Fresh water consumption on a yacht is always more than you expect. A medium-sized yacht has perhaps 350 litres. Sounds a lot and with 2 on board, you're probably OK for a week. Make that 4, or even 6 and filling the tank becomes quite an issue, and it can be expensive, notably in Italy or difficult to find as in Greece in late summer. If you are going offshore, the whole question is quite different, and a water maker becomes pretty much a necessity.
You can connect our units to one of our controllers so that it comes on when a tank is less than half full.