Traditional irrigation water management systems in China are increasingly replaced by user-based, participatory management through water users associations (WUAs) with the purpose to promote more efficient water use and higher farm incomes. Existing research shows that significant differences exist in the institutional setup of WUAs in China, and that WUAs have not been universally successful in saving water and improving farm incomes. This paper aims to examine the underlying causes of differences in WUA performance by analysing the impact of WUA characteristics on the efficiency of agricultural water use. Explanatory variables in our analysis are largely based on Agrawal’s user-based resource governance framework. Applying a random intercept regression model to data collected among 21 WUAs and 315 households in Minle county in northern China, we find that group characteristics, particularly group size and number of water users groups, and the existing pressure on available water resources are important factors in water use efficiency. We further find that WUA characteristics that positively affect water savings in crop production tend to increase the costs of inputs used in crop production, and thereby reduce or even fully offset the potential positive impact of water savings on farm incomes in our research area.