Sucralose is an artificial sweetener and an indicator of wastewater impacts in drinking water. N-nitrosodimethyamine (NDMA) is a disinfection by-product with wastewater-derived precursors. In two studies conducted in the United States and Canada, data showed watershed and region-specific relationships between sucralose occurrence, stream flow, and NDMA formation potential (FP). In addition, other water supplies have been identified with high NDMA FP that were low in sucralose, which appeared to be impacted by other sources of precursors in the watershed during high-flow events (e.g., runoff). In these studies, seasonal and climatic effects were explored where changes in stream flow (e.g., storm events, droughts) and sucralose and NDMA FP have been well correlated in many watersheds. These studies demonstrate the usefulness of measuring sucralose, including the determination of site-specific correlations with NDMA FP and temporal variability, as well as determining the likely percentage of treated wastewater in the influent of drinking water treatment plants.