“Water, water everywhere, Nor any drop to drink.” So wrote Samuel Taylor Coleridge in his poem, The Rime of the Ancient Mariner, about seawater being unsuitable for drinking. In urban spaces too, this is fast becoming true. Extreme weather and urban flooding is increasingly common, yet pollutants and demand from greedy industries like food production leave populations thirsty. We seem content to do evermore damage to natural waterways and interrupt the water cycle with human activity, despite the inconveniences it causes us as a result. If anything, for too long water has been seen not as the resource it is, but as an inconvenience: hidden, fouled, and wasted. Thankfully, cities are beginning to wake up to the fact that impermeable artificial surfaces like concrete and asphalt are not conducive to flood management, and as urban sprawl radiates ever outwards, decision-makers are looking to blue-green infrastructure to mitigate the impacts of climate change. Aside from beautifying urban spaces, clever use of water is successfully integrating biodiversity back into cities, and it is being harnessed as a foundation for leisure activities and heat control. Our articles showcase some of the most revolutionary practices happening today, working at the interface where the urban and natural worlds intersect.