The article focuses on both results of analysing the quality of the surface water taken from the reservoir and effectiveness of the water treatment process' technological examinations carried out both on a pilot station and in a technical scale. The research was carried out on the basis of the water taken from the reservoir named “Sosnowka” which is located at the Karkonosze mountain range bottom. There were 27 physical and chemical factors that underwent the examination.
The effectiveness of the water treatment process was assessed basing on such factors as follows colour reduction, turbidity and such indicators as: alkalinity, total hardness, oxidability and conductivity.
The 1st stage carried out throughout the water year included examining of the water treatment process' effectiveness in a pilot station in various technology systems by means of such unitary process as: sieving, pre-ozonation, pH correction, coagulation, filtration on anthracite and sand bed, final ozonation and sorption on active carbon.
The other stage concerned examination carried out in a technology system in a technical scale of a new water treatment plant. The good quality of the examined water at that time (pH = 6,9; colour = 15 mgPt/L-1) allowed for using a simple technology system with the use of such processes as: sieving, pre-ozonation, filtration on anthracite and sand bed, final ozonation and sorption on active carbon and final correction of the water quality with Na2CO3 and MgCl2.
The results aquired while carrying out laboratory technological examinations and those in technical scale allowed for establishing 3 optimal technology systems to be implemented while the water treatment plant operates.