when you don't use it for a period of time or if it is not properly insulated. You can help prevent this by placing mulch over your system. If ice does back up your system, a plumber can determine where the ice is located.

In situations like this, your first action is to call an emergency plumber. They will be able to assess the situation and determine whether the issue is coming from tree roots or the city sewage system.

Work With a Team You Can Trust

A sewer smell in your house is serious and should be addressed as soon as possible. When you have a plumbing emergency, work with a team you can trust.

Whether you are dealing with a failing water heater or a smelly laundry room, the professional team at Mr. Rooter Plumbing of Greater Syracuse is here to help. For almost five decades, Mr. Rooter Plumbing has been the nation's most trusted provider of plumbing and repairs. With fair, upfront pricing estimates and no hidden overtime charges, we are dedicated to providing the highest possible level of customer service.

For plumbing and repairs, or to troubleshoot a stubborn sewage smell, contact Mr. Rooter Plumbing of Greater Syracuse today.