Even though Zinc is nontoxic to human beings, concentrations above 5 mg/L (ppm) can cause a bitter, astringent taste. This level of zinc can result in a milky, iridescent color in alkaline waters and irritate the human digestive system. Zinc in low quantities, however, is a beneficial and essential element necessary for body growth. In fact, US drinking water contains an average of 1.33 mg/L (ppm) of zinc. Zinc is normally introduced into drinking water through industrial effluents, especially due to dezincification of brass and deterioration of galvanized iron. In addition to drinking water, zinc is measured in surface finishing, boilers and cooling towers, water conditioning, effluent waters and many other applications.