Perfect Moose Jack will add roughly 10% weight with each cycle, depending on the desired end-temperature. This means for every liter of milk the Jack froths, it uses roughly 0.1 liter of water for steam.
A boiler refresh requires 3.4 liters of water, 2.4 liter is used for mixing with the hot steam during the drain and 1 liter is used for filling the boiler again with water.
WHAT IS THE REQUIRED WATER SPECIFICATION FOR JACK?
You can find the reccomended water specification for Perfect Moose Jack by clicking here.