Supplying the population of a refugee or internally displaced persons (IDP) camp with sufficient drinking water is a key concern of humanitarian organisations. This requires information on the geological and hydrogeological situation at the camp site, which is often missing or not available within a reasonable timeframe. Depending on outcrop situation and geological complexity, remote sensing can contribute to a rapid hydrogeological assessment, and greatly reduce the required fieldwork. In the context of the project EO4HumEn (Earth Observation based services to support humanitarian operations: monitoring population and natural resources in refugee/IDP camps, funded by the Austrian Research Promotion Agency FFG, ASAP 9, Nr. 840081), a team of hydrogeologists and GIS experts supported by Médecins Sans Frontières (MSF) Austria developed a workflow to extract hydrogeological information from easily accessible remote sensing data in a series of short-term desk studies. This paper provides a condensed, structured protocol on how to produce hydrogeological reconnaissance maps for humanitarian purposes using remote sensing data and GIS. In simple geological settings, these maps can be sufficient to plan and conduct drillings. In more complex situations, fieldwork remains indispensable, but can be guided towards the most suitable locations.