Introduction. In building sites, water is used for different purposes such as cleaning the used tools, meeting personal needs, making mortar etc. In cases of the building sites are far from the city center and/or water interruption is frequently experienced, water tank is used in the building sites to provide water. Aim of the study. To define the properties of the water tank used in the building sites in Turkey and to evaluate water tank usage characteristics of the users. Material and methods. We prepared 23-question survey and performed a survey study via internet with the civil engineers who are members of the internet-based forum site of the graduated from Department of Civil Engineering at Karadeniz Technical University and are still working as managers in building sites. Results. Water in the tanks used in building sites is generally city water. Water in the tank is mostly used daily for personal needs, cleaning and fabrication. Most of the existing water tanks are made of polyethylene. Water tanks were cleaned most recently by an average of 5.4±4.5 month (min.: 1 month- max.: 1 year) and cleaning is usually done with the facilities available in the building sites. Conclusions. Our findings indicate that water tanks used in building sites are uncontrolled, and there is not any legislation for the control and inspection of the water tanks.   Key words: water tank, building construction, construction site, clean water