The cost of desalinating seawater varies widely from country to country, depending on costs of production, mainly energy and capital. The cost of energy (gas) in a gas-surplus country is simply that of gathering and delivery to the desalination facilities. The cost of capital is similarly variable; it is lowest in a capital surplus country and highest in a capital-short country. Optimal choices of desalination technologies are another factor that determines the economics of desalination. This paper will provide an overview of the economics of desalination with an emphasis on the Saudi experience.