AbstractBy using the data of 30 provinces from 1998 to 2016 in China, this paper estimates the water rebound effect in the agricultural crop farming by combining Slacks‐based Measure (SBM‐based) of Malmquist Index and Logarithmic Mean Divisia Index (LMDI) method. We find that the average water rebound effect is 70.3%, implying that over two‐thirds of the water saving from irrigation technology improvement is offset by higher water consumption. We find evidence on the regional heterogeneity in terms of the magnitude of rebound: Southwest is the highest, whereas Northwest is the lowest. The heterogeneous rebound effect across regions is mainly due to the difference in water endowment and irrigation land availability. Our results indicate that irrigation technology improvement is not necessarily sufficient for achieving agricultural water conservation. In particular, the difference in natural geography conditions across regions needs to be considered in designing water conservation policies at a sub‐regional level.