 Stable isotope signatures can be used to characterize subsurface water dynamics and provide valuable information about the movement of water through the environment. However, traditional sampling methods are time-consuming and expensive, making it difficult to collect data over long periods of time. In this study, researchers developed a cost-effective and efficient method for continuous in-city monitoring of poor water stable isotope signatures. They used automated valves to extract diluted water vapor from soil air, which was then analyzed by a commercial laser-based isotope analyzer. The results showed that the new technique provided accurate and precise data on the movement of water in the environment, allowing researchers to gain a better understanding of dynamic and heterogeneous shallow subsurface and vado zone processes. This article was authored by T. H. M. Volkman and M. Weiler.