Article name: Lead levels in drinking water spike when copper and lead pipes are joined
http://news.wustl.edu/news/Pages/23098.aspx
In this article written by Diana Lutz talks about the harmful effects of lead if present in drinking water and how the replacement of the lead pipes to copper pipes can increase the lead content in water. Lead pipes when mixed with copper pipes, this leads to the increased concentration of lead contamination due to galvanic corrosion which is the process of corrosion wherein the zinc coating of the pipes is oxidised. According to the US environmental protection agency, the lead concentration in drinking water could be to a maximum of 15 parts per million. But the level has increased so far that this lead contamination is leading to lead poisoning among the human beings. The process of chlorination which is a halogenations reaction taking place in the presence of chlorine can be useful in removing lead from drinking water but chlorine again may end up forming free radicals (chlorine ions) in water which may be harmful if consumed. Lead has an oxidation state (Charge on an ion) of +2 and readily soluble in water. But, lead sulphate is more soluble in water than lead oxide and hence, more concentration of lead sulphate has been found in drinking water. With the increase use of chloramines that is chlorine related chemicals, the solubility of lead has found to be increasing in water. The pH of water is 7 but when lead and chlorine is added to water, the pH of water tend to increase up to 10. If a lead pipe transporting water is corroded, the phosphate content in the pipe if any can also lead to further corrosion increasing the dissolution rates of the lead corrosion.
Reference:
Hill, John., McCreary, Terry., & Kolb, Dorris. Chemistry for changing times (13th Ed.). Prentice Hall publishers.
