For centuries, people have explored various methods to ensure their drinking water is safe and clean. Copper has a long history of use in water storage and purification, with ancient civilizations from Egypt to India storing water in copper vessels. This historical practice often leads to questions about copper’s ability to truly purify water and make it safe for consumption today.
How Copper Fights Microbes
Copper combats various microorganisms through a phenomenon known as the oligodynamic effect. This process involves the release of tiny copper ions that interact with microbial cells. When bacteria, viruses, or fungi contact copper, these ions interfere with their fundamental biological mechanisms. Copper ions damage cell membranes, creating holes and compromising microbial integrity. This disruption leads to leakage of essential cell nutrients, causing desiccation and ultimately cell death.
Beyond membrane damage, copper ions also target and disrupt proteins and enzymes crucial for microbial survival. They can alter the three-dimensional structure of proteins, rendering them non-functional, and bind to sulfur- or carboxylate-containing groups, inhibiting enzyme activity.
Furthermore, copper can generate reactive oxygen species, leading to oxidative stress that damages lipids, proteins, and even the DNA or RNA of microorganisms. This multi-pronged attack explains copper’s effectiveness against a broad spectrum of pathogens, including bacteria like E. coli, MRSA, Salmonella, and Vibrio cholerae, as well as various viruses and fungi. Studies show copper surfaces can inactivate over 99.9% of certain bacteria within minutes to a few hours, outperforming materials like stainless steel.
What Copper Cannot Remove From Water
While copper demonstrates notable antimicrobial properties, it has limitations as a water purification method. Copper’s action is primarily directed against biological contaminants such as bacteria, viruses, and fungi. It does not effectively remove a wide range of chemical pollutants present in drinking water. For instance, copper will not eliminate heavy metals like lead or arsenic, which can pose severe health risks.
Pesticides, herbicides, and chlorine, commonly found in municipal water supplies, are also not removed by copper. Copper does not address physical impurities such as sediment, rust particles, or dissolved solids that can affect water clarity and quality. Nor does it inherently improve water’s taste or odor, which can be influenced by various chemical compounds. Therefore, relying solely on copper for water treatment would leave many common and potentially harmful contaminants unaddressed, making it an incomplete solution for comprehensive water purification.
Safe Copper Levels for Drinking Water
Copper is an essential trace element for human health. However, consuming copper in excessive amounts can lead to adverse health effects. Short-term exposure to high levels of copper in drinking water can cause gastrointestinal distress, including nausea, vomiting, diarrhea, and stomach cramps. Prolonged exposure to elevated copper levels can result in more severe issues, such as liver damage, kidney disease, and in some cases, damage to red blood cells or neurological problems.
Certain populations are particularly sensitive to copper toxicity, including infants and individuals with specific genetic disorders like Wilson’s disease, as their bodies have difficulty regulating copper levels. Regulatory bodies establish guidelines to ensure safe copper levels in drinking water. The U.S. Environmental Protection Agency (EPA) sets an action level of 1.3 milligrams per liter (mg/L) for copper in drinking water, equivalent to 1300 micrograms per liter (µg/L) or 1.3 parts per million (ppm). Exceeding this level triggers corrective actions for water systems. The World Health Organization (WHO) also provides a provisional guideline of 2 mg/L for copper in drinking water.
The primary source of elevated copper in drinking water often comes from the corrosion of household plumbing, particularly from copper pipes and brass fixtures, especially when water is stagnant, acidic, or hot. Running the tap for a short period, especially after water has been sitting in pipes for several hours, can help reduce copper concentrations.
Real-World Uses and Important Considerations
Copper’s antimicrobial properties have led to its practical application in various water systems. Copper piping is widely used for water supply and distribution in buildings due to its durability, corrosion resistance, and ability to inhibit bacterial growth within the pipes. Beyond plumbing, copper is historically recognized for its role in water storage vessels, with ancient cultures utilizing copper pots to keep water cleaner. Modern water purification systems sometimes incorporate copper, such as through “active copper technology” or copper-silver ionization, to leverage its germ-killing capabilities.
Despite these applications, copper is not a comprehensive water purification solution. For its antimicrobial effect to work, sufficient contact time between copper and the microorganisms is necessary, ranging from minutes to several hours depending on the pathogen and copper concentration. Therefore, for unknown water sources or for ensuring broad-spectrum purity, copper should not be the sole method of water treatment. Combining copper-based solutions with other purification technologies, such as filtration or reverse osmosis, provides a more complete approach to safe drinking water.