The paper describes the main sources of water contamination and sewage sampling. Describes the quantity and composition of wastewater as well as the water quality of the receiver where waste water is discharged. More details are given about these parameters, as well as possible causes of wastewater pollution. The division into pointy and scattered sources of pollution is explained. The main sources of pollution of rainwater from road roads are described and the main factors of their transfer to ground and water are described. These pollutants by nature are scattered and difficult to evaluate within the limits of accuracy characteristic of spot contamination, and due to adverse impacts on soil and water, it is important to determine them so that the necessary protection measures can be taken. In the oil refining process, waste water is generated that contains pollutants and pollution and can reduce the quality of the coastal sea and endanger the communities in it. Therefore, waste water is cleaned prior to discharge or re-use. The paper deals with oil refinery wastewater treatment technologies. The day is an overview of their content and a comparison with the prescribed maximum permissible concentrations. Water sampling processes, storage and delivery of samples to the lab are described, as well as analyzes of the same, all to ensure the quality of water. Wastewater samples are provided for analysis by licensed water testing laboratories. Laboratory analyzes samples according to certain norms and rules. Microbiological tests and laboratory analysis of wastewaters have been carried out.