Field research was carried out in a sub humid climate at the Uludag University, Bursa, Turkey. Using the yield data obtained from the field research for 2011 and 2012, a partial economic analysis was conducted for watermelon (Citrullus vulgaris, var. Crimson Sweet) at four drip irrigation treatments of full irrigation [FI, 100% evapotranspiration (ETc)] and deficit irrigation (DI) [75% FI, 50% FI and 25% FI] and then compared to both physical and economic water use efficiency (WUE). Total costs and net incomes differed among irrigation strategies. Marketable yield (MY) and net income to land decreased with decreases in the amount of irrigation. The highest MY and net income to land were obtained with the full irrigation treatment. The results showed that full irrigation is recommended under non-water-limiting environments for higher yield and net income. The highest net income to water, physical WUE and economic WUE values were resulted from the 75% FI. With consideration to net income and water use efficiency, deficit irrigation management strategy of 75% FI under water-limiting conditions can be preferable, because it achieved irrigation water savings of 25%, an increase of 9% in crop water use efficiency and an acceptable net income with a yield loss of only approximately 8% compared with full irrigation.