Influence of tap water stagnation on copper and iron concentration as a function of pH

The water at the consumer's tap may have a quality far removed from that obtained from the distribution service due to contamination by metallic trace elements. This is why this work is interested in studying the influence of the stagnation of tap water on the concentration of copper and iron. Thus, the levels of Cu and Fe in water with a composition similar to that of the public water supply of Niamey (Niger) in stagnation in four types of pipe were monitored. These are cast iron, galvanized steel, polyvinyl chloride (PVC) and polypropylene (PPR) pipes. The analyzes of the water samples were carried out by flame atomic absorption spectrometry. It appears from this study that all the pipes made up of these pipes and accessories release Cu and Fe into the water under the conditions of the experiment. Metal pipes, in particular the cast iron pipe, release these two metals much more than plastic pipes, in particular PVC. Thus, the new cast iron pipe releases exceptional maximum quantities of iron of the order of 1 to 1800 times the guideline value of 0.3 mg.L-1 after 4 hours to 90 days of water stagnation.