Study was conducted at Coastal Agricultural Research Station of PARC, Saleh Muhammad Goth, Landhi, Karachi. In order to see the effects of marginal quality ground water in comparison to good quality water (tap water) on crop yield and water use efficiency. Okra was grown under drip system of irrigation during the year, 2011. The soil characteristics, soil samples at depth of 0-15, 15-30 and 30-60 cm were drawn and analyzed in laboratory for various parameters. The soil under study was sandy loam in texture, having the DBD 1.59 gm/cm3 , infiltration rate 1.56 cm/hr, F.C, W.P and A.M was 14.8%,6.2%and 8.6% respectively. Before crop sowing, drip irrigation system is installed, also assessed for its performance through Uniformity Co-efficient which ranged from 93 to 96% and indicating that the system was working satisfactorily. The quantity of tap and ground water applied through drip system to okra crop was of equal volume i.e., 6989.7m3/ha. However, higher crop yield and higher water use efficiency i.e., 18.93 t/ha and 2.7kg/m3 were recorded under T1 over T2 (yield 17.0t/ha and water use efficiency 2.4kg/m3) respectively.