The following conclusions have been made on the basis of interpretative results, statistical analogies, on-site geological information and geophysical well logging:
1. Overall conclusive interpretation indicates sodium and magnesium as the most dominant cations available in the groundwater of Islamabad. However, in some areas like Pandori, Dhok Saknal, H-8, H-9 and I-9 calcium is the dominant cation, and is also found dominantly in the several water samples of wells such as, NP-13 (Dhok Mori), TW-43 (G-9/2), TW-42 (G-9/4). TW-63 (G-8/4) and TW-73 (G-10/2).
2. Likewise, bicarbonate is the most dominant anion available in the groundwater of Islamabad, except in areas like Tarlai Kalan, F-10, I-8 and I-9/4 where dominant anions are sulphate and chlorides.
3. Groundwater available at Dhok Tarlai, Dhok Farash, Dhok Mori, Dhok Chapran, and in some sites of sectors I-8 and I-9 are of saline nature, and they exhibit high values of TDS (1189 - 5570 PPM) and E.C. (990 - 2230 micro-mhos/cm). Moreover, presence of nitrates and fecal coliform bacteria are also found.
4. The values of hardness appear to be much above the permissible limit from the analysis of fifty-nine groundwater samples. Such water would normally cause scale formation (carbonate mineral precipitation) if boiled in container.
5. Trilinear diagrams of sectors G-7, G-8, G-9, G-10, H-8, and H-9 show that groundwater is magnesium-bicarbonate type, which in turn reflects its source of recharge from the adjacent Margalla hills mainly composed of limestone. Trilinear diagrams of Sectors I-8, I-9/4 and F-10, Tarlai and Farash show that groundwater is sodium/sodium-sulphate type with minor amount of Ca+2, Mg+2, Cl- and HCO3-.
6. The existence of four types of aquifers is concluded on the basis of their ionic behaviour. These have been classified into HCO3 type, Ca-HCO3 type, Na-HCO3 type, and Na type categories.