This study focuses on evaluating the validity of surface water and well water for the purpose of using it in the preparation of drilling fluid with bentonite clays of fatha formation taken from four sites for three Iraqi governorates are (Salah al-Din, Kirkuk and Ninevah), the selected sites from which water was Collected from (Upper Zab water, Lower Zab water, Tigris River water and well water), to conduct chemical and physical tests of water samples and indicate their suitability in using them as drilling fluid, and this analysis included properties Physical and chemical, which is the (pH) Total dissolved solid (TDS) and electrical conductivity (EC) and the Concentrations of Cations (Ca+, Na+, K+ and Mg+), and Anions (Cl-, HCO3-, SO4- and CO3-), and the results showed the suitability of water as a drilling fluid and rheological properties were tested (Rheological) for samples (density, viscosity, pH, Filtration and calcium ions). As well as adding some activated chemicals such as (XC-polymer, CMC L.V, Caustic Soda) to the drilling fluid and gave appropriate results according to the American Petroleum Institute (API).