A Guide To Smelly Hot Water

It can be quite alarming to turn on the hot water and get a nose-full of a foul odor. Often, the odor will be sulfur, which is a smell reminiscent of rotten eggs. Typically the odor isn't dangerous, but it will make the water unpleasant to use. The following guide can help you solve the problem. 

Common Causes

Most foul odors in the hot water supply are caused by the buildup of sulfate-causing bacteria in the tank, but in some cases, the cause may simply be mineral buildup from hard water. Bacteria problems are typically only in the hot water supply, and not the cold, because the warm tank temperature encourages their growth. Bacteria and mineral odor issues tend to be more common if you are on well water, but they can occur on municipal water, as well. If you have a gas hot water heater, there is a very slim chance that fuel is somehow leaking into the water and resulting in the odor. Your water heater repair technician can test your water to determine the specific cause of the odor.


You typically won't need to replace your tank for a foul odor. Your repair tech will flush out the water in the tank, first by draining the water already in the tank and then running fresh water through to remove any residue or sedimentation. The anode rods in the tank, which are designed to trap minerals so they don't accumulate in the water, may also need to be replaced. If the cause of the odor is due to bacteria, then the technician may also sterilize the inside of the tank to ensure all bacteria are destroyed in order to prevent regrowth. Gas lines will also be inspected to make sure there are no issues with the fuel system.


Prevention depends on the cause. If hard water mineralization is leading to bad odors, then your tech may install additional anode rods and recommend more frequent heater flushing. You can also install an inline or whole house water softener to remove the minerals before they make it into your water supply. When well water is to blame for bacteria growth, then you may need to begin chlorine treatments of your well to ensure the water is pure. A combination of frequent water testing and chlorine will typically eliminate all odor problems.

Contact a hot water heater repair service, such as ATWH, if you need help eradicating a bad odor from your heated water supply.