In some countries, electric showers use a metal coil as a heating element, similar to a spring, located directly in the showerhead. When you turn on the faucet,

In some countries, electric showers use a metal coil as a heating element, similar to a spring, located directly in the showerhead. When you turn on the faucet, water fills the showerhead and touches the metal, effectively bringing the positive and negative wires into contact. The coil then heats the water as it flows out. Occasionally, the coil can oxidize or break if there's not enough water running to keep it cool. When that happens, most people replace it themselves.