as Wineview stated: buy a gallon of distilled water and mix 1.2 teaspoons of starsan. store the solution in that gallon jug with a cap firmly in place. use it to wash a carboy and pour it back into the gallon jug. It can be reused multiple times. Some videos on Youtube state that it can be used for months. I just keep some in a spray bottle.I keep finding stuff on Amazon that's like $10 per one carboy wash