Research examined constructed wetlands (CWs) in piloting the ‘Sponge City’, a Chinese initiative designed, in part, to curtail extensive urban pluvial flooding. In Yangzhou a small number of exploratory qualitative interviews with relevant professionals elucidated key issues. The interviewees supported the concept of CWs but were uniformly sceptical about their viability. A possible CW in the city was also modelled, quantifying its effects and limitations. Results show that CWs can help attenuate urban flooding but there are important caveats concerning their implementation. These concern their size and capacity, sufficiency of urban space, and their economic sustainability. The political dimension of the Sponge City concept, including support from President Xi Jinping, suggests that CWs may be a distraction from more widespread urban flooding, which CWs may well not alleviate. Piloting is continuing and results will need to be more positive if Sponge Cities can be a strategically important flood attenuation measure.