In Nigeria, it is standard practice to discharge petrochemical compounds on sewage degradation in a septic tank, which has led to consistent sewage dislodgement in the septic tank that serves our household. The study was carried out to determine the effect of some petrochemical products, such as petrol, kerosene, and diesel. Some laboratory tests were conducted, which included biochemical oxygen demand (BOD), chemical oxygen demand (COD), pH, conductivity, and total coliform count. Under aerobic conditions, the researchers built four different experimental sewage treatment systems in the lab. We used a scale ratio of 2: 1 for the effluent and petrochemical products in order to get a total mixture of 200ml for both since the reagent bottle, we used for the test has a total measurement of 300ml. With respect to the above ratio, 33 mL of effluent and 67 mL of petrochemical products such as petrol, kerosene, and diesel were poured into each of the three samples (i.e., the 300 mL reagent bottle), and the last sample was used as the control. Samples were collected at a weekly interval for a period of four weeks for the laboratory tests. The findings of the tests revealed that there was a slow rise in the BOD and the COD during the second week, but that this rise eventually slowed down and became smaller over the course of time. Weekly, the pH, conductivity, and total coliform count decrease. The abrupt spike in the second for BOD and COD is due to the presence of additional carbon, hydrogen, and oxygen molecules, which eventually decrease with time. This merely indicates that petrochemical products have the potential to be utilised in the reduction of biological oxygen demand (BOD), chemical oxygen demand (COD), and coliform bacteria found in sewage.