Physiochemical and hydrochemical study of the groundwater aquifers of Islamabad Sectorial and National Park areas were made. Water samples collected randomly from fifty-nine tube-wells/dug-wells were analysed chemically in the National Institute of Health, Islamabad (Pakistan). Chemical quality data thus obtained have been verified statistically for its reliability and conformity in terms of chemical identity among aquifers. This data is then projected graphically on the Trilinear Piper and Stiff Pattern diagrams by using USGS software "HC-GRAM". The Stiff Pattern diagrams thus developed for each well are projected on the map of Islamabad to visualize the distribution of groundwater chemistry. "WATEQ", USGS Water Equilibrium software, is used to evaluate the variety of chemical parameters to be used for further extending this study. Results indicate that most of the Islamabad aquifers are of excellent quality and fall in the category of HCO3-type, Ca-HCO3 type, Na-HCO3 type, and Na-type. Groundwater available at Dhok Mori, Dhok Chapran and in some sites of Sectors I-8 and I-9/4 are highly contaminated.