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What Are the Causes of Water Heater Element Corrosion?

Hi Friends,

When a water heater stops producing hot water, the first thing that usually goes bad is the heater elements. The elements are eaten away by the corrosive effects of the dissolved minerals and chemicals in city water. So, by understanding the exact chemical reactions that take place, I cannot understand why the elements corrode to the point of becoming ineffective and what are the causes of water heater element corrosion. Any idea on it, please share with me.

Thanks a lot!

Harry Potterish


  • Zman
    Zman Member Posts: 7,572
    Water heater workbook

    Have you read "The water heater workbook"?  It is available on this site.

    I suspect that the elements are actually the second thing to corrode in your heater. Keeping up with maintenance is the most important part. You should be checking and replacing the anodes regularly.

    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,331
    edited November 2012
    thanks Carl

    If the elements are failing repeatedly, it might be time to try a different type.  Most heaters come with a less expensive element. that has a copper sheath. They also are usually a "high watt density" style.  This forces more heat through a smaller element surface area, speeding corrosion in acidic or aggressive waters.  Elements also come with a stainless or nickle alloy sheath which holds up better. 

    As Carl suggests, do check the anode/s in the heater to make sure "Demon Rust" isn't having a good time in your heater at your expense!

    Yours,  Larry

    ps.  If the elements you're replacing are covered with scale, understand that chemical reactions in general, double their speed with every 20 degree rise in temperature.  Scale on the element slows heat transfer, speeding up damage to that element.
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