#6 How does water hardness affect dishwashing?
Hard water can be detrimental to the performance of your dishwasher. Over time, glassware washed in hard water will become cloudy and dishes will become spotted or covered in a white film. Using very hard water can cause dishwasher parts to fail over time.
Naturally soft or softened water has no detrimental effects if used with the correct amount of detergent. However, excess detergent combined with hot, soft water may cause irreversible etching on glassware. Etching first appears as a rainbow-coloured film and — if allowed to continue — can make glassware permanently opaque.