Hey we get actual cold tap water... sometimes... once or twice a year. Yeah I guess it's different for you guys, in AZ most of the time your waterheater can keep up with you for home use.
It's interesting becase ironically, you live in the land of the eternal sun, but we are the ones who need to use technology to collect the sun's warmth. Because it's cold!
For example, if you have to heat up ground water at 45-50 degrees to heat a house through a base-pipe heating system, it takes a lot of oil, but if the water has been halfway-warmed up to 60-70 degrees, it takes a lot less fuel to heat it enough, or at all, to heat the entire house.