What it is:
• Natural element (symbol: Cu). A reddish, ductile “transition metal” occurring naturally in rock, soil, water, plants, sediment and air.
• Typically dissolved in water as a divalent cation (Cu+2).
• In small amounts, copper is an essential element for living organisms, as a catalyst for producing enzymes.

Occurrence:
• Obtained for many industrial uses by mining of copper ores. Widely used in copper pipe and tubing. Cu compounds also used for pesticides, algae control.
• Natural copper levels in groundwater and surface water: about 4 micrograms per liter (parts per billion) or less.
• Drinking water may contain higher levels of dissolved copper from corrosion of copper plumbing. Level increases with corrosivity of the water and contact time with the plumbing. Possible indicator: blue-green stains on fixtures.
• Can be discharged from wastewater treatment plants. Does not break down in the environment.

Health effects:
• Too much copper can cause gastrointestinal distress, including nausea and vomiting. Long-term excess exposure associated with liver damage, kidney disease.
• US Department of Agriculture (USDA) recommends dietary intake not to exceed 10 milligrams per day (mg/day) for adults.
• Copper is necessary in the diet in small amounts. Recommended intake for adults (USDA): 1.0 to 1.6 mg/day.

Other:
• Corrosion in copper piping/tubing:
Pitting: Pinhole leaks and surface pitting, especially in cold water. More common with: water pH of 7.0 to 7.7, dissolved oxygen exceeding 3 parts per million (ppm), carbon dioxide of 25 ppm or more, sulfate-to-chloride ratio greater than 3-to-1, water containing iron, manganese or aluminum.
Erosion: More common with recirculating hot water (140°F/60°C or more), soft water, high flow velocities, excess pipe burrs and solder globules disrupting laminar flow.

Regulation:
• US EPA Primary Drinking Water maximum contaminant level goal: 1.3 ppm. Secondary maximum (recommended to avoid metallic taste or blue-green staining): 1.0 ppm.

Water treatment:
• Point-of-entry (POE) cation exchange, pH control, film-creating compounds (such as polyphosphates).

• Point-of-use (POU) treatment for leaching after the POE: pitchers (with ion exchange media), reverse osmosis (RO), distillation. Reverse osmosis removes up to 97%. Activated carbon will also reduce copper by adsorption.

• Backflow prevention ahead of carbonated beverage dispensers.