The aim of this study is to reflect the current knowledge for conserving water resources through the use of modern and efficient irrigation system and moisture regime, and to study their influence on water productivity. Green snap beans (Phaseolus vulgaris, L.) as the largest vegetable in value terms exported from Egypt, was cultivated in the Faculty of Agriculture Experimental Farm - Cairo university - (30˚ 02` N latitude, 31˚ 12` E longitude) for two seasons; spring and autumn plantations. Crop yields of two seasons were measured under the use of different irrigation systems [drip, and furrow with gated pipe]. Also with using different irrigation regimes [SMD_0.10, SMD_0.25, SMD_0.40, and SMD_0.55 in which irrigation was applied at 10%, 25%, 40%, and 55% soil moisture depletion from soil available water, respectively]. Under field experiment, higher crop yields and the highest water productivity were obtained using drip irrigation system with SMD_0.10 compared to high yield obtained under furrow irrigation even if gated pipes were used for applying irrigation water. Model programs were used for estimating crop water requirements and irrigation scheduling to save time and efforts of the field work. "CropWat" program gave similar results as the actual ETa values. Unfortunately the program can't carry out actual daily irrigation scheduling before the month elapse as it needs average monthly reference evapotranspiration (ETo) data. "BUDGET" program gave lower similarity compared to the actual data, but it has the possibility to carry out actual daily irrigation scheduling as it is possible to take ETo data as daily value. As for "IRRI-CLAC" program, it gives the lowest similarity and has weak possibility and flexibility to be used to calculate irrigation scheduling.