The densely-populated mega-city of Shanghai relies increasingly on freshwater from the Changjiang estuary (70% now). However, this strategy is facing potential threats due to extensive water diversion in the lower Changjiang basin and future sea-level rise. Given this, the present study evaluates the ability of Shanghai to source its water from the estuary, especially in the dry season. Flow 0.45 for 20-65, 75-90 and 120-128 days (in 2020, 2030, and 2040, respectively), for extreme low-flow conditions. These periods exceed the present 68-day maximum freshwater storage in Qingcaosha reservoir, which is meant to secure freshwater for Shanghai in the future. Urgently countermeasures are needed to secure the Shanghai's water in the future. © 2014 Elsevier Ltd. All rights reserved.