Avoid electric shock caused by short circuit in the water heater by proper grounding.

Avoid electric shock caused by short circuit in the water heater by proper grounding.
To prevent the risk of electric shocks resulting from electric contact with the water inside the heater due to damage of the heating element or leakage of water which gets contact with the electrical parts, and as a plastic pipes or isolated metal pipes are commonly used, therefore there is no path to ground for the heater, so be sure to establish the condition of the grounding (Earth), and make sure to connect the wire grounding (Earth) in the body of the heater properly and tightly or follow the manufacture recommendations. If extra precaution is required you can connect the earthing cable to both heater outlet and inlet metal pipes.
The circuit breakers and earth leakage circuit breaker (RCCB or GFCI) do not work correctly if the ground (Earth) wire is not connected, and the safety rating for the heater user becomes poor.
The circuit breakers in this case might work only if the short is live to neutral but not live to casing or ground as there is no earth path.
The earth leakage circuit breaker (RCCB or GFCI) might disconnect only after the electric shock already taking place and depending on the sensitivity and current setting with no guarantee how fast this will be.
Some who work to connect the heaters cut off the ground (Earth) or do not install it well.
The human body's resistance to the current is very high compared to the grounding (Earth) wire. Therefore, if the grounding (Earth) system is properly installed, the current will pass through the grounding (Earth) during the electrical fault and the user is safe and at the same time the circuit breakers or earth leakage circuit breaker (RCCB or GFCI) will automatically disconnect the power.
Switching of the heater before using is good idea for extra precaution but taking in consideration how practical to keep switching of the heater every time you need to use the water, and the electrical leakage is not only affecting that particular heater but maybe the other closer water pipes and outlet in the hose.
Therefore the proper electrical installation is the permanent solution.