Finally, a custom-designed photoreactor (Fig. ) was used to demonstrate integrated water splitting and clean water production from the River Cam. In the reactor, H2 from water splitting was trapped in the gas-tight headspace of the reactor while condensed water vapour from the SVG formed droplets on the sloped window which flowed down into a separate partition for collection (Fig. , Supplementary Figs. 18, 19). Fig. shows that under AM 1.5G irradiation, the H2 evolution and clean water production rate of SVG-PC were 16.1±3.6 mmol m -2 h -1 (STH: 0.11±0.02) and 0.94±0.12 kg m -2 h -1 , respectively (Supplementary Table ). These values were similar to those obtained from separate H2 evolution and water evaporation experiments, thus confirming the successful demonstration of simultaneous water splitting and clean water production by SVG-PC. The slight drop in performance could be attributed to the scattering of light from the water layer and droplets formed on the tilted window of the integrated reactor.