Why Does Your Water Heater Smell Like Rotten Eggs?

The odor comes from hydrogen sulfide gas. This gas can build up inside the tank under certain conditions, creating an odor that’s hard to miss once it reaches your hot water supply. 

Sulfur Bacteria in Your Tank

Sulfur bacteria thrive in warm, low-oxygen environments, making your water heater tank an ideal home. As the bacteria break down naturally occurring sulfates, they produce hydrogen sulfide gas. This process often happens quietly for months before you notice a smell.

The Anode Rod Connection

Your anode rod protects the tank from rust by corroding in its place. Magnesium rods, in particular, can react with sulfates and speed up hydrogen sulfide production. Swapping a corroded magnesium rod for an aluminum or zinc option can reduce this reaction.

How To Get Rid of the Smell

Knowing why a water heater smells like rotten eggs is only half the equation. The next step is addressing the bacteria and buildup causing it. A few approaches tend to work well together:

• Flush the tank: Water heater flushing removes sediment and stale water where bacteria collect.
• Raise the temperature: Heating water to 140 degrees may kill sulfur bacteria.
• Disinfect the system: Shock chlorination treatments target bacteria directly inside the tank.

Regular upkeep also helps prevent future buildup. Following basic water heater maintenance tips can keep sediment and bacteria from building up in the first place.

When To Call a Professional

Some smells clear up with a simple flush, while others stick around. If the odor returns quickly, it’s a sign of a deeper issue. A professional plumber can test your water and pinpoint the cause.