Cause

• A hot water heater contains a magnesium rod. This rod can react with dissolved sodium in your water, resulting in the creation of hydrogen sulfide. Hydrogen sulfide is what gives your water a smell of sulfur or rotten eggs. Alternatively, sulfur-reducing bacteria may be present in the hot water heater, which produces hydrogen sulfur gas, according to the Nebraska Department of Health and Human Services.
  
  

Solution

• Eliminate the bacteria in a hot water heater by increasing the temperature of the hot water heater to above 140 degrees Fahrenheit. Maintain it there for eight hours. Drain the water from the tank. Another alternative is to replace the magnesium rod in the hot water heater with an aluminum one.
  
  

Considerations

• When turning up the temperature of the hot water heater, be sure to warn everyone in the house so they are not scalded by the abnormally hot water. Consult the hot water heater's warranty before making any adjustment to the magnesium rod because altering the appliance could void the warranty, according to Ohio State University.