Metals

Metallic elements such as cadmium, chromium, copper, arsenic, lead, mercury, nickel, and zinc can be found in water. All are necessary for life, but some ( for example, lead and mercury) accumulate in animal fats and tissues and, in high concentrations, can cause poisoning of the directly exposed organism or concentrate in other species higher in the food chain, including humans. Lead can no longer be used in plumbing in the United States and Australia, and authorities limit the amounts of various metals discharged by industries through federal source control regulations.