Copper is a reddish metal that occurs naturally in rock, soil, water, sediment, and air. Levels of copper found naturally in ground water and surface water are generally very low; about 4 micrograms of copper in one liter of water (4 ug/1) or less. However, drinking water may contain higher levels of a dissolved form of copper. High levels of copper occur if corrosive water comes in contact with copper plumbing and copper-containing fixtures in the water distribution system. If corrosive water remains motionless in the plumbing system for six hours or more, copper levels may exceed 1,000 ug/l. The level of copper in drinking water increases with the corrosivity of the water and the length of time it remains in contact with the plumbing. Water can be a significant source of copper intake depending upon the geographic location, water character, water temperature, and the presence of copper pipes. At concentrations above 1 mg/l, copper can stain laundry and plumbing fixtures. Copper can also cause a greenish/blue tint to blond hair. Copper is an essential element at lower levels but levels above 5 mg/l can cause gastrointestinal disturbances or other acute toxic effects. The recommended treatment method for reducing copper in water is Distillation or Reverse Osmosis.