The sanitary system is the most important supply system in a society. A central problem today is the provision of a future urban system which meets the requirements clearly borne out in environmental documents and action plans at local and global levels. The conventional water and wastewater systems have been questioned whether they can be considered as sustainable or not. Other small, decentralized systems have been implemented and a short description of different systems is shown. The attitudes, at different administrative levels in the society, to traditional and alternative sanitary systems are discussed. The general conclusion is that there is a strong driving force and an interest in changing the systems. However, the evaluation of the systems implemented so far shows that it is important to have time for careful and thorough investigations of new but also of existing systems in the light of the criteria for sustainability.