Monday, April 27, 2015

Replacing the anode rod in my hot water tank to extend its life

Note, this is a revised re-post from my old blog that is now off-line. 

Every three months I connect a hose to the bottom of my water heater and drain a few gallons into a white bucket to remove gunk and the debris that comes off the sacrificial anode rod as it slowly dissolves. The purpose of this anode rod is that it dissolves through a process of electrolysis, and by doing so prevents the walls of the tank from rusting out.  Today, I decided to replace this anode rod, because when I drained water earlier I was seeing rust in the water which is a danger sign that the walls of the tank may be rusting out.  Here is a picture showing how it is installed in a standard electric water heater tank:
It is clearly visible at the top of the water heater tank as the only large nut on the top. 

Below is a picture of a brand-new rod, and below it what was left of the one that I replaced:
New anode rod
worn out anode rod
Clearly it had done its job, and I am concerned that the walls of my tank may have begun to rust.  I had to borrow a neighbors half inch ratchet wrench, and purchase a 1 1/8 inch socket.  He helped me by bracing the tank while I used the ratchet wrench with a six-foot pipe extension to break loose the old rod.  Fortunately the whole replacement process went fairly easily, all we had to do was shut off the water pressure and drain a little water out of the tank by opening the drain and the P/T valve at the top to allow air to enter before removing and replacing the rod.

This water tank has been in service for six years as my solar hot water storage tank, and another six years prior to that it was my primary source of hot water.  This should serve as a cautionary tale to anyone with a water heater tank.  It is a lot less expensive to replace the anode rod than it is the entire water heater!  I got mine at a local plumbing supply store for about $65 -  compared to at least $300 for the cost of the water heater not including labor, this is a bargain.

Note: due to the low ceiling height clearance, I installed a flexible rod like the one below.  
Generally they are straight and measure 24″ to 36″ long, and some are even longer.  Your anode rod needs to be sized to match your tank.

This is part of my ongoing series that deals with the concept of repairing rather than replacing as a way of living sustainably.  One can argue that living sustainably can save you a great deal of money over the long term, and this has certainly been true for my lifestyle.

 NOTE: The tank finally sprang a leak on July 18, 2015 and I replaced it. More about that here.


  1. Great work. Great short and clear write up. Your blog is a pleasure to read, enlightening and inspiring. Greetings from Australia.

  2. Your post on water heater anodes made me wonder why anodes dissolve if the tanks are "glass lined". I found the following Rheem pdf that improved my understanding of a heater's porcelain lining and the accelerated anode decay when used with water softeners. In addition, apparently some anode / water combinations can create a "rotten egg" smell in water requiring a different anode or clorine injection. Finally, the pdf provides Rheem's anode replacement detail.
    Rheem Anode Instructions

  3. rj,
    Thanks for finding the Rheem Instructions! Very informative and helpful.


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