**3. Why does digitization differ from earlier technology developments?**

Classical engineering-based research does not fully reflect the comprehensive developments of digitization. With digitization, something very big has happening with increasing speed. It has now also reached the water industry. An analysis of publications, studies and research carried out in the context of KOMMUNAL 4.0 in the field of industry 4.0 has shown that, in addition to technology patterns, other subject areas are important which will also have a serious impact on the water management. This applies, for example, to data sovereignty, data law and public procurement law.

Thanks to the accompanying research of the federal technology program "Smart Service World", in which the KOMMUNAL 4.0 project is embedded, and the associated networking with other Industry 4.0 research networks such as the federal technology program "Smart Data", the project partners in KOMMUNAL 4.0 are able to access the current state of knowledge and expected developments not only at the field of IT security and legal issues. These coming topics, some of which have not even been discussed in the water industry until today, are already the subject of KOMMUNAL 4.0.

Previous technology flows primarily arose from development ideas that were examined in individual objects or tasks. An example of this is the extended elimination of nitrogen in sewage treatment plants. When this aspect was investigated and applied broadly after being anchored in legislation, the effects were limited to the respective sewage treatment plant or the responsible organization. The other departments of a municipality, city or association were not affected. The same can be noticed for example for the so called fourth sewage treatment stage. From this point of view, research institutes and plant operators were able to investigate into such issues independently to get an isolated developed solution. Consequences of a lack of communication between research institutes were not significant due to low need of interdisciplinary interfaces. Although the existing scientific-technical exchange among experts is maintained and also inspires research initiatives, a mutual agreement on the research and development contents was not absolutely necessary for the previous form of technology development.

In opposite to aforementioned situation the appearance of digitization must be judged differently. Since as a cross-sectional technology it has an almost unlimited influence on all technological and organizational environments. At the horizontal level individual objects such as rain basins, flood reservoirs, water treatment plants or sewage treatment plants have to be connected more and more with the entire infrastructure systems across city and municipal boundaries. At the organizational level (vertical level) different departments and organizations have to be linked to each other. In addition, regional and supra-regional administrative and authority units should also be integrated into these networking efforts.

"It also applies to water management that everything that can be digitized has to be digitized". This comment made by Martin Weyand, BDEW Managing Director Water/Wastewater [7] confirms the cognitions of KOMMUNAL 4.0. Previous technological developments in water management have had only a limited impact on organizations and working methods, but in contrast to this, digitalization is expected to bring about massive changes in the everyday working lives of individuals as it unfolds its full potential. Already from individual elements as part of growing complex systems more far-reaching effects are to be expected. This leads to the conclusion that an examination of new digital solutions must be more comprehensive and must go beyond the previous horizon of knowledge and understanding. This is where the holistic approach of KOMMUNAL 4.0 comes in, in which all relevant individual modules and their interaction with each other were taken into account from the very beginning. This approach allows a better assessment of how to deal with digitization, even if it increases the amount of work at the beginning. As a result, it is easier to assess the major consequences of individual solutions and thus enables the foresighted engineering of networked systems. Based on this, current and future products and solutions will be manufactured.
