The principal sources of water pollution in the petroleum industry are produced water, drilling fluids and cuttings, process and drainage water, sewage, spills and leaks, and cooling water. Drilling fluids and cuttings can affect benthic organisms if discharged into oceans, while their high pH and salt levels pose risks to freshwater. Produced water is one of the largest waste streams and contains inorganic and organic compounds; its disposal requires evaluation and treatment. Proper treatment and disposal of drilling fluids, cuttings, and other wastes are needed to minimize environmental impacts.