Unload the dishwasher of all the dishes, cookware and utensils. Also, remove the utensil holder.
Fill a measuring cup or a dishwasher-safe bowl with 2 cups of white vinegar. Place it on the bottom rack of the dishwasher, face up, according to most LG dishwasher manuals.
Run the dishwasher completely through one normal cycle. LG also recommends selecting the extra rinse or sanitize option. Repeat if the hard water stains are still there.
Moisten a sponge or rag with white vinegar and scrub the inside tub to remove a film caused by hard water or to remove stubborn hard water stains.