One 16-ounce bottle of Dr. Willard’s Water® DARK™ Concentrate. Dr. Willard’s Water® DARK™ Concentrate contains about half the patented catalyst of the CLEAR™ Concentrate. However, the DARK™ contains fossilized organics (activated carbon, amino acids, readily available trace minerals and other desirable ingredients obtained from lignite). The DARK™ must be diluted according to instructions to ensure maximum effectiveness: Add two liquid ounces (four tablespoons) of Dr. Willard’s Water® DARK™ Concentrate to one gallon of distilled, spring, filtered or tap water. Do not use carbonated water.