I don’t know about you, but I’m not a fan of hearing that ominous dripping or finding the flood of a burst water heater. Thankfully, it doesn’t happen often, and that is largely due to the little accessory known as an anode rod.
Anode rods are self-sacrificing and we can all appreciate this hero of your hot water supply. I would call them essential, even though they technically don’t add to the function of the heater.
Water heaters don’t need anode rods to function, but they help preserve the quality of the water and can double the lifespan of the heater. Without anode rods, a water tank will corrode and leak or even burst. Anode rods are designed to deteriorate, so they need to be replaced in order to remain functional.
Water Heaters Work Without Anode Rods
Water heaters use elements that can heat up to high temperatures to warm water that comes into contact with these elements. Water heaters heat these elements using gas or electricity (and sometimes solar power).
The heaters themselves can have standard storage tanks or be tankless, but tankless water heaters do not have anode rods so, only storage tank heaters will be discussed here.
Important Components and Their Functions
Aside from the essential element that is heated, there are several other components to a water heater:
- The temperature-pressure relief (TPR) valve maintains safe temperatures and pressures in the tank as per manufacturing design. This is done by allowing some water to drain from the tank if the pressure or temperature is too high.
- The drain valve is how water is allowed to drain out of the heater without going through the outflow pipe.
- The metal anode rod sits at the top of the tank and helps purify the water.
- The dip tube is how cold water gets into the tanks for both electric and gas heaters.
- There are water outflow and overflow pipes. The first allows water to enter the pipes that lead to taps when hot water is needed in the house. The overflow pipe prevents the storage tank from becoming too full.
- The thermostat measures heat within the tank.
How Water Is Heated
At the bottom of an electric heater, the thermostat measures the lowering of the temperature in the tank and allows electricity to flow to and heat the element. Once it warms to the set temperature, the electricity cuts off. In dual-element tanks, each has its own thermostat that is independently operated to heat the water.
In a gas heater, the lowered temperature is measured by the thermostat that sends the signal to the gas valve that can only release gas once the thermocouple has confirmed that the pilot light is on. Once the set temperature is reached, the gas supply is cut off.
In both heaters the warmer water will rise, allowing the colder water to fall to the element and be heated.
The Purpose of Anode Rods
Anode rods are metal and are commonly made of aluminum, magnesium, or a zinc or aluminum alloy.
They serve the crucial role of drawing the corrosive substances and any sediments in the water. The anode rod sits at the top of the tank and is designed to draw these substances to itself. In doing so, the rod is corroded and not the metal of the storage tank.
It also helps prevent rusting on your tank that occurs from the combining of steel/iron, water, and oxygen in your water heater. You extend its life by protecting your water heater tank from corrosive substances.
This only applies to glass-lined water heaters. Stainless steel water heaters are corrosion-resistant and therefore do not require anode rods. You can find a detailed comparison of the two types of water heaters in Glass Lined Water Heater vs Stainless Steel: Which is best?
While you have to replace the anode rod as it corrodes, you do not have to frequently replace your whole water heater before it’s time.
An anode rod will need replacing approximately every 3 to 5 years. Which is longer than you think, but definitely shorter than you hope your water heater will last.
How Anode Rods Fulfill This Purpose
According to Gold Medal Service, the anode rod fulfills its purpose by having “a lower, more negative, electrochemical potential”. This is because the more negative voltage a metal has, the more reactive and vulnerable the metal is to damage.
The anode rod is made of metal that is more vulnerable than the steel of the water heater tank.
With the negative voltage, the anode rod will more readily give up electrons, which is how the reactions occur, and so it will corrode instead of the tank. It also protects other important metal components like the heating elements.
When iron or steel (such as the steel used in your water heater tank) loses two electrons, rusting occurs. Magnesium and aluminum let go of their electrons much quicker than metals like iron or steel. Aluminum and magnesium corrode the same way your tank would, but they do it much faster and use up the “ingredients” before the tank has a chance to start.
Once corrosion starts, it triggers a destructive cycle, because corroded metal is compromised and more vulnerable to further corrosion. However, as long as this is happening at the anode rod, it is not happening, or at least not in a significant way, on the surface of your water heater tank.
What Will Happen if the Anode Rod Is Removed?
If the anode rod is removed, all the damage that it would take on will be directed at the metal water tank. Your tank will begin to rust and corrode, and your weakened tank will crack, leak, and eventually burst.
This will happen over a few years, but it will happen. An anode rod has a lifespan of 3 to 5 years depending on the quality of your water and the frequency with which your water heater is used. It is a lot cheaper to replace the rod.
There are some signs that indicate your tank is corroding:
- Water can be a coppery color due to the rust residue.
- Water from the tank may look cloudy due to sediment building in the tank, which will also take up water space. This can be drained out of the tank but is indicative of problems.
- Water takes on a rotten odor.
- You may hear loud and unusual noises when the tank is heating water, such as popping.
- Water may be colder as the tank cannot heat it properly with damaged components and increased sediment.
It’s also important to know that by removing the anode rod (without replacement), you will likely void the warranty on your water heater. Which means that when your water heater breaks (and it will do so prematurely without the anode rod), your insurance claim will be impacted. This includes any structural or item damage that occurs with it.
Furthermore, if there is a fault in your unit, the manufacturer will not be obligated to replace or repair it if you have removed the anode rod.
How Long Will the Water Heater Last Without Anode Rod?
Your water heater can last 15 to even 20 years with an anode rod and good maintenance. You have to consider factors like how acidic your water supply is and how often the heater runs. However, your water heater should still have a decently long life.
Without the anode rod, it is a very different story. Your water heater is likely to last about 8 years maximum with regular and sufficient maintenance. This is less much less if you have very hard water (probably only around 3-5 years).
So, every decade you are looking at bearing the cost of a new water heater and the damage that a bursting heater causes to your house.
You can buy an anode rod, such as the Kohree Aluminum Zinc Anode Rod (amazon link), for a mere fraction of the hundreds of dollars it costs to purchase a new water heater and install it.