Slogans advocating water conservation appear on all kinds of media. However, it is often not clear if and how much these campaigns can boost water-conserving behaviors, especially in developing countries. The current study tries to address this issue with a field randomized control trial (RCT) experiment in China. According to the longitudinal water consumption data, we found that 1) residents who received water conserving tips significantly reduced the subsequent water consumption relative to the residents who did not receive; 2) adding (vs. not adding) quantitative information into tips made the residents reduce water consumption; 3) adding (vs. not adding) norm information into tips failed to make the residents reduce water consumption. To our knowledge, this is the first study that quantitatively investigates the effect of water conservation campaigns on actual water consumption in developing countries. Our findings thus offer valuable insights on water efficiency information campaigns and policy-making.