The Water Safety Plan (WSP) is considered the preferred approach to ensure drinking water safety by the World Health Organization (WHO). This approach ideally requires extensive scientific and technical input from a multidisciplinary team of experts. However, in small- and medium-sized municipalities in Austria, financial and personnel resources are usually of very limited availability. Therefore, a spreadsheet based WSP tool was designed to facilitate the implementation of the WSP approach at these small supply units. The WSP tool comprises the relevant national Austrian guidelines, which include the key components of the WSP by the WHO. The tool provides an overview of the required steps, explains how to carry out each step and guides the user through the three key components: system and hazards assessment, control measures and operational monitoring, and management. The practical application of the WSP tool was tested at 12 water utilities over a period of three months. After this period, the tool was improved based on collected feedback from the water utilities.