On 17 Mar, 12:21, Rod wrote:

Many, many years ago was there not a Tomorrow's World item on an
electric water heater in which it was implied (or maybe even stated)
that the electricity *did* go directly through the water? I have a
feeling that they laboured the "electricity and water don't mix" in the
lead into the item.

Such electrode heaters do exist, but they aren't used in domestic
electric showers.