Copper has long been associated with water, with traditions across cultures suggesting its ability to purify. This ancient practice sparks curiosity about the scientific basis behind copper’s potential to keep water clean. Understanding its unique properties provides insight into its effectiveness and safety in both historical and contemporary applications.
How Copper Cleans Water
Copper’s ability to clean water stems from a phenomenon known as the “oligodynamic effect,” where small concentrations of metal ions exert a toxic effect on living cells. When copper comes into contact with water, it releases positively charged copper ions, primarily Cu2+. These ions are highly reactive and target microorganisms through multiple mechanisms.
One primary way copper ions act is by damaging the cell membranes of bacteria and fungi. They interact with the negatively charged components on the cell surface, causing the membrane to rupture and vital cellular contents to leak out, leading to cell death. Copper ions also generate reactive oxygen species (ROS) within microbial cells. These highly reactive molecules cause oxidative damage to lipids, proteins, and DNA, impairing essential cellular functions.
Beyond membrane and oxidative damage, copper ions interfere with the internal machinery of microbial cells. They can bind to and denature proteins and enzymes, disrupting their three-dimensional structure and preventing them from performing their normal functions. Copper ions further damage the genetic material, fragmenting DNA and RNA, which prevents replication and ultimately leads to the inactivation or death of the microorganism. This multi-pronged attack makes it challenging for microbes to develop resistance to copper.
What Copper Affects and Its Limitations
Copper exhibits antimicrobial properties against a range of microorganisms, including various bacteria such as E. coli, Salmonella, and methicillin-resistant Staphylococcus aureus (MRSA). Studies indicate that copper surfaces can kill over 99.9% of these bacteria within minutes to a few hours. Copper is also effective against certain viruses, including influenza A, SARS-CoV-2, and norovirus, as well as fungi like Aspergillus and Candida.
However, copper is not a universal water purification solution.
Copper does not remove chemical pollutants from water, such as pesticides, industrial chemicals, pharmaceutical residues, or organic compounds. It also fails to eliminate common water contaminants like chlorine or fluoride. Furthermore, copper does not filter out heavy metals, sediments, or larger particulate matter.
Practical Use and Safety of Copper in Water
Copper has been used for centuries in water systems, with historical practices including storing water in copper vessels, particularly in Ayurvedic traditions. In modern applications, copper is a common material for plumbing pipes and is incorporated into some water filtration systems due to its antimicrobial benefits. Its use extends to high-touch surfaces in healthcare settings to reduce microbial contamination.
While copper is an essential trace element, excessive intake can lead to toxicity. Symptoms can range from gastrointestinal distress (nausea, vomiting, diarrhea, stomach cramps) to more severe issues like liver and kidney damage. Neurological symptoms such as headaches, dizziness, fatigue, and irritability can also occur.
Regulatory bodies have established guidelines for safe copper levels in drinking water. The U.S. Environmental Protection Agency (EPA) sets a maximum contaminant level (MCL) of 1.3 milligrams per liter (mg/L) for copper in public drinking water systems. The World Health Organization (WHO) suggests that adults should not exceed 0.47 mg of copper per kilogram of body weight per day. Copper levels in water can increase due to corrosion from copper pipes, especially with acidic or hot water, or if water sits in pipes for extended periods.