Copper is a metal that enters tap water from plumbing pipes and natural deposits. In high amounts, it can cause stomach and intestinal distress, liver damage, and anemia.

Copper naturally occurs in rock and soil, and is widely used in plumbing materials. It can enter drinking water through corrosion of copper pipes, especially in homes with acidic water. The EPA regulates copper levels, requiring water systems to test for it. While copper is essential for health in small amounts, excessive intake can lead to health issues. To reduce exposure, run taps for a minute before use, especially after water has been sitting in pipes for several hours.