Refineries are among the major consumers of water that has both process and non-process origins. The average refinery requires 2.5 gallons of water for every gallon of crude oil processed. Depending on the type of crude oil, composition of condensate and treatment processes, the characteristics of refinery wastewater varies widely. The design and operation of modern refinery wastewater treatment plants are challenging and are driven by technology. This article will highlight the most common types of waste streams in a refinery and suitable wastewater treatment strategies.