Copper in Our Residential Water Systems: Corrosion and Blue Water

Javed Iqbal  |  3/6/2008 9:16:06 AM

Deposition of blue-green stains on the shower walls, floors and curtains due to copper corrosion byproducts in the bathroom. Copper concentration was 0.01 mg/L in source well water outside the house and 1.064 mg/L in faucet water inside the house. (Photo Courtesy by Sheri Roberts, La.)

ICP-OES spectrum graphs indicating copper concentrations in well water 0.01 mg/L (upper) and shower water 1.064 mg/L (lower). Blue copper stains were also observed on material used in water filtration units

Javed Iqbal, Lab Manager, W.A. Callegari Environmental Center, LSU AgCenter


Copper is a common, malleable metal that occurs in natural deposits as ores containing other elements, soil, water, sediment and air. It is used to make products such as coins, electrical wiring and water pipes for household plumbing. Copper is an essential nutrient, required by our body in very small amounts. In 1974, Congress passed the Safe Drinking Water Act. This law requires EPA to determine safe levels of chemicals in drinking water based solely on possible health risks and exposure that may cause health problems. These levels are called Maximum Contaminant Level Goals. The MCLG for copper is 1.3 milligram/liter (or parts per million). Exposure for short periods above this level may cause gastrointestinal disturbance, including nausea and vomiting. Exposure over many years could cause liver or kidney damage. An action level for copper is also set as 1.3 ppm, which is the lowest level to which water systems are required to control this contaminant should it occur in drinking water at their customers' home taps.

Sources: Copper is widely used in household plumbing materials. Corrosion of plumbing and brass component is by far the greatest concern which cannot be directly detected or removed by the water system. EPA is requiring water systems to control the corrosiveness of their water if the level of copper at home taps exceeds an action level. Low pH (less than 6.5) indicates acidic and corrosive water that can break down the pipes and could cause a higher concentration of copper. Copper corrosion is greatest in very acidic water; however, both low and high pH can cause this problem. Copper corrosion can also occur when a plumbing system is not adequately flushed or is allowed to remain stagnant with residual water for an extended period of time.

Copper mining, smelting operations and municipal incineration may also be sources of contamination.

Improper grounding of electrical service can cause copper corrosion and blue water, causing electrolytic dissolution of copper sometimes referred to as "Blue Water Syndrome". Galvanizing (zinc) and the pipe underlying the galvanized surface (steel) are mostly anodic to copper. These materials go into solution preferentially to copper.

The water pipe that enters the house is normally used to ground the electrical system. A variety of different scenarios can cause a very small electrical charge to be present in the plumbing. This electricity can cause a chemical breakdown of the copper.

New copper pipes usually dissolves at a rate of .001-.003 inch per year during the first few years of installation; more quickly in the first year of usage. Blue water occurs many times in homes which are larger and have only a few occupants or or with water over softened with water conditioner.

Detection of Copper: Elevated levels of copper can be determined by a bitter metallic taste or blue to blue-green stains around sinks, shower area and plumbing fixtures. The corrosion leads to the release of copper ions and the deposit of corrosion byproducts on the pipe wall. The solubility of these byproducts ultimately determines the level of copper at our taps. The only way to accurately determine the level of copper in water is to have the water analyzed by a laboratory. Examining localized pinhole leaks or “pitting” corrosion in high-pH and low-alkalinity waters also will help reduce the occurrence of copper pitting and the problems it causes

Sample Collection Procedure: At least two samples are required if the in-house plumbing is suspected to contaminate the water. One sample is collected at a point outside the house where the water is just introduced into the house or from the top of the water well, whichever is possible. The second sample is collected from the water faucet inside the house where most visible markers like blue stains are observed. For evaluating the household's highest level of copper exposure, collect a sample after water has been motionless in the plumbing system for at least six hours. Water drawn after an extended period of nonuse will show the highest level of copper. Collect the first water from the faucet without allowing any water to run before collecting the sample. First flush in the morning is hence the most appropriate sample. If it is not possible to collect the sample from the water line before entering the house as mentioned above, a substitute, flushed sample can also be collected by letting the tap run for at least 5 minutes after the first-flush sample has been collected.

Always use clean containers for sample collection. Collect at least a 500mL (half a liter) representative sample. One liter of sample is suggested from the in-house faucet to ensure a good representative sample (1 liter will collect water from approximately 6 feet of one-inch-diameter pipe; one gallon covers approximately 24 feet).

Interpreting the Results: Higher concentrations of copper in the first-flush sample than in the sample collected outside the house or in the flushed sample show that the copper is suspected to come from the plumbing material inside the house. Equal concentrations of copper in both the samples would indicate a source outside the house.

Removal of Copper from Water: Reduction in copper concentration on an individual-household basis may include:

Flush the water system before using the water for drinking or cooking. Flush each faucet individually for drinking or cooking purposes. Not required for non-consumption purposes.

Avoid cooking with or consuming water from hot water taps as hot water dissolves copper more readily than cold.

Use of alternative drinking water source such as bottled water or water treatment.

To reduce or eliminate corrosion problems due to acidic water of low pH, a neutralizing filter may be used.

Consult a qualified electrician if the problem is because of the electrolytic dissolution of copper or due to the grounding of electrical equipment to water pipes.

Reverse osmosis and distillation treatment can also be used to remove copper from drinking water.

How Can We Help You: The LSU AgCenter’s W.A. Callegari Environmental Center is equipped with analytical instruments and dedicated professionals to serve you in analyzing water samples for copper contamination. We are committed to furnish results on your samples within a minimum timeframe. For questions please call at (225) 765-5155. Submit your sample(s) in person or though overnight delivery to:

1300 Dean Lee Drive
Baton Rouge, LA 70820

Phone: (225)765-5155

Fax: (225)765-5158

Laboratory Manager: Javed Iqbal, E-mail

URL: Click here

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