In this study, water systems in the city of Istanbul, which carries a city museum character among the cities of the world in terms of culture, scope, technique and usage characteristics have been discussed. The preservation problems seen in Kırkçeşme Water System and in the water buildings of this system have been mentioned. It has been neglected that the waterways associated with water, vital to life, must be preserved as cultural assets. These values are not preserved as a result of planning lacks, wrong policies, rapid development efforts and changes and distortions caused by unconsciousness. This article gives brief information on historical water systems and focuses on the introduction of Kırkçeşme Water System and the changes and deterioration in this system.