OK, lets talk...Heaters and plastic containers holding water are a risk. Put your hand in the nozzle mist from a heated reservoir, and you will find that the temperature rise is not significant.
My water is at 74 degrees without a heater.
It is your time and money, but your water would have to be hotter than hot water tanks are set at to obtain a significant rise in mist temperature.
Fill a spray bottle with a fine mist setting with hot water, and spray your hand, the temperature of the spray will be much less than the water temperature in the bottle.