The wastewater treatment plant is an extremely important infrastructure to ensure the quality of life, water use of human life, and other ways to ensure water quality for the natural environment. In the operation of it, there are always potential hazards affecting the health of the workers working in the factory. The study was performed using the Semi-quantitative risk assessment method to calculate the values of operational risks in the water treatment plant (WWP). The results of the study obtained 18 high potential hazards that may lead to the present in the water treatment process. The hazards were the leakage of deodorizing towers and the generation of toxic emissions of dead microorganisms that have the highest value with a risk scale of 20 points- frequent impacts on employees. The study has also identified the dangers present in WWP and this will be the premise for mitigating solutions for problems occurring at its.