A foul odor from water is fairly common. If you notice a rotten egg smell every time you open a faucet, and are asking what causes it, the answer isn’t too complicated. We’re going to be discussing how water gets to smell like rotten eggs and what you should do to eliminate the problem.
The bad smell in water, that is often compared to rotting eggs, isn’t a serious health hazard and is actually quite common. While you need not be too concerned about the safety of your family, the odor is certainly unpleasant. It can be downright embarrassing when you have guests. Unlike similar embarrassing smells, you can’t blame the dog for this one!
What causes the rotten egg smell in water? How do you fix it?
Let’s find the answers.
The Cause of Rotten Egg Smell in water
Well water in particular is susceptible to an odor that is best described as bad eggs. Hot water heaters, especially if they haven’t been used for long time, will also develop the same nasty smell. The odor can also originate in basements and drains.
The smell is caused by hydrogen sulfide gas in the water. Generally, this is caused by sulfur reducing bacteria. The bacteria feed on sulfur and release the gas into natural water supplies.
Sulfur can also accumulate in water heaters that use a magnesium rod to reduce corrosion. Chemical reactions with magnesium can reduce sulfates, forming hydrogen sulfide. Occasionally, chemical reactions within water softeners can also cause hydrogen sulfide.
Is Hydrogen Sulfide Dangerous?
Although poisonous and flammable, the distinct odor of hydrogen sulfide, usually described as being similar to rotten eggs, makes it easily detectable. Even a small amount of the gas in water produces a pungent odor that is immediately recognizable. You should not drink water if it has a rotten egg smell.
Hydrogen sulfide gas in tap water is reasonably safe and does not present a fire risk. However, if you notice a rotten egg smell from areas where ground water may accumulate, you should be aware of the possible risk that it could cause an explosion.
Because sulfur hydroxide is corrosive, it can cause damage to your pipes, water heaters, and appliances that use water, like washing machines.
How to Get Rid of the Rotten Egg Smell in Your Water
The first step to eliminate your hydrogen sulfide problem is to identify the cause. This requires a simple three-step test.
Fortunately, it is usually easy to get rid of sulfur hydroxide in water. Having identified the cause, you can follow the appropriate remedies as listed below.
Sulfur Hydroxide in Water Heaters
If you only notice an unpleasant odor when using hot water, the cause is sulfur hydroxide accumulating in your water heater. Generally, this happens if you haven’t used hot water for a while.
By opening a hot water faucet and allowing the water to run until the contaminated water is flushed from the water heater, you should get rid of all the sulfur hydroxide in your water heater. This means allowing the water to run until the smell is no longer detectable.
While flushing your water heater usually resolves the problem, it can sometimes be more complicated. If you’re unable to get rid of the odor by running a hot water faucet, you should contact a qualified hot water technician who will inspect the system to determine the cause.
Sulfur Hydroxide in Cold Water
There can be three reasons why cold water has a rotten egg smell. It is possible that bacteria in your water pipes is causing a buildup of the gas. Similar to gas accumulating in your water heater, this can be resolved by flushing the pipes. Simply allow the water to run out of a faucet until the smell goes away.
If flushing the pipes doesn’t do the trick, you need to consider the possibility that your water supply is contaminated. This is fairly common with well water. The solution would be to install a whole house water filtration system that is capable of removing sulfur hydroxide from the water.
A less common cause for the rotten egg smell in your water could be contamination in your water softener. If you have a water softener, clean it thoroughly, including the brine tank. Manufacturers of water softening systems usually recommend cleaning the water softener at least once a year. This is not only to prevent bad odors but also bacteria that could cause more serious harm.
Sulfur Hydroxide in Stagnant Water
Sulfur reducing bacteria exist naturally in many ground water supplies. This water can easily seep into your basement and cause a persistent rotten egg smell in the home. Because the gas is constantly being released into the confined space of a basement, it can be a serious fire risk as the gas is highly flammable.
If you have a sulfur hydroxide problem in your basement, you should install a sump pump to remove to the water that collects there. You should also install a vent pipe which will allow the gas to escape.
Another area where stagnant water can cause bad odors is your drains. You can flush drains by allowing water to run through them until the smell disappears. Adding a little chlorine bleach to your drains will kill bacteria which can cause many different types of odors, including sulfur reducing bacteria.
Water Filters that Remove Sulfur Hydroxide
If you regularly smell rotten eggs when you use water in your home, you probably need to filter the water to remove the sulfur hydroxide that is causing the smell. The best way to achieve the desired result is to install a whole house reverse osmosis filtration system.
A reverse osmosis (RO) membrane is highly effective at removing the bacteria that causes the bad smell, as well as other contaminants in water. An RO membrane is capable of removing over 90% of all known toxins and contaminants in water.
As wonderful as an RO filter is, it probably won’t entirely eliminate sulfur hydroxide and some other contaminants, especially chemical odors that are small enough to pass through the membrane. For this reason, whole house RO filters use several stages of filtration.
A basic 3-stage RO system will include a sediment filter as the first stage of filtration. The purpose of this stage is to remove debris, sediment, and rust that could block the more effective filters and reduce their lifespan.
The second stage utilizes an RO membrane that removes dissolved salts and particles to around 1-micron in size. The contaminants that are removed from the water are flushed down the drain, ensuring that the filter remains clean and efficient.
Once the water has passed through the RO filter, a third stage of filtration removes chemicals and other contaminants that could cause odors and affect the taste or appearance of the water. This stage utilizes activated carbon. If the water has a high concentration of contaminants, an additional activated carbon filter can be added as a fourth stage.
The filtered water is stored in a tank to ensure that you always have clean, pure water on tap as you need it. Because it’s possible that small amounts of contaminants may accumulate in the tank, a 4th stage of filtration can be added to filter the water leaving the tank. This would be a post activated carbon filter that removes any residual contaminants that could affect the taste, smell, or color of the water.
In addition the stages of filtration already mentioned, there are other filters that can be used to improve the quality of your water. A water softener will remove hard minerals, like calcium and magnesium from the water.
If you use well water, you may want to protect your family from infections caused by bacteria, viruses, and parasites (pathogens). A UV or silver filter can be installed as a final stage of post filtration to ensure that no pathogens have contaminated the water that you drink.
While a rotten egg smell in your water is unpleasant, it is not a great health risk and can be dealt with effectively once you’ve identified the cause of the problem. First, you need to determine whether sulfur hydroxide is accumulating in your pipes, water heater, drains, or basement.
Once you know the cause, it is pretty easy to find a remedy. You should start by flushing your pipes and/or water heater. Clean your drains and use a disinfectant to kill any bacteria that could be causing odors in your drains.
The final and most effective way to keep your water free from all odors (and other contaminants) is to install a whole house water filter. Although these systems can be quite costly, they last for a very long time and have numerous benefits.