If your drinking glasses appear to have a cloudy residue, chances are it was caused by the hard water in your dishwasher. Fortunately, if it's caught early, the residue can be removed and you can enjoy crystal clear glasses again. However, if the residue becomes etched into the glasses, it's too late. Hold up the glasses in the light and look for shades of purple, blue, pink or brown. These are signs of etching, and while you can try to remove the cloudy residue, know that it is likely permanent. Therefore, as soon as you notice just a hint of cloudiness, remove the residue and make some changes to prevent it from happening again.
Fill a container such as a dishpan with undiluted white vinegar and submerge your glasses.
Soak the glasses in vinegar for 15 minutes. Rinse the vinegar and cloudy film off under warm running water.
Wash your glass using hot, soapy water and a soft dishrag. Dry the glasses with a clean, soft and lint-free rag.
Prevent a cloudy residue by adding a rinse additive in your dishwasher and using the correct amount of dishwasher detergent as listed on the detergent's label. Also, if your dishwasher doesn't have a boost heat, set your hot water to 60 degrees Celsius.
For fine glassware that is cloudy due to age, fill the glass with water and add a denture tablet.