Decay in chloride content of ground water due to excessive

La Muralla well field near León, Guanajuato, Mexico, extracts water by means of 19 deep wells. 629 chloride analyses of the extracted water between 1994 and 1999, show a decreasing global trend of - 1.1 mg/L per year, estimated from linear regression. Should this demineralization continue, in a few years the water would reach the same composition of rain water. The findings suggest a severe reduction in the water reserve of the aquifer.