Sewer gas: symptoms & dangers of long-term hydrogen sulfide exposure making you sick

Depending on its source, sewer gas can be toxic or non-toxic. Either way, there is still the inconvenience of having such a bad smell in your house. This gas is formed during the decay of the waste, releasing high concentrations of hydrogen sulfide and ammonia.

This gas can enter your home through vents or floor drains. Once you notice the bad smell, it is important to take immediate action, as your health might be at risk. Continue reading this article as we talk about sewer gas. We will cover the symptoms and dangers of long-term hydrogen sulfide exposure that can make you sick.


The most common symptoms of sewer gas are coughing and lightheadedness. The most common dangers of long-term hydrogen sulfide exposure include falling sick, having seizures, and lung irritation.

In this article, we’ll also take a look at the following topics:

  • The best test methods
  • The causes for it in your home

Table of Contents

What is sewer gas?

Natural human waste will undergo a decaying period in which several toxic chemicals are eliminated in the air. The result is sewer gas, a byproduct of this process. It contains ammonia and hydrogen sulfide, which are dangerous for humans during longer periods of exposure.

This gas can be considered harmless at low levels, and the only inconvenience will be the bad smell. But higher exposure for a long time will cause several symptoms that suggest intoxication with sewer gas. The main culprit is hydrogen sulfide, which also gives that specific smell of rotten eggs. 

Early symptomsLong-term symptoms
Eye irritationLoss of smell
CoughingLung irritation
Poor concentration

What does hydrogen sulfide smell like?

sewer runoff

Household and industrial waste will release hydrogen sulfide upon decaying. This smell is similar to one of the rotten eggs, which can be quite irritable even at low concentrations. While the discomfort is not dangerous, there is also the risk of explosion as raw sewer gas can be highly flammable.

Hydrogen sulfide occurs naturally in volcanoes, sewers, and oil wells. All of these environments are dangerous and require protective equipment. That is why you should also take the necessary action to remove this smell as soon as you can identify it. 

Is sewer gas dangerous & can it make you sick?

There are 3 main dangers of sewer gas exposure. From health risks to fire hazards, these scenarios should not be ignored. Firstly, hydrogen sulfide poisoning occurs as you get exposed to low levels of this gas. You will notice several symptoms when you breathe, such as nausea and headache. 

Some people can experience dizziness and irritation of their respiratory tract. In some extreme cases, when the concentration of hydrogen sulfide is high, it can cause loss of consciousness and even death. The other risk is represented by asphyxiation. Sewer gas also releases methane which can cause suffocation when it is present in enclosed areas.

Lastly, be advised that this gas is also highly flammable, and there is always a risk of explosion and fire. Both hydrogen sulfide and methane are highly flammable gases. 

Symptoms of sewer gas poisoning

Once exposed to this toxic gas, the first reaction will be discomfort as your sense of smell is greatly disturbed by the bad smell. But suppose you continue to breathe in the sewer gas. In that case, you will experience additional symptoms that indicate your health might be at risk. 

The most common symptoms of sewer gas poisoning include:

  • Eye irritation
  • Lightheadedness
  • Fatigue
  • Coughing
  • Poor concentration
  • Nausea

These are among the first symptoms you will experience upon prolonged exposure to hydrogen sulfide. They are good warning signs for leaving the environment to prevent worse symptoms from appearing. If you continue to be exposed to sewer gas, you might experience the following:

  • Loss of smell
  • Seizures
  • Coma
  • Lung irritation

Is there a sewer gas poisoning blood test?

men looking into the sewer

Medicine is quite advanced in today’s age, and treatment is more effective than it was hundreds of years ago. But we are still far from curing illness permanently or reversing the aging process. With sewer gas poisoning, a couple of standards have been developed.

Unfortunately, no blood test can determine whether you were exposed to sewer gas or not. While there is no certain way to find out, you can assume this poisoning if you’re experiencing the symptoms related to sewer gas exposure. 

Best sewer gas leak detectors

While bad smells and specific symptoms are enough to inform you about a sewer gas leak, you still need to pinpoint the exact location to repair the pipe. For maximum accuracy, a couple of tools are designed for this purpose. Take a look at the best one currently available on the market.

Y201 Propane and Natural Gas Leak Detector

With this performant tool, you can pinpoint the location of any leak that is affecting your home. All you have to do is run the sensor probe along the pipe to locate the exact leak. The device will inform you through various alarm sounds and an LED night whenever it finds a possible leak.

Operating this tool is easy, and you won’t have to pay an engineer to do this work for you. A sensitivity dial allows you to calibrate the device according to your needs. As you start the device, allow up to 10 seconds before operation until the yellow warm-up light turns off. 

This product easily delivers maximum performance with more than 5,000 satisfied customers worldwide. After reading the instructions, you can use it for various purposes, including identifying the sewer gas leak. 

NameY201 Propane and Natural Gas Leak Detector
Detection Range0.1% – 40% LEL, minimum 50 ppm
Power Source3 AAA batteries
Response Time≤ 2 seconds
Warm up Time10 seconds


  • Cheaper than getting a professional to come out.
  • The sensibility tester works great.
  • It provides great protection after an earthquake, allowing you to see if anything’s leaking.
  • Easy to use


  • Batteries are not included.
Y201 Leak Detector
8,226 Reviews
Y201 Leak Detector
Here's a cheap leak detector you can get.

Long-term exposure to sewer gas

Exposure to hydrogen sulfide for a long time will affect several systems of your body. Low concentrations will only cause irritation of the eyes and discomfort, symptoms that should go away on their own after a few weeks. 

But if the concentrations are high, the environment is dangerous, and the air is no longer breathable. It only takes a few breaths for severe symptoms, such as loss of consciousness or even death. While a residential home cannot reach such intense concentrations of hydrogen sulfide, some workplaces can. 

Can sewer gas kill you?

Low concentrations of sewer gases will not produce life-threatening effects on the body. However, this gas becomes toxic to humans in large amounts. The primary substance is hydrogen sulfide which can damage several systems in your body. If your house smells bad at night, take immediate action and protect yourself.

Ammonia also contributes to its deadly effect. It is a compound used in cleaning products and has a specific color. When you are exposed to this chemical, you will experience mild irritation. At higher levels, ammonia becomes toxic, and it will cause organ damage or even death

Sewer gas poisoning treatment: how to get rid of hydrogen sulfide in your body

man in the sewer

Currently, there is no treatment or antidote for hydrogen sulfide poisoning. If inhaled in small amounts, this substance will not cause significant damage to your body, and you will heal over time. The immune system is strong and knows how to recover after such a situation.

But for severe cases of sewer gas poisoning, there are some possible solutions. Doctors recommend nitrite therapy, but you should not take it on your own. Seek urgent medical assistance after prolonged exposure to hydrogen sulfide, and a doctor will help you with this problem. 

The sewage smell in the house comes and goes.

You can notice the sewage smell coming and going into your house for several reasons. Clogged drains could be responsible for this situation which is also the most common one for people that experience this smell.

When the wastewater has nowhere to go, it will come back up the drain and cause this uncomfortable smell. Check the bathtub and look for any water coming up from the sewer. It clearly indicates clogged drains, and you might have to call a plumber for this situation. 

There’s a rotten egg smell outside.

If you can smell rotten eggs, it is likely hydrogen sulfide. The smell is the same and uncomfortable for everyone. It is a clear indication that this substance comes from waste. If you smell rotten eggs outside, then you can easily confirm the presence of this gas.

It might come from malfunctioning sewerage systems. There is something broken in the neighborhood sewage system, so you should call the plumbers. They can locate the problem with performant tools and fix it quickly. Immediate action is necessary because hydrogen sulfide is toxic to humans. 

What causes a sewer smell in the house?

The bad smell does not appear without reason, and the cause is very easy to identify. Most likely, there is a weak link in the plumbing system. It is true, especially if you can pinpoint the source of your bathroom. The sink drains or the toilet are responsible for this situation.

Clogged drains are among the most common cause of sewage smells in residential buildings. If you experience the same, call the plumbing company and request their professional help. They will assist you, and the problem can be solved quickly. 

hydrogen sulfide

How to get the sewer smell out of the house?

If you can smell sewer gas, you can do a couple of things to get rid of this unpleasant odor. You can also suffer several health problems from this smell, so getting rid of it as soon as possible is important. Start by opening all the windows in your house to let the smell out. 

It will also allow the air to circulate more freely, and the bad odor will be replaced by fresh air from outside. Another solution implies charcoal pieces placed into a small bowl. This material is ideal for absorbing smells and keeping the air fresh. 

Charcoal bags

Here are the charcoal bags we recommend to get rid of the odor.

NameBamboo Charcoal Bags Odor Absorber
What we loveEasy hanging with hooks


  • Great product
  • Very effective at getting rid of unpleasant smells.
  • Great value


  • You still want to get rid of the source of the smell.
  • Won’t work if the source of the smell is strong and continuous.
  • Some received
Charcoal bags
7,141 Reviews
Charcoal bags
They really work.

Does sewer gas rise or fall?

Because it contains hydrogen sulfide and ammonia, the sewage gas is heavy. It will sink to the lowest level in the room. Because it is situated at the floor level, it is harder to ensure a constant flow, so that the smell might be stagnant.

There are a couple of solutions to get rid of this smell, as we recommended before. But if you find yourself in a life-threatening situation with extreme concentrations of sewer gas, always keep your head at a high level and breathe near the ceiling if possible. 

sewer gas


Is sewer gas harmful to your health?

In low concentrations, sewer gas is not harmful to your health. It can cause mild discomfort, and your eyes and mouth might feel irritated. This horrible smell will also disturb your nose, but your well-being is not at risk.

However, exposure to a higher sewer gas concentration is dangerous for your health. While such extreme levels are not encountered in residential areas, some waste processing plants will have them. The workers are equipped with protective equipment that ensures clean air for breathing. 

Can sewer gas cause headaches?

A headache is usually among the first symptoms experienced by people exposed to sewer gas. Hydrogen sulfide gas is harmful and toxic for humans, but it will only cause mild symptoms in small amounts. If you inhale it, you might suffer from dizziness, headache, and nausea.

Do not underestimate the seriousness of this gas. Most people are only taking into consideration the bad smells. Still, some serious health risks appear with prolonged exposure to hydrogen sulfide. Change your environment or ensure proper ventilation once you notice this smell. 

Is sewer gas explosive or flammable?

While there are health risks involved, your safety is also in danger when you are in an environment with high concentrations of sewer gas. When this smell comes from outside, it will be most concentrated in the place where it enters your home. 

It can also accumulate in basements as they are poorly ventilated. Sewer gases contain methane and hydrogen sulfide. Both of them are highly flammable and explosive. Once exposed to a strong heat source, this gas can light up and even explode when it accumulates in high amounts. 

If you notice this smell inside your house, do not turn on the lights or any other appliance. A single spark could set the atmosphere on fire. Seek the help of plumbing companies that will also help you remove this gas from your home. 

Is sewer gas heavier than air?

Sewer gas is made of many components, most of which are heavier than air. That is why it will accumulate at lower levels of structures, including basements. Methane is the only less dense component than air and will rise through the atmosphere.

That is why you are able to notice the unpleasant smell everywhere in a room. While the high concentration is located at the floor level, methane brings this smell upwards, and you will be able to sense this toxic gas. If you notice it inside your house, your basement will most likely have a higher concentration.

If there is more sewer gas in the basement, do not attempt to go there without protective equipment. Beware of the explosion risk, and do not turn on the lights when you enter the basement. 

Is a sewage smell in the bathroom, basement, or house dangerous?

This smell is dangerous to your health because it contains methane and bacteria that is toxic to your body. But if you notice bad odors in the bathroom, you should not worry about your health. Most likely, the concentration is very low, and your nose experiences the only inconvenience. 

When this smell is constant throughout the entire house, and you feel dizzy and nauseous, it might be a sign of higher concentrations, and your health is at risk. Evacuate the building immediately and ask the plumbing company for help. They have professional tools and can eliminate this toxic gas from any interior space.