Hi Wlhcon1:
The anode rod has nothing to do with the volume of hot water available to the house.
The reason an anode rod is used with hot water heaters is to act as a point of SACRIFICE for the water heater. Here, instead of the anions and cations (charged particles) in the water supply attacking the tappings of the water heater they will interact with the anode rod and precipitate out of solution (usually as a salt) and deposit onto the floor of the heater. It is this precipitate that ends up being an issue and it is for that reason that you flush the water heater periodically...to remove sediments and the precipitate(s) that have formed.
Eventually the anode rod will get used up and the charged particles will start to attack the tappings of the water heater. This will quickly lead to a leaking water heater and the need to replace it.
If you have a particularly HARD WATER then you may want to change out your anode rod every 4-5 years. You would need a 1-1/16" or 1-1/8" socket and a 1/2" drive ratchet and a friend to help you remove the old rod. It would definitely increase the life of your heater...
Let us know if you would like to discuss this further...glad to help.
MARK
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