SilverDyne® is a natural, silver-based, stable, non-toxic, odor- and taste-free liquid, that when used as directed disinfects water. A 30 ml bottle contains about 600 drops of SilverDyne®, producing roughly 150 gallons of pure water. Most of us use 1 gallon of water a day for drinking and 1 gallon of water a day for cooking. That's 8 gallons a day for a family of four. This half case of 30 ml bottle will last about 12 weeks, or about three months.