Sewer gas is a mixture of toxic and nontoxic gasses from decomposing waste materials in our sewer lines. It includes an assortment of gasses such as methane, hydrogen sulfide, nitrogen oxides, sulfur dioxide, carbon dioxide, and ammonia.

And you can easily know that you have a sewer gas problem in your house if you can smell a distinct odor of rotten eggs.

Symptoms of Sewer Gas Poisoning

Sewer gas doesn’t result in poisoning at low levels, but is dangerous at higher levels. Whereas most people will experience mild symptoms, others might not be lucky and have difficulty breathing. In such a case, contact relevant medical emergency services for help, as unconsciousness may lead to death.

Consequently, look out for the following symptoms of mild sewer gas poisoning.

  • Nausea or vomiting
  • Headaches
  • Fatigue
  • Lightheadedness
  • Poor memory and concentration
  • Coughing and shortness of breath
  • Eye irritation

For your information, it’s rare to be exposed to high levels of sewer gas in our homes. On the contrary, people working in industries may experience high levels of sewer gas exposure. If you work in such an environment, look out for these additional symptoms:

  • Mouth, throat, and lung irritation
  • Seizures
  • Coma
  • Loss of smell
  • Death in extreme cases

It can be challenging determining sewer gas poisoning solely from the symptoms above. Therefore, the smell of rotten eggs indicates the presence of hydrogen sulfide and sewer gas.

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How Does Sewer Gas Get in your House?

There are a few ways sewer gas can enter your home and linger.

  1. Blocked vents and drains. Blocked vents and drains are some of the biggest contributors to sewer gas exposure. Sewage gas is intended to escape through vents in your home’s roof. When those are blocked, the gas can build up in your home instead. It’s as simple as that.
  2. Dry floor drains. If you have a floor drain in your garage, basement, or yard, it’s important that it actually drains water every once in a while. Without some regular use, the water in your drain can evaporate, clearing the way for gas to work its way up the pipe.
  3. Improper plumbing equipment installation. If your toilets, sinks, floor drains, and other fixtures weren’t properly installed or sealed, that can also contribute to sewer gas buildup. One of the biggest culprits is the wax ring that belongs under your toilet: without it, your drain line can easily leak gas.
A ground drain: a common source of sewer gas

What Are the Health Effects of Exposure to Sewer Gas?

There are several symptoms of sewer gas poisoning and overexposure that can manifest. Sewer gas is dangerous under any circumstances, but in high enough concentrations it can be literally fatal.

Hydrogen Sulfide Poisoning

Low levels of hydrogen sulfide exposure results in coughing, shortness of breath, and irritation of the eyes, throat, nose, and respiratory system. Additionally, exposure to moderate concentrations causes headaches, nausea, vomiting, and dizziness.

Exposure to high levels is dangerous and can result in immediate loss of consciousness and death.

Asphyxiation

When sewer gas leaks into the house, methane quickly replaces the oxygen in the air, leading to suffocation. Consequently, you’ll experience symptoms related to lack of oxygen, such as dizziness, headache, nausea, and unconsciousness.

At higher sewer gas levels or low oxygen concentration (less than 12%), exposure to methane gas may lead to death without warning. Yes, sewer gas can kill you in your sleep.

Explosion and Fire

Hydrogen sulfide and methane are flammable and explosive components of sewer gas. Furthermore, you’re in danger as leaked vapors from poorly disposed of fuels in the sewer lines increase the fire risk.

Rotten Eggs Odor

Unlike other toxic gasses, sewer gas has a distinct rotten egg smell that quickly alerts the homeowner of a leak. Neglecting the smell is costly, as hydrogen sulfide paralyzes the olfactory nerve at 100 ppm (parts per million), removing a victim’s sense of smell.

What Should You Do Upon Suspecting Sewer Gas Poisoning?

The seriousness of effects of sewer gas poisoning varies from person to person, as it depends on:

  • A person’s habit, such as smoking
  • Previous exposure to chemicals and medicine
  • Individuals’ health
  • Length of sewer gas exposure
  • And levels of sewer gas exposure

As a result, never neglect any level of sewer gas exposure. Whether you smell sewage when you do laundry or throughout your home at night, know that it’s more than an inconvenience. It’s a health hazard.

Upon suspecting a leak, evacuate the area immediately and seek out medical attention. Also, put off all fires and avoid creating ignitions or sparks from any appliance, matchbox, or cigarette lighters. Sewer gas is highly flammable, and the last thing you want to do is add a house fire or explosion to the exposure risk.

Yes, several common household items and issues can contribute to sewer gas buildup. These include:

  1. Clogged Drains: Accumulation of food debris, grease, hair, soap scum, or other organic matter in drains can create blockages that cause sewer gases to back up into the home.
  2. Dry P-Traps: The P-trap is a plumbing fixture that holds water to prevent sewer gases from entering the home. If a drain is rarely used (like in guest bathrooms or infrequently used sinks), the water in the P-trap may evaporate, allowing sewer gases to escape into the air.
  3. Leaky Sewer Pipes: Cracks or leaks in sewer pipes can allow sewer gas to escape into the home. This can be particularly problematic if the pipes are located under floors or within walls where the leaks aren’t easily visible.
  4. Blocked or Broken Vent Pipes: Plumbing systems have vent pipes to release gases from the sewer. If these pipes become blocked (by debris, bird nests, or even tree roots) or are damaged, it can cause sewer gases to enter the living space.
  5. Chemical Drain Cleaners: While these are designed to clear blockages, some harsh chemicals in drain cleaners can break down organic matter in the pipes, which could inadvertently release more sewer gases. They may also corrode pipes over time, leading to leaks.
  6. Improperly Installed or Damaged Toilet Seals: If the wax ring seal around a toilet is broken or improperly installed, it can allow sewer gas to leak into the home.
  7. Sump Pumps and Floor Drains: If a sump pump or floor drain isn’t properly maintained or has a dry trap, it can become a pathway for sewer gas to enter the home.
  8. Grease or Food Waste in Garbage Disposals: Excess grease or food waste that isn’t properly ground in a garbage disposal can clog the system, leading to odors and gas buildup.
  9. Bathtubs, Showers, and Sinks with Infrequent Use: As mentioned with dry P-traps, drains that aren’t used regularly can result in sewer gas buildup due to the evaporation of the water seal in the trap.
  10. Improperly Sealed Basement Drains: Basement drains that aren’t sealed correctly can allow sewer gases to leak into the basement and then spread throughout the home.

If you suspect sewer gas buildup in your home, it’s important to have your plumbing system checked by a professional to identify and fix any potential issues. Regular maintenance can prevent many of these problems from occurring.

A malfunctioning plumbing system can play a significant role in sewer gas exposure by allowing these gases to leak into the living spaces of a home or building. Here are some ways in which plumbing system issues contribute to sewer gas exposure:

  1. Broken or Leaking Sewer Pipes: Cracked, damaged, or deteriorating sewer pipes can allow sewer gases to escape from the plumbing system and enter the home. This is especially a concern if the pipes are hidden in walls, under floors, or outside the home, where the leaks are difficult to detect.
  2. Dry or Empty P-Traps: The P-trap is a curved section of pipe beneath sinks, bathtubs, and toilets designed to hold water, creating a barrier that prevents sewer gases from traveling back into the home. If a drain is infrequently used, the water in the P-trap can evaporate, allowing sewer gases to escape into the air. Malfunctioning or improperly installed P-traps can also fail to maintain this seal.
  3. Blocked Vent Pipes: Vent pipes are part of the plumbing system that allows gases to escape from the sewer line and prevents the buildup of pressure in the pipes. If these vent pipes become clogged or damaged (e.g., by debris, tree roots, or ice), sewer gases may not be vented properly and can instead leak into the living spaces. This can lead to dangerous levels of exposure.
  4. Incorrectly Installed Fixtures: Poorly installed plumbing fixtures, such as toilets, sinks, or bathtubs, can cause leaks around seals and joints, allowing sewer gas to seep through the gaps. For example, an improperly sealed toilet can allow sewer gases to escape from the base, creating an unpleasant and hazardous environment.
  5. Clogs and Blockages: Serious blockages in the sewer lines (due to grease buildup, tree roots, or other debris) can cause a backup of waste and sewer gases into the plumbing system. If this happens, the gases may find their way into the home through drains or toilets, particularly if the clog causes a backup in the venting system as well.
  6. Sump Pump or Floor Drain Issues: Sump pumps or floor drains are designed to remove water from basements or lower areas of a building. If these systems become malfunctioning or clogged, they can lead to stagnant water and, in some cases, sewer gas buildup. If the water level is too low or the trap is dry, sewer gases can enter the living area.
  7. Sewer Line Backups: When a sewer line becomes completely blocked or backed up, it can result in wastewater and sewer gases backing up into the house. This is a severe issue that can contaminate the air and make living spaces unsafe.

In all of these cases, the malfunctioning plumbing system fails to prevent sewer gases from escaping into the home, leading to exposure. This exposure can result in foul odors and, in some cases, health risks such as nausea, headaches, dizziness, and even more severe symptoms with prolonged exposure (e.g., hydrogen sulfide exposure). Regular maintenance and timely repairs of the plumbing system are crucial to preventing sewer gas exposure.

Yes, sewer gas poisoning can occur without a noticeable smell, though it’s less common. Sewer gas primarily contains a mixture of gases like methane, hydrogen sulfide, ammonia, and carbon dioxide, many of which are odorless or have very faint odors. Here are a few reasons why sewer gas poisoning might occur without a strong smell:

  1. Low Concentrations of Hydrogen Sulfide: Hydrogen sulfide, which gives sewer gas its characteristic “rotten egg” odor, may be present in low concentrations that are not easily detectable. Even at low levels, exposure to hydrogen sulfide over time can still cause symptoms of poisoning, such as headaches, dizziness, and nausea.
  2. Ventilation Issues: In some cases, sewer gases can be vented away from the home or building in a way that prevents the typical smell from being noticeable indoors. However, if there is a malfunction in the venting system or if gases accumulate in a closed area, they could still pose a health risk without being easily smelled.
  3. Ammonia and Carbon Dioxide: Ammonia and carbon dioxide, other components of sewer gas, are either odorless or have a very faint smell. Ammonia may be present in concentrations that do not produce a strong odor but can still cause irritation to the respiratory system. Carbon dioxide, while not harmful at low concentrations, can displace oxygen in enclosed spaces, potentially leading to symptoms of poisoning.
  4. Sensitivity Variability: Not everyone may be able to smell sewer gas, especially if it’s diluted or if the person has a reduced sense of smell. Prolonged exposure to low levels of sewer gas can lead to poisoning even without a noticeable odor.
  5. Slow Gas Build-up: In some situations, sewer gas might leak slowly over time without creating a noticeable odor but could still lead to elevated levels of exposure, especially in poorly ventilated areas like basements or crawl spaces.

While the smell is a common indicator of sewer gas presence, it’s important to be aware that health symptoms associated with sewer gas poisoning (such as dizziness, headaches, nausea, eye irritation, and fatigue) can still occur in the absence of a noticeable odor. If you suspect sewer gas exposure, it’s critical to address potential plumbing issues promptly and consider air quality testing to detect dangerous gas levels.

Long-term exposure to sewer gas can lead to a variety of health problems, particularly if the exposure occurs over extended periods of time in poorly ventilated areas. While the immediate effects of sewer gas exposure (such as nausea, dizziness, and headaches) are often temporary, prolonged exposure can cause more serious and lasting health issues. Some of the potential long-term effects include:

1. Respiratory Problems

  • Chronic Respiratory Irritation: Continuous exposure to sewer gas, particularly ammonia and hydrogen sulfide, can irritate the lungs and airways, leading to chronic coughing, wheezing, and shortness of breath.
  • Asthma and Bronchitis: People with pre-existing respiratory conditions, such as asthma, may experience aggravated symptoms, leading to increased attacks or the development of chronic bronchitis over time.

2. Neurological Effects

  • Cognitive Impairment: Prolonged exposure to certain gases like hydrogen sulfide may affect the nervous system, leading to cognitive issues such as memory problems, difficulty concentrating, and confusion.
  • Headaches and Migraines: Long-term exposure to low levels of sewer gas can trigger persistent headaches and migraines, especially in individuals who are sensitive to environmental pollutants.

3. Cardiovascular Issues

  • Increased Blood Pressure: Chronic exposure to high concentrations of hydrogen sulfide has been linked to an increase in blood pressure and heart rate, which can strain the cardiovascular system.
  • Heart Palpitations: Some individuals may experience irregular heartbeats or palpitations due to the stress placed on the cardiovascular system from prolonged exposure to sewer gases.

4. Chronic Fatigue

  • Persistent Fatigue: Long-term exposure to sewer gases can lead to ongoing tiredness and general fatigue, as the body’s systems are continuously stressed by the toxic effects of the gases.

5. Liver and Kidney Damage

  • Toxic Accumulation: Certain compounds in sewer gas, like hydrogen sulfide, can have toxic effects on the liver and kidneys if exposure is prolonged. These organs are responsible for filtering out harmful substances, and continuous exposure to sewer gases could cause them to become overburdened, leading to potential damage or dysfunction.

6. Eye and Skin Irritation

  • Chronic Eye Irritation: Constant exposure to sewer gas can lead to long-term eye irritation, dryness, and redness, which can result in discomfort or even damage to the cornea over time.
  • Skin Sensitivity: Prolonged exposure to ammonia and other chemicals in sewer gas can cause skin dryness, rashes, and other dermatological issues.

7. Increased Risk of Infections

  • Weakened Immune System: Exposure to sewer gas can weaken the immune system over time, making individuals more susceptible to respiratory infections, sinus infections, and other illnesses due to the strain it places on the body.

8. Increased Sensitivity to Future Exposure

  • Sensitization: Prolonged exposure to sewer gas may make the body more sensitive to future exposure, leading to more severe symptoms even with shorter periods of exposure.

9. Mental Health Issues

  • Anxiety and Depression: The stress of ongoing exposure to sewer gas, along with the potential for physical symptoms like dizziness and headaches, can contribute to mental health issues such as anxiety and depression.

10. Potential for Permanent Damage

  • Hydrogen Sulfide Poisoning: Prolonged exposure to high levels of hydrogen sulfide can cause irreversible damage to the central nervous system, potentially leading to long-term neurological impairments.

To minimize the risk of these long-term effects, it is important to address plumbing issues and eliminate sewer gas exposure as soon as possible. Proper ventilation, maintaining the plumbing system, and using safety measures to avoid exposure to toxic gases are crucial steps in protecting your health. If you suspect prolonged exposure or are experiencing symptoms, it is important to consult a healthcare professional for evaluation and treatment.

Continue Learning About Sewer Gas

Sewer gas exposure is often linked to hidden plumbing defects or damaged sewer lines.

Sources

https://www.dhs.wisconsin.gov/air/sewergas.htm

https://www.nachi.org/sewer-gases-home.htm

https://www.omegaenv.com/environmental-consulting-firm-blog/dangers-of-hydrogen-sulfide-aka-sewer-gas/