Water resources are becoming scarce due to climate change and anthropogenic activity, necessitating immediate action. The first step in conserving our water supplies is to manage them mindfully and sustainably. To achieve this, water sources must be monitored, mapped, and evaluated regularly. Updating national water maps using conventional methods can be a challenging task. Most of the obstacles have been addressed due to recent breakthroughs in the remote sensing field. In this study, we benefit from the remote sensing data integrated into Google Earth Engine (GEE) for developing an application for mapping Turkey's national inland water bodies. To achieve this, we explored the recently developed Multi-Band Water Index (MBWI) in GEE using Sentinel-2 satellite imagery and then applied it over the research area. The results showed that GEE is a promising application for dealing with large amounts of satellite data and can accurately extract water bodies on a national scale. The results might be helpful for various administrative applications that require up-to-date water information. The developed application can be used over different study areas and for spatiotemporal analysis.