Feedwaters to a refinery are usually treated before being used in various processes. The type of treatment depends on the quality of the source water and its end use in the refinery. Turbidity, sediment, and hardness are examples of source water characteristics that may require treatment.

Water transmission systems include the channels necessary to transport water from one point to another. In most cases, it is necessary to transport water from its source to a treatment facility and from there to consumers. Pumping is used to provide the energy necessary to move the water from the beginning to the end of the transmission system. Pumping stations are usually located at the raw water intake, treatment plant and distribution network.

Because each water source is unique in terms of chemical composition, it is often necessary to conduct treatability studies to obtain design and operating parameters for treatment processes. Such studies are particularly important where a new treatment plant is proposed.

The main objective of a water treatment plant is to produce water that meets drinking water quality standards at a reasonable cost to the consumer. In a water treatment plant, various processes are used to produce water of desired quality. These processes are generally divided into two general categories: operational units and process units.