The quality of drinking water that is essential for life is a powerful environmental determinant of health. Engineering works in all fields have been constructed to distribute water from places of abundance to places in need. All water sources contain suspended and particulate inorganic/organic substances that must be dispelled during water treatment process to yield pure water that is fit for drinking and any other usage. Treatment procedures should be chosen in order to improve water stability. Many treatment processes (sometimes called unit processes and unit operations) are linked together to form a treatment plant in order to produce water of the desired quality. Unit operations, which are physical and chemical (aeration, adsorption, membrane processes, ion exchange, coagulation and flocculation, chemical oxidation and water softening) and mechanical (sedimentation and filtration) should be taken into consideration for producing clean drinking water. Choosing the suitable treatment process is a critical step in the procurement of safe, reliable, high quality drinking water at a cost-effective price for green/sustainable engineering. As a main part of the EU Project titled as “Implementation of ECVET for Qualification Design in Drinking Water Treatment Plants and Sanitation for Pure Drinkable Water-PUREH2O” that includes environmental planning, training in the field of drinking water, sustainable development, sound practices not only in the field of drinking water but also affiliated treatment facilities, this study focuses on selection of the water source, unit operations for drinking water and choosing water treatment processes