 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 situ 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 beta-zone processes. This article was authored by Th. M. Volkman and M. Weiler.