[retiredguy123]

My water heater is a Rheem electric water heater. Here is the recommendation by Rheem as quoted from their manual.

Vacation and Extended Shut-Down
If the water heater is to remain idle for an extended period of time, the power and water to the appliance should be turned off to conserve energy and prevent a build-up of dangerous hydrogen gas. The water heater and piping should be drained if they might be subjected to freezing temperatures. After a long shut-down period, the water heater’s operation and controls should be checked by qualified service personnel. Make certain the water heater is completely filled again before placing it in operation.

The manual also "suggests" that a few quarts of water be drained from the water heater "every month". I don't do this, and I wonder if anyone does this every month. In my opinion, I don't think it is a good idea to open and close the drain valve because it may start to leak.

I could not find anything in the Rheem manual that recommends draining or flushing the water heater as a routine maintenance item.