A field experiment was conducted at Water Technology Centre, College of Agriculture, Rajendranagar, Hyderabad during rabi season 2009-10 to study effect of varying drip fertigation (Nitrogen and Potash (K2O) kg ha-1) levels on water productivity of bush bean (Lablab purpurium var. Typical L.) through drip irrigation. The main plot treatments consisted of four irrigation levels viz., Surface irrigation at IW/CPE ratio 1.0, Drip irrigation at 100% Epan, Drip irrigation at 80% Epan and Drip irrigation at 60% Epan and three fertigation levels in sub treatments viz., No N & K application, 50 kg N and 50 kg K2O ha-1 and 100 kg N and 100 kg K2O ha-1. The results revealed that yield attributing characters included number of pods per plant and pod weight were maximum in all the three pickings when irrigation was scheduled at 100% Epan with application of 100 kg N and 100 kg K2O ha-1 . Similarly significantly higher green pod yield (3556 kg ha-1) was realized by scheduling irrigation at 100 % Epan which was 9.5% and 22% higher than the irrigation scheduling at 80% and 60% Epan, respectively. However, drip irrigation scheduling at 60% Epan recorded significantly higher water productivity (0.72 kg m-3) over drip irrigation at 100 %, 80 % Epan and surface irrigation at IW/CPE = 1.0. Irrespective of the irrigation levels, gradual increment in fertigation level from no fertilizer application to100 kg ha-1 N and K2O increased water productivity (0.61 kg m-3) and yield. The increase in the yield was to the extent of 4 and 21 % more than application of 50 kg N + 50 kg K2O ha-1 and no fertilizer application, respectively.