Things You'll Need
White distilled vinegar
If the interior of your cooking pot has a white chalky residue or ring, it probably has a calcium deposit. Calcium deposits typically occur when hard water sits in the pot for any length of time. Even washing a pot in hard water, and allowing it to air dry can leave behind calcium deposits. Hard water has a high concentration of minerals, such as magnesium and calcium. When exposing a surface to mineral rich water, calcium deposits can remain on the surface after removing the water. To avoid calcium deposits, dry the pot immediately after washing, and don't allow water to sit for an extended time in the pot.
Combine equal parts white distilled vinegar and water in the pot.
Place the pot on the stove burner and bring to a boil.
Remove the pot from the burner and allow it to set for about 24 hours.
Pour out the vinegar water solution and scrub the stained area with a nylon scrubber dipped in vinegar, if any residue remains.
Wash the pan in soap and water and dry.