re: hard water: your dishwasher has a setting for that. Set it correctly and make the dishwasher salt compartment isn't empty and your dishwasher will deal fine with hard water.

This is a geographical difference. North American market dishwashers don't typically have that; people use whole-dwelling water softeners that feed all washers (including human).

I don't think I've seen salt compartments in dishwashers in North America.

Water softeners aren't actually standard issue in all dishwashers, but if you're replacing your dishwasher it isn't hard to find one with that feature.