Copper in Drinking Water
Like lead, copper usually comes from your pipes rather than the source. Small amounts are harmless and even necessary, but higher levels cause stomach upset and signal corrosive water.
Copper is an unusual entry on a list of water contaminants because the body actually needs a little of it. The concern is not trace copper, which is a normal nutrient, but elevated levels that come from your own plumbing corroding into the water. Copper and lead are regulated together under the same EPA rule precisely because both are picked up from pipes rather than the source.
What copper is
Copper is a metal widely used for water pipes. At high concentrations it gives water a metallic, bitter taste and can leave blue-green stains on sinks, tubs, and fixtures. Those stains are a useful visible clue that copper levels may be elevated and that your water may be corrosive.
Where it comes from
Copper leaches from copper pipes and brass fittings, especially when the water is corrosive (low pH or low mineral content), when it sits in the pipes for hours, or in newer copper plumbing that has not yet developed a protective mineral coating. Hot water and standing water both raise copper levels, which is the same pattern seen with lead.
The health effects
Short-term exposure to high copper causes nausea, vomiting, stomach cramps, and diarrhea. Long-term exposure to very high levels can damage the liver and kidneys, and it is a particular concern for people with Wilson’s disease, a rare disorder of copper metabolism. For most people, the acute stomach effects are the practical risk, and they appear well above the regulated level.
The EPA action level
Copper is regulated under the Lead and Copper Rule with an action level of 1.3 milligrams per liter. As with lead, this is a trigger for utility corrosion-control action when too many sampled taps exceed it, not a strict maximum at every tap. Because copper comes from plumbing, the utility’s job is largely to keep the water non-corrosive so it does not dissolve metal from pipes.
How to reduce it
The same habits that limit lead limit copper: run the tap until the water turns cold before drinking if it has been sitting, and use cold water for drinking and cooking. If stains or taste suggest a problem, a water test will confirm it. For removal, reverse osmosis is effective at taking out dissolved copper, as covered in our reverse osmosis guide. Persistent copper problems often point to corrosive water, so addressing water chemistry, sometimes with a treatment device that raises pH, is the longer-term fix.