The Swiss sanitary engineering is facing increasing uncertainty. New impurities, new regulations, new technologies, and changed supply and demand structures lead to the fact that prognosis based on a linear continuation of today’s condition are being questioned more and more. Long-term planning is getting difficult. In addition, more drastic changing processes have to prepared on a long run, since sanitary engineering can hardly be adapted to changed social demands, new technical developments or risks in the short term because of its complexity and the durability of the technical equipment.