Water heater anode rod deterioration

While discussing the opportunity of adding water softeners to our product mix our plumbers brought up a concern.  They believe homes with softened water erode the anode rod in the water heater at an accelerated rate which therefore must mean softened water is bad for the home and appliances.  Does this occur?

Answer:  The purpose of the sacrificial anode in your water heater is to promote corrosion of the anode (through galvanic action) rather than corrosion to the water heater tank lining.  Softened water can lead to accelerated corrosion of the anode (under some circumstances, and only when very/zero soft) – but a water softener removes calcium, magnesium, and iron – materials that can lead to water heater failure.  Residential softened water is generally not “zero soft”, and contains a low level of hardness, enough hardness to prevent problems from occurring.  The benefit of using softened water to extend appliance life and prevent build-up of scale deposits on piping and fixtures far outweigh this concern.

By the way, it is important to inspect the condition of the anode every two years whether a water softener is used or not (this is normally mentioned in a water heater manual as part of a regular maintenance schedule).  If the anode appears to be significantly deteriorated, then replacing it is recommended.

Thanks for the information.  Is there a scientific explaination as to why soft water would accelerate the deterioration?  My plumbers would by in better if I can tell them the why and how.

Comments

  1. bparkinson says:

    Thanks for the information. Is there a scientific explaination as to why soft water would accelerate the deterioration? My plumbers would by in better if I can tell them the why and how.

  2. A sacrificial anode’s life depends on the quality of water, the amount of use the tank gets, the water temperature, and the quality of the tank. When salt is added to the water (as in softened water) the rate of galvanic action is increased, and the anode can corrode more quickly. This is why residential water softer designs do not soften to zero – there is always a little residual hardness – and this small amount of hardness prevents corrosion from occuring too quickly. Hope this helps!

Add Comment Register

Speak Your Mind