Burning coal

So I had this thought this morning whilst showering.  I try to make them short because they consume so much energy.  Think about it.  To heat one liter of water 1°C it takes over 4000 Joules of energy, most water starts off at about 5°C and most water in showers is over 45°C, so that is 160,000 Joules per liter and most showers use more than one liter of water, much more really. 

So here is my thought, I have just used millions of joules of energy to heat water to have a shower and the water has just gone down the drain.  What if the water went somewhere else, like in the winter it went into the floor and radiated the heat into the house.  After or instead of it went into pipes beneath the sidewalk and the driveway and the heat was used to melt the snow and ice.  To prevent freezing of the pipes it could store the hot water in a bath and have the pipes enter the bath filled with an antifreeze liquid.

My point is we use energy to heat water for one purpose and then throw it away.  We might as well have power plants burning coal producing just smoke and hot air.

What if the hot water was used to pre-warm the water to be heated for the shower or the dishes or the wash.  Sounds sensible, eh!