We describe a Smart City, self-powered, water monitoring solution that uses low-cost water turbines. These can generate up to ∼ 4 W electrical power whilst reporting flow rates at UK domestic water pressure levels. This permits the novel use of stand-alone, remote Apache Spark Streaming as a distributed alternative to the conventional hierarchical Smart Grid. A future Smart City will have innovative features such as high-frequency monitoring of water flows, automated leak detection and shutdown with no requirement for utility electrical power.