The requirements for commercial dishwashers differ fundamentally from those for domestic dishwashers. For commercial dishwashers, capacity and programme duration are the main factors. Accordingly, different designs are offered for the different types of requirement. Comprehensive data on the usage behaviour of commercial dishwashers is scarcely available. Within the framework of face-to-face interviews, 200 companies in Germany and Denmark were visited to record their user behaviour. With the help of the data obtained, not only errors in the usage behaviour were found, but also indications of unnecessarily high water and energy consumption, which, inter alia, lead to increased costs for the companies. The results show that manual pre-rinsing in particular leads to increased water consumption. Furthermore, the dishwashers are only partially loaded, which leads to more wash cycles than necessary. In order to ensure the optimal utilisation and correct user behaviour of commercial dishwashers, while simultaneously reducing the impact on the environment, there is an urgent need to educate users better on how to use them correctly.