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Why Does My Hot Water Smell Like Rotten Eggs?

Tired of a nasty rotten egg smell every time you turn on your hot water?

The reason you’re smelling this odor is because of a chemical compound called hydrogen sulfide. Outside of the unpleasant smell it creates, hydrogen sulfide can also harm your home’s pipes and cause discoloration in sinks and other plumbing fixtures.

Needless to say, you’ll want to rid your water heater of hydrogen sulfide ASAP.

In this blog, we’ll explain:

  • How hydrogen sulfide got into your water heater in the first place
  • How to get rid of the rotten egg smell
  • How to prevent hydrogen sulfide buildup in the future

Want a plumber to help you get rid of the bad smell? Our plumbers are standing by, ready to help!

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How hydrogen sulfide got into your water heater in the first place

Hydrogen sulfide could have formed inside your water heater if:

  1. Your water heater has a corroded anode rod
  2. Your water supply has a high count of sulfur-reducing bacteria (SRB)

Let’s look at both of these problems in more detail.

Problem #1: Corroded anode rod

Tank water heaters have a component called an anode rod. An anode rod protects the inner lining of the tank by drawing corrosive minerals to it. This way, the rod will corrode instead of the tank itself.

An anode rod in a gas water heater

The majority of anode rods are made of magnesium or aluminum. Once an anode rode has become corroded, naturally-occurring sulfates in the water can react with the magnesium or aluminum and create hydrogen sulfide—hence the nasty odor.

Problem #2: High count of SRB in water supply

Sulfur-reducing bacteria love dark, oxygen-free places like your water heater. When SRB feeds off of sulfates in the water, they chemically alter sulfates in your water and turn them into hydrogen sulfide. If your water heater has a high count of SRB, that could explain the rotten egg smell.

However, this problem isn’t very common unless you get your water supply from a private source like a well. Most of us get our water from a public water supply which is cleaned by a water treatment facility, so the SRB count in our water is not usually very high. That said, if you get your water from a private source, this could be the problem.

Now that you know what causes the stinky hydrogen sulfide compound, let’s look at how you can get rid of it.

How to get rid of the rotten egg smell

Depending on which problem you have, a plumber will need to do one of two things:

  1. Replace the corroded anode rod and disinfect the tank
  2. Perform a shock chlorination treatment in your well

Solution #1: Replace the corroded anode rod and disinfect the tank

First, a plumber will remove the corroded anode rod out of your tank, careful not to break the corroded rod as it’s removed.

Once the anode rod is replaced, a plumber will need to flush your tank to get rid of the existing hydrogen sulfide. A plumber may also need to use a disinfectant inside the tank depending on how bad the smell is.

Solution #2: Perform a shock chlorination treatment in your well

After a plumber flushes your water heater, if you still get the same rotten egg smell, it may mean you have a high count of SRB in your water supply. If that’s the case, a plumber will need to perform a shock chlorination treatment. The high concentration of chlorine will kill any remaining SRB and help to reduce the odor in your water heater.

How to prevent hydrogen sulfide buildup in the future

After a plumber helps you kill off the hydrogen sulfide, you’ll want to have them take steps to prevent the bad smell from coming back. Below are two ways to prevent hydrogen sulfide from forming in your tank again.

Preventative method #1: Have a plumber use a high-quality zinc replacement rod

When your plumber removes your anode rod in the first place, ask them to replace it with a high-quality zinc anode rod. Zinc doesn’t negatively react to sulfates the same way as magnesium and aluminum do, so you likely won’t get the rotten egg smell if you use one.

Preventative method #2: Have a plumber install a water purification system

The first step will be to have a plumber perform a water quality test. The purpose of this test is to determine what contaminants are in your water, and in what concentrations. After the test, the plumber can recommend a water purifier such as a carbon filter, hydrogen peroxide chemical feed or another solution that can kill hydrogen sulfide.

Want a Minneapolis-St. Paul plumber to help you eliminate the rotten egg smell?

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