If you’re asking, “Why does my water smell like rotten eggs?” the answer usually involves your water chemistry and plumbing conditions. The smell is unpleasant and can indicate underlying problems in your water system that need attention.
The odor most often smells like rotten eggs, signaling the presence of hydrogen sulfide gas or bacteria. While not always a danger, this situation should never be ignored.
What Causes Water to Smell Like Rotten Eggs?
The most common cause of water smelling like rotten eggs is hydrogen sulfide, a gas that forms when organic matter decays in oxygen-deprived environments. It is especially present in well water and older plumbing systems.
Another frequent source is sulfur bacteria, which thrive in areas like your water heater, pipes, or private wells. These bacteria create hydrogen sulfide gas as a byproduct when consuming sulfates in water.
The rotten egg odor may also result from chemical reactions inside the water heater tank. These reactions often involve a metal rod called a magnesium anode, which reacts with bacteria and sulfates.
In some cases, the odor is intensified by water stagnation. When water sits still in pipes or fixtures for too long, bacteria multiply rapidly, increasing the production of hydrogen sulfide gas.
This can occur overnight or during long periods of disuse, such as vacations. The construction of your plumbing can also influence the smell. Older homes or buildings with iron or galvanized steel piping are more prone to hosting iron bacteria, which thrive in similar conditions to sulfur bacteria.
If your home draws from city water, it’s still possible to encounter this problem. Although city water is treated before reaching your home, aging infrastructure or dead-end water mains may still allow bacteria and gas to accumulate.
Is Hydrogen Sulfide the Main Culprit?
Yes, hydrogen sulfide is the leading cause of the rotten egg smell in water. It’s a naturally occurring gas that carries the signature scent often noticed when water smells like rotten eggs.
This gas is most noticeable in hot water because heat accelerates the release of hydrogen sulfide gas into the air. This explains why hot water smells stronger than cold water in many homes.
When this gas is present, it can lead to rust stains, corrode pipes, and degrade water quality. The longer it stays in your plumbing system, the worse the damage can become. The process by which hydrogen sulfide forms is not always visible, making it more frustrating for homeowners.
It occurs naturally as a result of decaying vegetation underground or chemical interactions between minerals in the soil and water. When hydrogen sulfide gas accumulates in your plumbing, it doesn’t just impact smell. It also causes damage to the internal components of your appliances.
Even if the smell is relatively new, it may indicate the long-term presence of bacteria or an aging anode rod. In either case, proactive investigation and treatment are the most effective ways to preserve your plumbing and protect your investment.
Could Your Water Heater Be Causing the Rotten Egg Smell?
One of the most overlooked contributors to water that smells like rotten eggs is the water heater itself. When the odor only appears with hot water, this is the most likely culprit. Inside most water heaters, a magnesium anode is installed to protect the tank through a process called corrosion protection.
While effective in preventing rust, this metal rod can react with sulfate and bacteria to produce hydrogen sulfide gas, which smells like rotten eggs. In some cases, switching to a powered anode or replacing it with an aluminum/zinc alloy rod can significantly reduce or eliminate the rotten eggs odor.
If your hot water heater hasn’t been serviced in a while, buildup and sediment at the bottom of the tank may also harbor sulfur bacteria, worsening the situation. Routine maintenance of your water heaters is key.
Flushing the tank, checking for sediment, and ensuring proper function of the anode all contribute to consistent water quality and fewer issues with odor.
Can Bacteria in the Plumbing Cause the Smell?
Yes, sulfur bacteria and sulfate-reducing bacteria are often the reason why your tap water might smell like rotten eggs. These bacteria thrive in stagnant water inside plumbing or water heaters.
They multiply rapidly in a warm environment, particularly in hot water heaters that aren’t flushed regularly. As bacteria grow, they produce hydrogen sulfide, resulting in a foul sulfur smell.
This kind of contamination often leads to clogged pipes, odor buildup, and recurring odor problems unless treated properly. If left untreated, other bacteria may also flourish in your pipes.
Some homes may experience multiple strains of bacteria coexisting in the system. In addition to sulfur bacteria, iron bacteria, and other bacteria can flourish in neglected systems, compounding the problem.
The combination of heat, minerals, and stagnant water creates ideal conditions for colonization. The longer bacteria are left to grow, the harder they become to eliminate.
What Role Does Cold Water Play in Rotten Egg Odors?
Although hot water is more often the source, cold water can also smell like rotten eggs under certain conditions. When cold water smells, it may indicate contamination at the source or insufficient flow in the lines.
Low flow in cold water faucets, especially those seldom used, allows bacteria to flourish. The cold water in these pipes can build up odor-causing gas and bacteria over time. Cold-side contamination may also occur in areas with high levels of sulfur or sulfate in the groundwater.
In such cases, installing a whole-home water filtration system may be necessary.
How Can You Identify the Source of the Smell?
To locate the source, first test whether the cold water or hot water is affected. If only the hot water produces the odor, the issue likely lies in your water heater. When both cold water and hot water are affected, the problem likely originates from the water supply or well casing.
Isolated smells at specific cold water faucets may point to contamination in plumbing fixtures. If the smell fades after running the water for a few hours, the source might be a temporary bacterial bloom. However, if it lingers after several hours, a deeper problem is likely present.
What Are the Health Implications of Sulfur Smell in Water?
Although hydrogen sulfide at low levels isn’t toxic, the unpleasant smell can lead to headaches, nausea, and irritation. In small bathrooms with poor ventilation, inhaling this gas can cause discomfort.
More importantly, the odor may be a warning sign of other contaminants or other bacteria in your drinking water. Testing becomes vital when using well water or older infrastructure. The presence of coliform bacteria in conjunction with hydrogen sulfide could indicate a potential health risk.
If you’re unsure, avoid the urge to drink water with any unusual odor until a water test confirms its safety.
How Can You Get Rid of the Rotten Egg Smell in Your Water?
For issues inside your water heater, replacing the anode rod can stop chemical reactions that produce hydrogen sulfide gas. Swapping the rod for an aluminum-zinc alloy can drastically reduce odor.
Increasing the water heater temperature briefly may eliminate bacteria, but always follow proper safety precautions. Flushing your heater helps remove sediment and stop bacterial growth.
To treat the whole system, disinfecting with a chlorine bleach solution can kill sulfur bacteria in the plumbing. Installing a carbon filter or a water softener may help remove hydrogen sulfide gas from both hot and cold water.
A continuous chlorination system may be recommended for private wells with persistent bacterial problems. This maintains the microbial population under control and prevents the return of sulfur smell.
If the smell reappears despite treatment, further testing may be needed to detect hidden factors like well casing damage. Regular inspections and testing are key to success.
Should You Consider Installing a Shower Filter to Reduce the Smell?
Absolutely—if your hot water smells, it means your showers are affected by hydrogen sulfide gas. The smell intensifies with heat, and exposure may lead to eye or skin irritation.
A quality shower filter removes sulfur smell, bacteria, and excess gas directly from the water before it reaches your body. This results in better water quality and a more pleasant showering experience.
AquaBliss offers high-performance shower filters that target hydrogen sulfide, chlorine, and sediment. These filters restore comfort, protect your health, and are easy to install.
When Should You Call a Water Expert?
If the rotten egg smell returns quickly after DIY treatment, or if you’re unsure whether you’re dealing with hydrogen sulfide, sulfur bacteria, or another problem, professional help is crucial.
A certified water expert can perform lab-grade testing and recommend targeted solutions. Homes using well water are more likely to face this issue repeatedly. Private wells are especially vulnerable to bacteria and gas buildup and often lack municipal oversight.
In such cases, speaking with your local water expert or AquaBliss consultant can provide clarity. They may suggest in-depth inspections, advanced water filtration, or replacement of contaminated components.
Ready to Eliminate That Rotten Egg Smell?
So, why does water smell like rotten eggs? The answer is a combination of hydrogen sulfide, sulfur bacteria, plumbing system interactions, or neglected water heaters. If your water smells like rotten eggs, it’s often due to gas buildup in your heater or contaminated well water.
If your cold water smells, the issue could lie deeper in your water supply. Whether your water smells due to hot water heater problems, bacteria, or pipe corrosion, AquaBliss has solutions that restore fresh water and peace of mind. Visit AquaBliss.com today to explore our range of filters and maintenance tools.
You can also contact us to speak with a water care expert who can help eliminate the smell of rotten eggs once and for all.
