Hot Water Heater Anode Smell

Water heaters are an integral part of our homes, and you should rectify any problems that arise. However, one of the most reported problems is a foul smell coming from the heater. The smell is close to that of rotten eggs, and it can be very uncomfortable. The predicament that needs resolving or you can diagnose it yourself. In this guide, we explore the options you can use to diagnose and troubleshoot a water heater with a foul smell coming from the anode.

Troubleshooting the Odor

Many of the water heaters in circulation today comprise of a steel tank, and a glass lining. They also have an anode rod in the reservoir that prevents the tank from corroding. Instead, the rod corrodes making the tank safe for use for a long time. Some places will have smelly water especially if your supply of from the municipal water department. Due to a high level of sulfur in the water, hot and cold water will have a pungent smell, and it gets worse with time. You will only notice the smell in hot water and not in the cold water.

The anode protects the steel from corrosion, but it increases the generation of hydrogen from the steel tank. The hydrogen fuses with the sulfur in the water to form the smelly hydrogen sulfide gas in the water reservoir. The standard procedure is to replace the standard manufacturer’s aluminum or magnesium anode with an aluminum/zinc anode given that the water has not been with a softener. This type of anode reduces the amount of H2S. However, aluminum is a health hazard so refrain from using the hot water for cooking or drinking.

How to Make It Worse

Softening the water.
If you have hard water, the use of water softeners increases the water’s conductivity in the water heater and enhances the rate of corrosion on the installed anode. Water softeners will lead to you having smelly water.

Lack of use of the water heater.
Water heaters that are hardly used create a conducive environment for the buildup of the hydrogen sulfide gas in the water tank. When you use the water for the first time, your water will smell like rotten eggs. Here are ways you can use to get rid of the smell from your water heater.

Change your Anode

As stated above, replacing the anode with an aluminum/zinc anode will reduce the generation of hydrogen gas in the water heater tank. However, for a more lasting solution, use a powered anode and statistics show that it has a 99.75% success rate. A certified professional plumber best handles this work.

Use Hydrogen Peroxide (H2O2)

Hydrogen peroxide is a sure way to combat the hydrogen sulfide gas. The regular 3% hydrogen peroxide is available from any drug store for less than a $1. Use one cup to every ten gallons of water to combat the gas. Here is the procedure of sanitizing your water heater.

• Turn off the manual switch on the electric water heater or if you have a gas heater, turn down the control on the Pilot but do not turn it off completely, then close the cold-water inlet valve.
• Open one hot water tap and the temperature and pressure valve to relieve the pressure from the tank.
• Drain enough water to accommodate the hydrogen peroxide and remove the T&P valve, water heater outlet, and the anode. Add enough hydrogen peroxide equivalent to the capacity of water in your heater through the water heater outlet.
• Reconnect the water heater’s cold-water inlet pipe and open the valve to fill the tank. Leave the water to sit in the tank for at least 2 hours. The hydrogen peroxide degenerates into oxygen gas and water, so it is safe. However, open all the hot water taps in your home and let the hot water to run off while ensuring that you have shut off the cold-water inlet valve.
• After the tank is empty, then re-open the cold-water valve and fill the tank. Leave the water to sit for at least 15 minutes but leave the hot water taps open to purge out the air from the pipes.
• Turn on the manual switch or the gas control knob and ensure that the water heater is working correctly.


The above procedure will manage the problem of a smelly water heater anode as well as the tank. Since you still have the same water source, repeat the sanitization process with the hydrogen peroxide whenever you smell a hint of a foul smell in your hot water. However, you can also replace the water heater with one that has a plastic lining in the water tank or a stainless steel tank. There is a more costly solution, which involves the use of a tank-less heater. These solutions will completely remove the odor from the heater.