Ah, the dreaded rotten egg smell, enough to make anyone gag. Don’t let it ruin your day, we have you covered and you can soon have that awful smell gone for good. But why do drains smell like rotten eggs? In this article, we’ll look at the most likely source and what you can do to eliminate the foul odour.

Lady Holding Her Nose Because of Bad Smell

What is the Rotten Egg Smell?

The smell that comes from drains is caused by hydrogen sulphide gas, which is produced by bacteria that break down organic matter in the drain or sewer system. This gas has a distinct odour that is often compared to rotten eggs, and it’s also toxic in high concentrations.

What is Hydrogen Sulphide Gas?

Hydrogen sulphide gas is a colourless, flammable gas that has a strong smell, similar to that of rotten eggs. It is heavier than air and tends to accumulate in low-lying areas such as drains, sewers, and basements.

The gas is toxic in high concentrations and can cause respiratory problems, eye irritation, and headaches. Hydrogen sulphide gas is produced by bacteria that belong to the family of sulphate-reducing bacteria (SRB). These bacteria thrive in environments that lack oxygen, such as drains and sewage systems.

How is Hydrogen Sulphide Gas Produced?

When organic matter, such as hair, soap scum, and food particles, builds up in a drain, it creates an environment that is perfect for bacteria to grow and thrive. These bacteria break down the organic matter and produce hydrogen sulphide gas as a by-product. The gas then rises out of the drain and into the air, creating an unpleasant odour.

In addition to being produced by bacteria, hydrogen sulphide gas can also be present in the water supply.

This is particularly true if you live in an area with a high concentration of sulphur in the water. When you run water down the drain, the gas is released into the air and can create the same rotten egg smell.

How Does the Rotten Egg Smell Enter Homes?

Organic Build-up

The main cause of drain odours is bacteria build-up. Bacteria are naturally present in our plumbing systems, breaking down organic matter that passes through our pipes. However, when too much organic material accumulates in the drain or sewer line, bacteria can start to grow out of control. As these bacteria consume the organic matter, hydrogen sulphide rises from the pipes and enters the home.

Dry P-Trap

The P-trap is a curved piece of pipe located beneath sinks and other fixtures that holds water to prevent sewer gases from entering the home. If a fixture isn’t used frequently enough, the water inside the P-trap can evaporate, allowing sewer gases to enter the home through the drain. This can result in an unpleasant odour that’s similar to rotten eggs.

How to Stop Drains Smelling Like Rotten Eggs?

If you’re dealing with a foul odour coming from your drain, there are several things you can do to eliminate it.

1 – Clean the Drain

The first step in eliminating the odour is to clean the drain. You can do this by pouring a mixture of baking soda and vinegar down the drain. The chemical reaction between the two ingredients will help break down any organic matter that is causing the smell. After pouring the mixture down the drain, let it sit for at least 30 minutes before rinsing it with hot water.

Another option is to use a drain cleaner that is specifically designed to eliminate odours. These products often contain enzymes that break down organic matter and eliminate the bacteria that produce the gas.

2 – Remove any Blockages

If the odour persists after cleaning the drain, there may be a blockage in the pipe that is preventing water from flowing freely. This can cause organic matter to build up and create an environment for bacteria to grow.

To remove any blockages, you can use a plunger or a drain snake. A plunger can help dislodge any debris that is blocking the pipe, while a drain snake can reach deeper into the pipe to remove any stubborn blockages.

3 – Check the Ventilation Systems

Another possible cause of the odour is a problem with the ventilation system. If the drain isn’t properly vented, it can create a vacuum that pulls the gas out of the water and into the air.

4 – Check the Traps

If you have figured out where the smell is coming from and cannot figure out the issue, it is a good idea to check the trap of the fixture to ensure that it is working and fitted correctly.

If the trap is dry and there is no water seal, the gases can rise from the sewer system and enter the home.

5 – Call a Professional

If you’ve tried all of these methods and the smell persists, it may be time to call in a professional. A plumber can inspect your drain and sewer system to determine the root cause of the problem.

They may need to use specialised equipment, such as a camera or hydro jet, to identify and remove any blockages.

Conclusion

In conclusion, the reason your drains smell like rotten eggs is because of the production of hydrogen sulphide gas by bacteria that break down organic matter. Regular cleaning and maintenance of drains can help prevent the build-up of organic matter and reduce the likelihood of foul odours. In addition, checking the water supply for sulphur content and ensuring proper ventilation can also help mitigate the problem. Understanding the science behind the production of hydrogen sulphide gas can help homeowners take proactive steps to prevent and eliminate foul odours coming from their drains.

How to Stop Drains Smelling Like Rotten Eggs Infographic

Plumbing Wizard Tips

“If the odour is coming from the kitchen sink, check the garbage disposal for any build-up of food particles. Use a mixture of baking soda and vinegar to clean the disposal and remove any buildup!”

“Regular cleaning of the drain can help prevent the build-up of organic matter and reduce the likelihood of foul smells. Use a drain cleaner or a mixture of baking soda and vinegar to remove any build-up of organic matter!”

“Bacterial cleaners are designed to break down organic matter and can help eliminate the odour-causing bacteria in drains. They can be purchased at most home improvement stores or online!”

Frequently Asked Questions

Can hydrogen sulphide gas from a drain be dangerous?

Yes, hydrogen sulphide gas can be dangerous in high concentrations. It can cause respiratory problems, eye irritation, and headaches.

Can cleaning a drain help get rid of the rotten egg smell?

Yes, regularly cleaning and maintaining drains can help prevent the build-up of organic matter and reduce the likelihood of foul odours.

Can using bleach or other cleaning agents help eliminate the smell?

Using bleach or other cleaning agents can help eliminate the odour temporarily, but it is important to address the underlying cause of the odour, which is the build-up of organic matter and the presence of bacteria.

Can a sewer backup cause a foul smell?

Yes, a sewer backup can cause a foul odour as it releases gases from the sewer system into the building.

Can a clogged air conditioning drain line cause a foul odour?

Yes, a clogged air conditioning drain line can cause a foul smell as it allows water to accumulate in the drain, providing a breeding ground for bacteria.

Can using drain cleaners regularly cause a foul odour?

Using drain cleaners regularly can actually contribute to foul odours as it can kill off the beneficial bacteria that help break down organic matter in drains.

Can a broken or damaged sewer line cause a foul odour?

Yes, a broken or damaged sewer line can cause a foul odour as it allows gases to escape from the sewer system and into the building.


Author

Lee Pearce is not just a master plumber; he’s a veritable Plumbing Wizard. With over 30 years of experience in the trenches of pipes and drains, Lee has become the go-to sage for DIY plumbing, saving homeowners thousands in potential call-out charges. As the founder of Plumbing Wizard, he’s dedicated to demystifying the complexities of home plumbing, offering easy-to-follow advice that stands the test of time and pressure. His online blog is a treasure trove of tips, tricks, and tutorials that empower everyday individuals to take charge of their home’s plumbing health. Lee’s practical wisdom is not just about fixing leaks; it’s about imparting confidence and self-reliance. When he’s not writing or elbow-deep in a plumbing project, Lee is passionate about educating the next generation of DIYers, ensuring that practical skills are passed down and preserved.


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