July 13 2018 2Comments
Hot Water Anodes

Hot Water Heater Anodes

(Last Updated On: July 13, 2018)

Water heaters are made of metal and as we know, water plus metals equal rust. A water heater that has rust and corrosion will drastically shorten its lifespan. Additionally, the hot water speeds up the corrosion process. So, how do we prevent this from happening and extend the lifespan of the heater? – With a water heater anode!

Hot Water heater anodes
Hot Water heater anodes half way through their lifespan, at 50%


What are anodes and what do they do?

An anode rod is a steel core wire surrounded with one of three different metals. These metals include aluminum, magnesium, and zinc. The rod is screwed into the top of your water heater and protects your water heater from rusting. When the tank is filled with water the anode rod sacrifices itself to protect the exposed steel of the water heater, through a method called electrolysis. During this process the less reactive metal will corrode over the more reactive metal. I.e. the anode rod will corrode before the hot water tank does!

The metals used for anode rods are aluminum, magnesium, and zinc. Which are all much more corrosive than steel – hence why they are used for anode rods. The majority of anodes used in Australian hot water tanks are made of magnesium.


Did you know – having your anode rod replaced can double the life of your hot water system!


How long do anodes last in a hot water system?

Old vs new water heater anode
New vs Old water heater anode

Anodes last up to 5 years and should be checked and if needed, replaced by a licensed plumber during your water heaters service, every 5 years. If you have particularly hard water (which is a water with high mineral content), then it should be checked every 3 to 5 years. Hard water, due to its mineral content, can make the anode rod corrode faster, which also means that your hot water units’ lifespan can be shortened.

Along with the anode replacement during the hot water tank servicing, it’s also recommended that the pressure and temperature relief valve is replaced. Hot water units generally speaking, have a life span of 8 to 12 years. But with regular servicing and maintenance, you’d see it lasting more towards the 12 year mark.


If you’re not sure how old your hot water unit is or indeed if the anode needs replacing, give RTL Plumbing a call and we’ll come out to inspect! Call us now 07 3399 2203




  1. How does this compare to the element that needs replacing?

    Are these rods in a solar tank?

    1. Hi Colleen, they are in a solar tank as well and are different to the element. The element should be checked alongside the anode rod with your service. Hope that helps!


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