We have averaged in the 2-4 gallons per person per day on passages and offshore and between island cruising. I agree with Gunni's comment about power consumption being a major factor. You have to consider both the gallons per day needed per person, the gallons per hour the watermaker can produce, and the power required to produce the water AND backflush the system after each cycle. You will learn how to conserve water, but having a watermaker certainly makes life easier. We cannot easily get into some marinas, or have to go well out of our way to get to a marina where we can get to the dock to get water. Otherwise, the option is to schlep water in the dink in 6 gallon tanks - a very time consuming process for 50-80 gallons or more. Capta provided some other key considerations. I know some who have modular installations like Gunni mentioned and they seem to work out well for them. If possible, I'd power the thing with solar, along with the fridge. We've been using the generator out of necessity, but hope soon to be converting to DC entirely and take advantage of the free sun energy and fewer moving parts to break down - like our generator that is down currently while waiting for replacement parts...