Why Does My Plumbing Smell Like Rotten Eggs?

Guest Post Edited & Posted By Mona of Ace Cleaning

Much of the plumbing in our homes is reasonably complicated. There are a lot of elements involved, and if one of these elements begins to fail, this can often lead to tons of issues within the home, be it faulty plumbing systems or foul smells. One of the most common plumbing issues is that it smells like rotten eggs.

What causes plumbing to smell like rotten eggs?

The most common source of sewer odor is a natural gas called hydrogen sulphide gas. It is commonly known as sewer gas, and the sulphur in the gas creates the rotten egg smell that causes many people to suffer within their homes. The sulphur smell is often the first sign of an issue within the plumbing system.

Information taken from Rider Drains Cleaning & Repairs indicates that hydrogen sulphide gas is not inherently harmful. However, it can cause dizziness, nausea, and even skin and eye irritation if left alone too long. The smell usually occurs in bathroom sinks and bathroom toilets, but occasionally may appear in the kitchen sink. The most common cause of a smelly kitchen sink tends to be a blocked drain, not hydrogen sulphide gas. If your kitchen sink smells, check the garbage disposal and try to unblock it and clean it. It is usually possible to do this by pouring a bit of baking soda and white vinegar down the sink drain.

There is a list of things that might cause a plumbing system to smell of rotten eggs, and they are:

1. Contaminated water

Often, the hydrogen sulphide rotten egg smell comes from the water itself. Water can be easily contaminated, especially if it is stored in a hot water tank. Contaminated water can be caused by a corroded magnesium anode rod within the hot water tank or water heater. The corrosion is caused by the anode rod reacting with the water around it. Alternatively, contaminated water might be caused by sulphur bacterial growth. Luckily, the contaminated water is not harmful.

1. Contaminated sink drain

The overflow drain on a sink is the small hole on the back of the sink bowl. It works as a secondary sink drain to prevent the sink from ever overflowing. However, it can get contaminated by an accumulation of bacteria at the end of the overflow drain, which can then release hydrogen sulphide gas, leading to a sulphur smell within your home.

1. Outgassing

Outgassing is used to describe the release of unpleasant gases from plastic over time. This can include a range of gases, including sewer gas. It occurs when the sink is made from a plastic material, or if you have old drywall nearby.

1. Dry P Trap

All of the items in your home that use plumbing systems will have a P trap. This is a U-shaped bend of pipe that is usually full of water to trap the sewer gas and prevent your home from smelling like rotten eggs. However, sometimes the p trap dries out due to evaporation or a small leak, and that leaves the P trap dry and empty, allowing the foul smell to escape up from the sewer lines, making your sink smell.

1. Blocked vents

Most plumbing in your home will be connected to a series of vents that allow fresh air in and foul smells to escape. Sometimes, these vents get clogged or blocked. Blocked vents can cause a few issues when it comes to the house’s plumbing. For one, they can cause the toilets and sinks to drain slowly, even when chemical cleaner and boiling water or baking soda are used to clear the pipes. They can also redirect the foul sulphur smell towards the home, meaning that the hydrogen sulphide fills your kitchen or bathroom instead of being ushered away.

How to get rid of the rotten egg smell in your home

The first step in getting rid of the rotten egg smell is to identify where the smell is coming from. Is it coming from your kitchen sink? Your sink drain? Does it only appear when the hot tap is on? These are all important things to ask yourself. Often, the sulphur smell will only be coming from one sink. To identify where the odor is coming from, you can try filling a cup with water and taking it outside and smelling it, or you can determine where the smell is coming from by sniffing around the smelly room.

Once you have determined the source of the problem, there are a few things that you can do. It simply depends on what you’ve identified as the issue.

For contaminated water heaters or water tanks:

The best way to remove the smell of contaminated water is to decontaminate the water. To do so, you will need to hire a plumber to come and remove the corroded anode and replace one that has yet to undergo a corrosive chemical reaction. If you think your water has been contaminated by bacteria instead, chlorinating the water will help to reduce the smell and tackle the bacteria.

For contaminated overflows:

There are three ways to fix a contaminated overflow. You can:

1. Fill the sink with hot water and bleach and let the water soak into the overflow until the sink is half empty. Then drain with boiling water.
2. Pour a bleach containing hydrochloric acid straight down the overflow. 
3. Pouring baking soda and vinegar down the overflow is a gentler option.

The first and second methods are stronger and more likely to kill bacteria, but third method is great if you want to avoid harsh chemicals.

For outgassing sinks or drywall:

Simply replace your sink or drywall to remove the rotten egg smell if you think it is being caused by outgassing.

For dry P traps:

The best way to clean a dry p trap is to take it apart, clean it with baking soda and vinegar, and then replace it and flush it with water. Fill the trap once again by running your bath or shower, sink, and unused toilet all at the same time.

For blocked vents:

It is as simple as locating and unblocking the blocked vents to eliminate foul odors. You should notice that the smell dissipates after you clean and replace them.