Pete in comparison to South Africa you come from a very wet country. We are used to saving water as there was a drought around every corner, however I still like a decent shower to get all the pollution off me! As we live in our touring caravan more or less on a permanent basis an additional water heater would be beneficial. At the end of the day you probably would not be using any more water than normal, but the wife can shower straight after you without having to wait half an hour.