Electric Geyser is an advanced version of the above Water heater with additional safety features. This operates on simple principle of cold water in and hot water out. Till date the same Principle is used by countless manufacturers across the world.
In the last 131 years despite of Technological advancement we are using this design which is not energy efficient. There is a wastage of almost 50% of electricity in this type of water heaters. This is basically due to flow of cold water into the geyser chamber, as we draw hot water. Please watch the below video for easy understanding.