A rapid expansion of urban systems, particularly in less-developed countries, pose considerable challenges. Urbanization also provides opportunities for socio-economic progress. Relative contribution from the urban sector to national economic growth is very high. The fate and the role of the socio-economic system in local, regional and national development hinges on many circumstances. Apart from delicate social issues, deficiencies in water provision, internal distribution and a hazardous water and environmental quality represent basic and tangible daily problems. Urban water security requires fresh thinking at two levels. Some kind of basin authority (corresponding to a county council, i.e. a formal administrative and regulatory body for the geographical area within a river basin) in combination with a national water policy is required, notably in countries that contemplate, or are in the process of implementing, regional and sometimes inter-basin schemes to augment supply to growing conglomerations. Similarly, the generation of large volumes of waste water and the associated threat to downstream areas cannot be effectively tackled through conventional urban planning. Within the urban area, and particularly in non-regulated parts, there is an urgent need for institutional arrangements that facilitate operations for providers who have the capacity and ability to function under the prevailing circumstances. Introduction of effective production and treatment technologies are other necessary and urgent prerequisites to reach urban water security in Third World cities.