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Copper tubing is commonly used in drinking water systems. Blue water corrosion is caused by general corrosion of the copper that produces blue-green discoloration. This article describes research undertaken to investigate microbiological effects on blue water corrosion. The results showed rod-shaped bacteria and exopolysaccharides and blue-green corrosion products on the tube surfaces. Field tests of a proposed biocidal treatment are underway.
Copper has been commonly used in drinking water systems for many years. In most applications it provides trouble-free service but is occasionally subject to corrosion. The corrosion of copper tubes used in water distribution systems is primarily responsible for the presence of copper in domestic water supplies. "Blue water corrosion" is caused by the general corrosion of copper, with the movement of primarily insoluble corrosion products from pipe surfaces into water.1 This process causes a blue-green cloudy coloration and is commonly known as "blue water" or "blue green water" (BGW). Blue water is most often noticed in soft waters after a stagnation period of several hours or days, and is typically associated with copper concentrations of 2 to 20 mg/L.1
Copper in drinking water has risks for public health. Copper has been reported to induce nausea, vomiting, diarrhea, and stomach cramps after acute exposure to concentrations >3 mg/L.2 The World Health Organisation guideline for exposure to copper in drinking water is 2 mg/L.3 It is also an aesthetic problem and can often be detected as a metallic, bitter taste in drinking water.4 The most obvious indications of contamination include a cloudy blue-green coloration and blue staining on sinks and tubs from the deposition of soluble copper as a soap scum. Showering in waters containing high copper concentrations can also cause a green tint to blonde hair.
The corrosion of copper is normally attributed to the chemical composition of water.1,5 Blue water generally occurs as a random phenomenon, however, and only certain areas of distribution systems are affected. Occurrences may be as extreme as one house on a street experiencing corrosion problems despite all houses receiving the same water supply. The sporadic nature of blue water corrosion has provoked intense research into its origins. Microbial involvement is one proposed cause.6
The authors have undertaken research into various aspects of copper corrosion for more than...