Leaching of brasses in long-term direct contact with water

Abstract

Copper-zinc alloys (alfa-beta brasses) are currently used to produce house water piping and further parts, that might be in direct contact with drinking water. Lead is added to these alloys in order to improve their machinability. It is well known that lead is unhealthy for humans and, according to EU Council Directive 98/83/EC on the quality of water for human consumption, the admissible Pb content in drinking water has to decrease during the next years because of its high toxicity. The interest in improving public health evocated the need of developing new ecological materials for application on water piping and systems because extensive research indicates that the occurrence of increased Pb content in drinking water can be due to the release (leaching) of Pb from leaded copper alloys. As a consequence of such findings, the dissolution /erosion behaviour of a commercial sanitary brass tap, submitted to a dynamic test simulating the service conditions, has been studied. For that purpose an equipment that enables a long – term direct contact with water has been designed and developed. The chemical composition of the tap and of the final residue produced during the test have been determined by XRF spectrometry and the solutions analysed by atomic absorption spectrometry. Results concerning metal values dissolution have been compared with the limit values established by the legislation. For the experimental conditions, results show that Pb level in leaching solution is lower than the admissible value indicated for the quality of water for human consumption.