BluGabby: Is it code, or is it necessary, to have an actual electric switch next to the Electric Water Heater to turn the water heater on and off.
Not talking about water valves – but an electrical switch?
This would be separate and in addition to the breaker.
As I understand it, the NEC expects large appliances (which your electric water heater is) to have a disconnect that is within sight of the appliance. Within sight means less than 50 feet away. A fuse disconnect would qualify. So would a switch, if it disconnected both hot legs feeding power to the electric water heater. I am assuming your water heater is 240 Volts. Or any similar system of disconnect.
If the disconnect is NOT within sight of the appliance, the NEC expects that the disconnect is capable of being locked in the open position.
Meaning the breaker controlling the electric water heater can be individually locked open. The locking mechanism must also stay in place, even when the lock is removed. (Like on a gate, the hasp that the padlock goes through remains in place, even when the padlock is removed.)
That is my understanding of the NEC. Granted, most of my work is on rooftop AC units, and they all have the disconnect up on the roof, in sight of the unit.
Now, I have never worked on an electric water heater. The only water heaters I have worked on are gas. So take this with a grain of salt.
Some code references and internet citations follow.