If you’ve ever turned on the hot water and caught a whiff of rotten eggs, your water heater might be the reason. There’s a small but important part inside your tank that often gets overlooked, and it plays a big role in both protecting your system and sometimes creating that odor. It’s called an anode rod, and understanding how it works can help you get rid of the smell and avoid future problems.
At A.J. LeBlanc Heating, we’ve helped many homeowners with this exact issue, and we’re here to explain what’s happening.
What Does an Anode Rod Do?
The anode rod is a metal rod located inside your tank-style water heater. Its main job is to attract corrosive elements in the water so the inside of your tank doesn’t rust. This process is known as "sacrificial protection" because the rod slowly corrodes over time instead of the tank. Without it, your water heater wouldn’t last nearly as long.
What Are Anode Rods Made Of?
There are three main materials used to make anode rods:
- Magnesium: Magnesium rods offer excellent corrosion protection but can sometimes cause odor issues, especially when paired with certain water conditions like well water or soft water.
- Aluminum or Aluminum-Zinc Alloy: These are better suited for hard water areas. They don’t wear down as quickly as magnesium and are less likely to react with bacteria in a way that produces bad smells.
- Zinc (typically part of an aluminum-zinc mix): Zinc helps control odor by neutralizing sulfur bacteria. Most zinc rods are actually aluminum rods with a small amount of zinc added.
Why a Brand-New Water Heater Might Smell
Many homeowners are surprised to learn that their old water heater never had any issues, but the brand-new one smells like sulfur. That’s often because manufacturers have started using magnesium rods more frequently in new water heaters. While magnesium does a great job preventing corrosion, it’s also more likely to react with sulfur in the water or bacteria that live in some well systems.
So even if your last heater didn’t cause a smell, the newer one might simply because of the material used in the new rod.
What Causes the Rotten Egg Smell?
The odor comes from hydrogen sulfide gas, which is produced when bacteria in the water interact with the magnesium rod. These bacteria feed on sulfur compounds, and when they break them down, the result is that familiar rotten egg smell. It usually shows up in the hot water because that’s where the chemical reaction is taking place inside the tank.
How to Get Rid of the Smell
If you’re dealing with smelly hot water, here are a few proven solutions:
- Switch to an aluminum-zinc rod: Simply replacing the magnesium rod with a different material can stop the reaction and eliminate the odor.
- Install a powered anode rod: These rods use a small electrical current instead of relying on corrosion. They protect your tank without encouraging odor-producing reactions.
- Flush and disinfect the tank: This can help reduce or eliminate the bacteria that are causing the smell.
- Use a water treatment system: If you’re on well water or have naturally high sulfur content, filtration or conditioning can make a big difference.
When Should You Replace the Anode Rod?
Most anode rods last about three to five years, depending on the quality of your water. If your water heater is more than a few years old and the rod has never been checked, it might be time to take a look. Replacing a worn or reactive rod is an easy and affordable way to extend the life of your water heater and improve water quality.
Call the Experts at A.J. LeBlanc Heating
Since 1928, A.J. LeBlanc Heating has helped New Hampshire homeowners stay comfortable with reliable plumbing, heating, and cooling services. Whether you need to fix smelly hot water, replace a failing rod, or upgrade to a new water heater, our licensed plumbers are here to help.
Give us a call today to schedule service or request a free estimate. We’re a family-owned business, and we treat your home like it’s our own.
