Fill the hot water pot with water that is warm but not hot or boiling.
Add half a cup of distilled white vinegar to the water. Allow the vinegar-and-water mixture to sit in the pot overnight.
Pour the mixture out of the hot water pot. Check for any remaining lime deposits.
Fill the hot water pot with a fresh mixture of vinegar and water if there are still lime deposits. Scrub away the lime deposits with a sponge or soft cloth.