J.CROW'S LUGOL'S SOLUTION 2% is solution used as a water purifier. It is made from premium ingredients, the iodine used in J.CROW'S Lugol's Solution is derived from mined crystals from 320 million year old natural brine deposits two miles beneath the earth's surface in Western USA (one of the few places in the world where such deposits exist). Not made from shellfish. The water used is distilled, pure, New Hampshire spring water. Always fresh. Does not expire. Store at room temperature out of direct sunlight. No need to refrigerate. Be safe. Accept no substitutes. To use as a water purifier add 3-6 drops per liter of water.