Water contaminated or changed their properties partially or completely as a result of household, industrial, agricultural and other uses is called as waste water. The analysis used to determine the characteristics of the waste water are those of quantitative chemical instead of those of qualitative biological or physical. These are Biochemical Oxygen Demand test BOD5, Chemical Oxygen Demand test COD , Total Organic Carbon Content test TOC and Dissolved Oxygen DO . In this study, BOD curves were generated for the particular reaction conditions and the effects of reaction rate constant on these curves were studied firstly. Examining of the simulation curves related with BOD it is understood that the same conversion of BOD could be reached in a shorter time by increasing the reaction-rate constant. This is to be expected in terms of the reaction kinetics. Secondly, the correlations among the results of BOD, COD, TOC and DO tests in determining the quality of water resources were searched and it was seen that finding a correlation among these tests results would be impossible directly but some correlations could be done among the results of these tests applying for the same sample diluted in different rate. However, these correlations could not show on-line changes exactly among their relationships. Therefore, instead of BOD test to realize COD and TOC tests and to get their results in shorter time is easier and it may be advised that the rates of BOD5/COD or BOD5/TOC for the same sample at certain time intervals are determined nearby DO measurements so that it can be said something about the qualification of the water sources