Rotten Egg Smell in Water Heaters
The most common cause of smelly water in a water heater is bacteria. The bacteria reacts with the anode rod in your water heater to produce the smell. Aluminum and magnesium anode rods are the types that bring the smell. Smelly water is most common in buildings connected to a well system. Water softeners can also increase the problem of smelly water significantly.
The Wrong Way
Some plumbers may recommend you remove your anode rod in your water heater. This will work, however it will void your water heater's warranty and it will also decrease its life dramatically. See our section on anode rods for more information. Another common misconception is to replace an aluminum anode rod with a magnesium anode rod. This solution is ineffective as they both react with the bacteria causing the smell.
To rid your water heater of the smelly rotten egg smell, the long term solution is changing out your aluminum or magnesium anode rod with a zinc-aluminum anode rod. A zinc-aluminum anode rod is made mostly of aluminum but has enough zinc to combat the rotten egg smell. Zinc-aluminum anode rods are relatively inexpensive and can be installed by most local plumbers. Removing a water heater anode rod is very difficult, since they are installed very tight inside the water heater tank. Usually a large socket with a cheater bar is required to removed these. They also make a special tool for removing these, this tool costs over $500.
Water softeners can contribute to a smelly water heater as well. A zinc-aluminum anode rod usually cannot fix the smell if you use a water softener. In most cases the problem can be fixed with a powered anode rod. The powered anode rod will not make your water heater smell because instead of having contact with the water, it releases a small electrical current through the water to do the job that other types of anode rods do. Powered anode rods are more expensive but if you cannot stand the rotten egg smell and you have a water softener this may be your only realistic choice.