The ground water quality in Coimbatore city along the Noyyal river during pre-monsoon and post-monsoon seasons in 2005 is discussed in this paper. Water samples were collected from 12 wells on either side of the river. The physico-chemical analysis of the collected samples was carried out for the parameters, such as pH, total dissolved solids (TDS), electrical conductivity (EC), total hardness (TH), alkalinity, calcium (Ca2+), magnesium (Mg2+), chloride, sulphates (SO4(2-)) and sodium (Na+) . From the study, it is revealed that EC, Ca2+, Mg2+ have high concentrations in pre- and post-monsoon seasons. In most of the places, the quality of water was not found suitable for irrigational and industrial activities because of high concentrations of electrical conductivity and total hardness. In general, the values of all the studied parameters were high and above the standards during the post-monsoon season, compared to the pre-monsoon season in 2005.