What kind of water do you use to homebrew?

I usually use 2.5 gallons of store bought drinking water and another 2.5 gallons of spring water.
I put one gallon of each in the boil pot for the wort along with half a gallon of tap water to make up for what boils away into steam.
I add the remaining 3 gallons of water into the carboy after the wort is chilled and yeast is added.