Founded in 808 by Muhammad Mulay Idriss II, the first Muslim city in Morocco, Fez is one of the most sacred cities of Islam, the seat of the university that is older than the Sorbonne. According to Ibn Abi Zar in the twelfth century in the old town of Fez were built 785 mosques, more than 99 thousand houses, 93 town baths. As ville imperiale Fez was a major religious and cultural center but the greatest wealth of this city was water and the residents of Fez made perfect use of the opportunities offered to them by the strategic position in the region abundant in water. By the end of the twelfth century the hydraulic network of Fez provided running water to most of the buildings and as the source was used groundwater whereas water for domestic purposes came from river water. The network of river waters was canalized and in 1207 was built the first aqueduct which transported water for Adwat Al Andalus, the district inhabited by the descendants of settlers from Andalusia. Special lifting structures allowed for irrigation of fields and they still can be seen in Jnan Sbil. The original system was also used for the discharge of waste water: they were guided to a separate network f cannels, which sunk the sewage into the rivers flowing through the valley bottom. Water, so precious to the culture of Islam symbol of vitality but also a sanctified item of religious rite could not be collected anyway and anywhere. The hydraulic system of Fez supported more than 70 public fountains and about 4,000 private shots. Particular concern which water was given did not allow residents of Fez to waste it, as after use the water of the fountains was not treated as dirty enough to get into the sewage system. It was driven into special garden ducts or used for household purposes. The factor, which further reinforced the strong link between urban tissue of the town and the hydraulic system, was use of water in the craft, such as mills, tanneries or dying of materials. Flourishing in the Middle Ages Fez el-Bali by the end of the twentieth century rather reminded slum district with dirt, piles of rubbish, floating from everywhere unpleasant odor. The scale of deterioration of urban environment is even greater taking into account the unique historical value of almost perfectly preserved over a thousand-year-old system of urban tissue surrounded by city walls and buildings going back to medieval times. During the pre-industrial period sewage which sunk to the Oued Boukhrareb river was readily biodegraded. The introduction of “modern” manufacturing systems such as brass products resulted in a significant increase in the concentration of heavy metals in the rivers. The report from 1999 suggests that approximately 100 kilometers off the city the riverbed is practically dead. Change in the chemical composition of the waste water caused that the amount of harmful substances exceeded the self-cleaning capabilities. Most probably by 2020 the level of pollutants will have doubled. Contact with contaminated water in this region is responsible for more than 50% of all diseases, including epidemics of cholera, typhoid and diarrhea fatal. The first proposals for the rehabilitation of the old town area occurred already in the 70s of the twentieth century with the interest of UNESCO researchers and a group of local activists led by Titus Burckhardt. After entering the area on the UNESCO list of Heritage of Mankind in 1981, were conducted further detailed on-site testing and analyses and the published reports are now the core of contemporary efforts to adjustments on the concept of sustainable development. For almost 20 years the program of revitalization of Fez has managed to achieve much, much also remains to be done. The process is focused on two main issues: housing and infrastructure. The key aspect of maintenance activities was thus re-discovery of traditional methods of manufacturing building materials and principles of construction and decoration of architecture which were abandoned and forgotten with the emergence of modern construction techniques. As the program is complex it includes renovation of former buildings, revitalization of hydraulic system, education of the population and providing jobs for them, possibility to purchase homes by foreigners, better access to wheeled transport and last but not least improving the quality of waters. What distinguishes the program of revitalization of Fez is also integration of activities at the level of planning. Maintenance in this case is not only keeping the facility affected by degradation, it goes beyond the pure delight at the historic icon. It is part of the process of protection of live and active urban tissue, a further factor in stimulating economic and social development and finally a way to save 1200-year tradition.