Skip to main content

How to Tell if Anode Rod is Bad

By December 23, 2020Home Maintenance
How to tell if anode rod is bad

Anode rods are found on standard tank style water heaters and protect the middle lining of the water tank from possible explosion and corrosion.  They are screwed into the top of the tank.  Eventually, they do wear out, but how do you tell if anode rod is bad? 

The water becomes discolored and rusty and the rod is corroded when you open the tank.  There are also other signs such as a rusty smell, sulfuric acid smell (rotten egg smell), and the water heater is making a noise. 

Let’s find out about anode rods, why they are an important part of the water heater, different types, steps and signs to tell if it is bad, different anode materials, what to do when anode rod is bad, tips after replacing the rod, and maintenance.

Why the Anode Rod is Important

The anode rod is an important part of the water tank.  It keeps the middle lining of the tank from rusting, thus changing it every few years is important in order to avoid replacing the entire unit. 

How can you tell the anode rod is bad? Once the rod dissolves, rust gets into the water and the tank is done and needs replacing. It is called “sacrificial” as it loses its life before the water can become corroded.

Type of anode rods
Magnesium anode new and old

Type of Anode Rods

There are four types of these rods and they work best in various situations

Magnesium Rods

Work best with homes with soft water. 

Pro: Most economical. Con: corrodes faster as the soft water is more corrosive so they wear out faster.

Aluminum Rods

Best for homes with hard water and high ph. Cons: likely to split into other pieces.

Zinc/Aluminum Rods

Made up of 10% zinc mixed with aluminum. Pro: good for homes with sulfuric acid smell (rotten eggs).

Electrical Rods

This type is the longest lasting and doesn’t wear down. Pro: They use electric pulses that will get the corrosive elements out of the water in the home. They are non-sacrificial and don’t degrade. Con: Much more expensive (Over $90) for each one

What happens with the anode rod
Inside of a water heater and a corroded anode rod

What Happens With the Anode Rod

The metal used on anode rods are less reactive than those in the steel lining of the water tank and pipes. So the anode rod is sacrificed first before the water tank and pipes.  Over time, the anode rod releases electrons into the water and this helps the metal parts of the tank to last longer.

When the water heater is used more, the anode rod will wear out faster- no matter the type of water in the home.  As mentioned above, water is corrosive and will make the rod wear out faster.

Steps to Tell Anode Rod is Bad

  1. Read the owner’s manual to see if the rod is located at the top of the water heater or near the outlet.
  2. Close the shut-off valve for the water supply.
  3. Go to a tub or sink faucet and turn it on for a minute to allow the pressure to come out.
  4. Shut off the electricity/gas to your water heater.
  5. Grab a bucket and a hose and then attach the hose to the drain valve near the bottom and empty out a few gallons of hot water.
  6. If there is rust or sediment, you may want to consider flushing or draining the tank.
  7. At the top of the tank is the hex head screw that you can remove with a wrench.  Once you have it off, you can access the anode rod.  You may need WD-40 to get the rod off the side of the tank if it is stuck.  Once you get it off, check the condition of the rod.
  8. If the rod is corroded, thin, or missing parts, then it needs replacing.

Continue below to find out how you can replace your Anode Rod.

Signs You Can Tell Anode Rod is Bad

Rusty smell

There is a rusty smell coming from the water. This may be that the rod is bad or is loose and moving throughout the water tank.

Smell of rotten eggs

A smell of rotten eggs is aluminum or magnesium reacting to the water.

Brown or rusty water

If you see brown or rusty water coming out of the faucets, it is a sign there is corroding on the anode rod, and replacing is needed.

Gel-like substance

A gel-like substance coming from the heater can be from the anode reacting with the water. The substance will come out of faucets in the home and you can fix it by changing to a different anode material.

The water heater is leaking

This can be due to a corroded and worn out anode rod and needs replacing.

The water heater is making noises

This can be due to the anode rod is loose and hitting the sides of the water heater or the water heater is breaking down.

The water heater is 5 years old

This is a good time to replace the anode, if you haven’t done so already. Doing this will help you extend the life of the water heater.

Which Material to Choose When the Anode Rod is Bad

When the anode rod is bad, it depends on the condition of your water as to which one to use.  If you have soft water, choose magnesium.  If you have hard water and high ph., choose aluminum.  Lastly, if you have the rotten egg smell, choose zinc/aluminum.  

However, always check the owners manual for the one that is compatible with your tank.

Price Range of Anodes

Magnesium, Aluminum, Zinc/Aluminum rods range from $10-$30

Electrical rods $90 and up

Water heater replacement ranges from $800 into the thousands.

What to Do When the Anode Rod is Bad

When the anode rod is bad, follow the steps below to replace it.  Also make sure to consult your owner’s manual.

  1. Shut off the power, water, and fuel supply.
  2. Locate the anode rod. If it is on the top of the tank, measure the space above the water heater, if there is less than 44-51 inches (the length of a standard anode rod), you need to purchase a flexible rod instead. If you don’t see it, consult the user manual.
  3. Drain some water out of the tank, about 10%.
  4. Take off the hex head screw, remove the old anode rod, and put in the new anode rod. Be sure to use Teflon tape around the threads of the new anode rod to prevent leaks.
  5. Turn on the electricity or gas to your water heater and turn on cold water supply and turn on the cold water.
  6. Open the hot water valve you used earlier and let water flow out so the air escapes.
  7. Check for leaks, turn the power back on.
  8. Make sure that clean and non-smelling water is coming out.
  9. If not, you may need to call a professional to investigate further.

Tips After Replacing the Anode Rod

Take a Picture of the Anode Rod

When you replace the anode rod, take a picture of it before you put it in the water heater.  This will allow you to see how it is doing as time goes on.  You will have a good idea of the stages it goes through so when it is time to replace it again, and you aren’t caught off guard.

Check the Anode Rod

A few weeks after replacing the anode rod, make sure it looks different than when you put it in there. There should be some evidence of corroding.  This will be a good way for you to know that it is working.

Test the water

It is a good idea to test your water just to make sure it is clean for human consumption.  Also, take a look at the reading on the water meter to make sure you aren’t losing more water or have a leak you don’t know about.

Maintenance of the water heater

Maintenance of the Water Heater

Maintaining the water heater is important.

  1. Flush the water heater yearly by draining it
  2. Adjust the temperature and reset.  If it is a gas heater, contact a professional for help, as it is more complex than most people know.  An electrical heater is much easier
  3. Turn your gas water heater off and back on
  4. When traveling, set the water heater to “vacation” mode
  5. Check the drain valve for leaks- if it is leaking, use a wrench to tighten it
  6. Set the thermostat at 120 degrees Fahrenheit

When to Call a Professional

You may need to call a professional for several reasons: When it is difficult for you to check the rod on your own, and you change out the rod and the water is still dirty. Also, there are signs such as those in the maintenance section that may be telling you that there is something wrong with the water heater, water is leaking, smells, or is dirty.


Checking the anode rod to tell if it is bad may be difficult, so contact a professional if you need help.  Maintaining the anode rod is important so the water heater can last as long as possible. Lastly, it is a large expense if the water heater goes out.

Have you used flexible rods before or have preference in one of the material types of anode rods? Maybe you have questions about which type of anode rod to use or need help? Drop us a line below, we would love to hear from you!