Polar Pure water disinfectant destroys water-borne pathogens including Giardia cysts and micro-organisms that may pass through filters. Directions and thermometer on bottle shows the dosage to use. Long-lasting – iodine crystals and solution won’t deteriorate with temperature, age or exposure to air. Ideal for camping, backpacking, bicycling, boating, and emercency kits . Measure dosage in the bottle cap. Treats up to 2000 quarts of water, at less than ½ ¢ per quart.