Coeur d'Alene publishes one average for city water, so one setting is a reasonable start without a test. The 2025 report rated the water hard at an average of 8.25 grains per gallon, defined hardness as the calcium and magnesium salts in the water, and described chlorine disinfection at each well with no softening step. Its samples ranged from 7.92 to 8.54 grains, close together, so one setting usually fits on city water; check it against your manual's table. The city's Water Quality Reports page carries the current figure.
Water like that can leave white limescale on dishes, the tub, the racks, or the door, as Bosch's troubleshooting guide describes. Three checks follow, in order.
First, the machine's own softening, on dishwashers that have it. Set the softener to the band your manual gives for about 8 grains per gallon; on a Bosch softener model that is H:01, but the table belongs to the model, so check your own. Where there is a salt cap, keep it filled: Miele's instructions say that water above 4 grains per gallon must be softened by the machine's integrated softener, which runs on dishwasher salt, and the city's 2025 average was about double that figure. Many dishwashers have neither a hardness setting nor a salt cap, and the manual says which kind yours is.
Second, the spray arms. Power off at the plug or the breaker first. Bosch's care section tells owners to check the spray arms for grease and limescale deposits, and on its models the upper arm unscrews, and the lower one pulls off for a closer look. Other makers differ, so follow your own manual on how to remove the arms.
Third, rinse aid. Keep the dispenser filled, because Whirlpool says rinse aid can minimize the repeat buildup of white film, and on a machine with no hardness setting it is the main control you have. The same film table's other remedies are a pre-measured quality detergent pod, a clear path for the spray arms and the detergent door, and a rack that is not overloaded, with dishes loaded at an angle. If the film comes back after all three checks, text or call.