A trial ten-year-old Valencia orange (Citrus sinensis Osbeck) trees budded on sour orange (Citrus aurantium L.) rootstock grown in this experimental research, was conducted over two seasons in 2021-2022, in the Nubaria area, EL-Beheira, Egypt, in sandy loamy soil. This experimental research was conducted to evaluate surface and sub-surface irrigation techniques on Valencia orange trees under different water stress conditions. In addition, the optimal irrigation technique was specified by comparing different irrigation techniques (surface and sub-surface) under different water provided conditions of estimated crop water requirements (ETc) (60-80-100% of ETc). The present research indicated that irrigation water for Valencia orange trees could be reduced by 20% without compromising their productivity. In addition, sub-surface irrigation techniques may allow increased production. As a result, sub-surface irrigation techniques below ETc-80% showed an improvement in water use efficiency (WUE), producing 4.04 and 3.96kg fruit per cubic meter of irrigation water in the first and second seasons, respectively. Our results showed that the use of sub-surface irrigation technique in combination with ETc-80% achieved a high economic return by increasing total production while raising WUE and water unit return (WUR) at the same time, which reached 16.15 and 15.86 Egyptian pounds per every cube meter of irrigation water in the first and second seasons, respectively, while 20% less water is consumed. Therefore, we recommend using the ETc-80%application in conjunction with the sub-surface irrigation technique for Valencia orange trees budded on sour orange rootstock so that we can obtain a high economic return while maintains rationalized irrigation water.