Copper is an element naturally present in the environment and is an important trace nutrient necessary for human health. Elevated levels of copper are common in home water systems, particularly in residences with copper plumbing. The issue arises when this metal leaches from the pipes into the water supply, leading to concentrations that far exceed nutritional needs. While small amounts are beneficial, excessive copper ingestion from drinking water is a significant health concern.
Understanding How Copper Enters the Water Supply
The primary source of copper in drinking water is the corrosion of internal household plumbing, including copper pipes, fittings, and brass fixtures. Copper leaching originates almost exclusively within the home’s distribution system, unlike contaminants that enter the water source. This dissolution occurs when the water chemistry is corrosive to the metal surfaces of the pipes.
Water with a low pH (acidic) accelerates the chemical reaction that causes copper to dissolve. Water with low alkalinity, its capacity to neutralize acid, also contributes to this corrosive environment. High water temperatures can further increase the rate at which copper is released.
The length of time the water remains stagnant inside the plumbing is a significant factor. When water sits in the pipes overnight or during the day, copper ions accumulate in the standing water. This “first-draw” water, the first to come out of the tap after a period of non-use, typically contains the highest concentration of leached copper.
Visual and Taste Indicators of Excess Copper
Before professional testing, a homeowner may notice several sensory and aesthetic indicators of elevated copper levels. The most common sign is a distinct, unpleasant metallic or bitter taste in the water. This change in flavor can become noticeable when copper concentrations are in the range of 1 to 5 milligrams per liter (mg/L).
Another visible clue is the presence of blue-green stains on plumbing fixtures, such as sinks, bathtubs, and toilets. These characteristic stains are caused by the deposition of copper salts that form as the copper-rich water evaporates. The discoloration may also appear on clothing after laundering, indicating high levels of the dissolved metal in the wash water.
Health Effects of Elevated Copper Levels
Copper is an essential trace element; the body requires a small amount, approximately 2 to 3 milligrams daily, to support various biological functions. However, copper can act as a toxic heavy metal when consumed in excess. High levels of copper in drinking water can manifest in both acute and chronic health effects.
Acute exposure, often from a single instance of drinking water with very high concentrations, typically results in gastrointestinal distress. Symptoms include nausea, vomiting, abdominal pain, and diarrhea. These effects are generally observed when copper levels exceed approximately 3 mg/L.
Prolonged exposure to excessive copper can lead to more severe chronic health issues, particularly affecting the liver and kidneys. Individuals with genetic conditions, such as Wilson’s disease, are especially sensitive because their bodies cannot properly excrete the excess metal. Infants and young children are also a sensitive population due to their developing metabolic systems and higher absorption rate.
The Environmental Protection Agency (EPA) established an Action Level for copper in drinking water at 1.3 mg/L. This regulatory standard, part of the Lead and Copper Rule, is a trigger for corrective action, not a maximum contaminant level. If copper levels exceed this concentration in more than 10% of customer taps sampled, water systems must implement measures to reduce corrosion.
Immediate and Long-Term Reduction Strategies
Immediate steps can be taken to reduce copper exposure from drinking water in the home. The simplest strategy is to flush the cold water lines before use, particularly first thing in the morning. Running the cold water tap for 30 to 60 seconds draws fresh water from the main supply, clearing the copper-rich water stagnant in the internal plumbing.
It is advisable to only use cold tap water for drinking, cooking, and preparing infant formula. Hot water systems dissolve copper more readily than cold water, resulting in higher concentrations at the hot water tap. The water used for consumption should always be the coldest available.
For a permanent solution, professional water quality testing is necessary to confirm copper levels and determine the water’s corrosive properties. Long-term mitigation involves addressing the root cause of the corrosion through water chemistry adjustments. Public water systems may employ corrosion control techniques, such as adding orthophosphate or adjusting the water’s pH, to help form a protective coating inside the pipes.
Homeowners can also install certified water treatment systems to filter out copper at the tap. Point-of-use filters, such as those utilizing reverse osmosis or ion exchange technology, are effective at reducing copper to below the EPA Action Level. These systems provide a reliable barrier against copper and other heavy metals.