Hard Water Dishwashers
From the mouth of a dishwasher repairman...
"GE is good but noisy, Whirlpool (Kitchenaid) is good only if it has the HE filter in the bottom, Bosch is also very good (expensive but few problems). The chemical mix is what makes the cleaning good or bad"
It really is all about the chemical composition of the water and having a genuine water conditioner (and not a water softener or magnets) makes all the difference in the world. Check out the Best Hard Water Solution.
Dishwasher Repair Tips
Don't believe all the dishwasher detergent hype or instructions - test amounts for yourself.
Water softeners can be illegal in some states.
Only a water conditioner (either fitted to the dishwasher or the whole house) can provide the best protection against hard water, and clean your dishes perfectly.
Use citric acid not vinegar to clean.
What Causes Spots?
When the dry weather causes the water table to lower then the minerals in the water become more concentrated. A higher concentration of minerals = hard water! And hard water causes spots on your glasses & dishes!