Hot Water Smelling Like Rotten Eggs? How to Fix It?

Let me ask you this: “Is the hot water which reaches your home likely to smell like rotten eggs? Well, the truth is that you are not alone. In fact, this problem is quite common and a lot of homes experience this. Before you get all kinds of crazy ideas why this can be the case, there is a logical explanation. Soil and rock formations in groundwater contain minerals including sulfur that combines with oxygen to form sulfates. In details, these sulfates will dissolve and are released into the groundwater.


Overall, water heaters are the main cause of the conversion of sulfates to hydrogen sulfate gas. Specifically, they have a warm environment where bacteria live. Anodes rods which are made of aluminum or magnesium meant to reduce corrosion within the water heater tank. In fact, these anodes rods have electrons which can help change sulfates to hydrogen sulfides. Usually, the anodes 30 to 40 inches long and 1/2 to 3/4 inches in diameter within the heater tank.

In addition, the smell of hydrogen sulfide gas in water is present at low temperatures. Actually, you can easily find out the cause simply by smelling the water coming from both cold and hot water taps. You can completely identify the factors which may contribute to the smell of hydrogen sulfide gas in hot water with one of the following methods:

Sulfur bacteria in the water softener

Image source: H2O Care

  • If the smell is from water treated with the water softener, from both the hot and cold water taps and not from untreated water, then the problem may be caused by the sulfur bacteria in the water softener.
  • In case the smell is from the hot water tap, then the problem is most likely to be from the water heater.
  • If the smell is strong in both cold and hot taps and it is also constant throughout, then the problem most likely results from hydrogen sulfide in the groundwater.
  • But, if the smell is strong in both taps once you open them then goes away or decreases while the water runs, or if the smell varies from time to time, then this can be because of the sulfur bacteria in the water distribution or well system.

What Should You Do?

Actually, there are several things you can do in order to stop the production of hydrogen sulfide gas in the water heater. In case you are not familiar with the workings as well as maintenance of the water heater, then just contact a professional to do the following things:

Replace the Magnesium Anode with Zinc/Aluminum Anode

In general, almost every water heater has an aluminum or magnesium anode attached to a plug on top of the heater. You can totally remove it just by turning off the water to release the pressure in the water heater and unscrew the plug.

Next, replace the aluminum or magnesium anode with an anode made of zinc alloy/aluminum and reattach the plug.

Additionally, removing the anode can help reduce the life of your water heater. You should consult a water heater dealer. Therefore, you can find out if a replacement anode made of zinc/ aluminum can be installed in your heater or not. Remember that a replacement zinc/ aluminum can help you protect the heater from corrosion without producing hydrogen sulfide gas.

Replace the Magnesium Anode with Zinc Aluminum Anode

Image source: YouTube

Disinfect and Flash Water Heater with Hydrogen Peroxide or Chlorine Bleach Solution

Flashing the water heater with chlorine or hydrogen peroxide can help kill the sulfur bacteria. However, in case some sulfur bacteria survive after flashing, the problem will return in a short amount of time. This can also happen allow the water heater to stay a long time without being used. Besides, hydrogen peroxide is safer to use when compared to chlorine bleach solution.

Increase the Water Heater Temperature

Keep in mind that increasing the temperature of the water heater to about 160 degrees Fahrenheit will  kill the sulfur bacteria. After that, flashing the water heater will help remove the dead bacteria as well as smell.


However, increasing the temperature of the water heater might be extremely dangerous. Therefore, you need to consult the dealer or manufacturer on whether the relief valve is functioning and any other recommendations which you should enforce.

I recommend you to lower the thermostat settings in order to make sure the water temperature is slow down following the procedure. That way, you can avoid scalding from hot water as well as high energy costs.

Install a Powered Anode Rod

In case installing a zinc/aluminum anode can’t solve your problem, then you need to install a powered anode rod. This is because these rods don’t have aluminum or magnesium for bacteria to react with. Therefore, they do not need any replacement and there will definitely no smell.

Nonetheless, powered anode rods are commonly much more expensive than the other standard rods. Just make sure that you consult a professional so that they can install the right anode head for your water heater. Keep in mind that installing the wrong head can’t help solve the problem and this can even result in a short circuit.

What Not to Do

Replacing aluminum or magnesium anode with a zinc/aluminum anode is the cheapest way to fix the hydrogen sulfide gas problem in your water heater. In fact, zinc is the key ingredient as aluminum alone cannot eliminate the problem. Moreover, you should never try to do the following:

– Do not soften the water in the tank since softening may increase water conductivity. Furthermore, this can also speed up bacteria anode reaction as well as increase the hydrogen sulfide gas produced.

– You should never put 2 anodes in your tank because even 2 zinc/aluminum anodes can completely make the smell worse.

– Refrain from installing any parts or doing any repairs and maintenance in case you are not familiar with the workings of the water heater. Instead, just seek help from a professional so as to avoid damaging the water heating system unintentionally.

The above tips should be enough to help you get rid of the smell of rotten eggs in your water. Consult an expert in water heaters and water distribution systems if you’re still unable to solve the problem.

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