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Conquering Rotten Egg Odor: The Power of the Right Anode Rod

Hot water that smells like rotten eggs. If you’ve ever dealt with this odorous issue, you understand how unpleasant it is. You go to take a calming bath, but the odor prevents you from de-stressing. You run water to make tea, and it smells like sulfur. Luckily, this problem is more common and fixable than you may think. 

One possibility for the smell is the anode rod in your water heater, which may be reacting with bacteria from inside your well water. The bacteria is not dangerous, and neither is the smelly water, and luckily, fixing this issue is simple. You will simply need to replace your anode rod with one of an approved material.

Use a zinc alloy anode rod to eliminate smelly hot water. With aluminum and magnesium rods, corrosion releases free electrons that are used by sulfate-reducing bacteria in the presence of water to form hydrogen sulfide gas. Do not remove the anode rod completely, as the water heater’s life will be shortened.

How to Tell if Anode Rod Is Making Water Smell

If it is a rotten egg or sulfur smell coming from your water, it is a likely bet that either your well water or your anode rod is the culprit.

You can determine whether it is a sulfur bacteria present in the water itself producing the smell by checking if your cold water smells or if it is just the hot water. If it is just your hot water, your water heater is likely the source, rather than the well itself.

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Only certain types of anode rods result in smelly water. Determine if your anode rod is made of magnesium or aluminum. These two minerals are most likely to produce the smelly odor.

The chemical reaction that creates smelly water is made worse by softened water. If the smell is most common with hot water, if you have a magnesium or aluminum anode rod, and especially if you have softened water, it is a safe bet to guess where the smell is coming from.

Why Does Anode Rod Make Well Water Smell?

Anode rods are inserted into water heaters to corrode instead of the water heater tank. The highly reactive material of the rod breaks down, sparing the tank.

A certain type of anaerobic, sulfate-reducing bacteria is present in the deep environment of wells. This bacteria comes up from the well into the water heater.

Anode rods are made of metals like magnesium, aluminum, or zinc. When the anode rod corrodes as it is meant to, these metals are ionized, and free electrons are left floating in the water. These free electrons can be used by the sulfate-reducing bacteria to create hydrogen sulfide gas, which smells like rotten eggs.

With aluminum and magnesium rods, the bacteria freely reduce the sulfate and produce hydrogen sulfide, but zinc anode rods tend not to cause your water to smell. Why?

Well, it comes down to the toxicity of zinc to bacteria. Zinc oxide can permeate the lipid cell membranes of the sulfate-reducing bacteria, accumulating inside the cell, damaging it, and eventually killing it. This is a slower reaction, but there is an alternative and much more rapid toxicity route.

Zinc ions, which are produced through corrosion, are considered to be extremely toxic to bacteria. The mechanism of this is not quite certain, however. This is a fast process, killing bacteria outright.

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Thus, zinc or zinc alloy anode rods still produce electrons that can be used by bacteria, but the zinc kills the bacteria, which means hydrogen sulfide gas cannot be produced.

Heat speeds up chemical reactions, so the hotter you keep your water heater, the faster the smell will be produced. Turning down your heater to the recommended 120 °F may help combat the smell to a limited degree.

Can I Remove the Anode Rod?

You can remove the anode rod, and, in fact, you should, after 3-5 years, but it should always be replaced with a new one. When dealing with smelly well water, many people just remove the rod altogether, whether of their own volition or at the advice of “the internet”. So, what happens when you take the anode rod out and don’t replace it?

Removing Rod Will Likely Eliminate Smell

If you remove the water heater’s anode rod and do not replace it, the smell will likely go away because there are no longer free electrons available for use by the bacteria. Removing the rod involves first of all, turning off the power and water connected to your water heater.

There should be instructions in your water heater’s user manual as to where to find the anode rod. You’ll need to locate the rod, which will be on top of the water heater unit. You will then want to drain some of the water from your tank using a garden hose. This water will be hot, so watch out!

Keeping some water in your tank while removing the rod is a good idea to weigh down the tank for leverage. You will need a wrench to loosen and remove the anode rod and it may be helpful to have a helper for removing the rod.

Negative Consequences of Removing Anode Rod

Anode rods are not imperative to the functioning of a water heater, but they are crucial to the heater’s lifespan.

They prevent corrosion of the tank diverting corrosive elements from to the rod itself. Since the rod contains metals that are more reactive than the tank’s walls, they corrode instead of the tank. Without the anode present, the tank will be vulnerable to fast corrosion from the hot water.

Broken water heater with heating elements, on wooden background

Corrosion in a water heater is no small matter. If corrosion of the tank occurs, the system will become leaky and need to be replaced. It may even burst. The sacrificial anode rod is an important preventative measure. You don’t want to wait until your tank is corroded and leaking to do something. By that time, you’ll need to replace it.

Without an anode rod, your water heater will likely lose half of its lifespan. Most water heaters have a glass-lined steel tank and last for 8-15 years. While most water heaters come with a sacrificial anode rod, if this is removed, the heater will last closer to 5 years or even less.

With replacement of the anode rod every three years, a water heater should last closer to 15 and can even last up to 20 years.

Fixing Smelly Well Water Without Removing Anode Rod

The existing rod should be removed and then replaced with one made of the correct material.

Anode rods made of magnesium or aluminum should be replaced with one made of zinc or a aluminum/zinc alloy. This alloy eliminates the smell since zinc is the primary material. These are the cheapest alternative to magnesium and aluminum anodes you will find.

Then, if the smell suddenly returns, this can be a good indication that the anode rod has been depleted and needs to be replaced.

However, with softened water, replacing the anode with a zinc alternative will likely not be enough to fix the problem. This is because softened water speeds up the reaction that creates hydrogen sulfide gas.

For softened water, the anode rod should be replaced with a powered anode rod. This is the most expensive type of anode rod, spanning from about $100-$200 but it is also permanent, and it does not risk producing the smelly odor because it does not contain magnesium or aluminum.

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Powered anode rods (amazon link) work by using electrical pulses to prevent corrosion. They are made of a highly durable internal metal such as titanium, and they are plugged into the wall to provide their power. Powered anode rods are the best option to deal with smelly water and corrosion since they are long lasting and don’t require regular maintenance.


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