Almost 95 percent of water on earth is saline and cannot be used as drinking water or for irrigation purposes. The desalination of seawater provides an opportunity to obtain additional drinking water or process water for people, industry and agriculture. In 2017, Siemens was commissioned by Rawafid Industrial and Advanced Water Technology (AWT) to set up a drinking water production plant on the coast of the Persian Gulf. The completed Al Khafji reverse osmosis desalination plant in North East Saudi Arabia is the world's largest solar-powered plant of its kind. Here, sea water is converted to fresh water through a two-stage reverse osmosis process powered by photovoltaic energy. Rawafid Industrial relied on solutions from Siemens for the electrical equipment, automation with integrated drive technology, communication and instrumentation. Through the efficient use of solar power, the plant reduces carbon dioxide emissions significantly compared with plants supplied with energy from non-renewable sources. In addition, the Siemens technology ensures system availability of about 98 percent. The vertical and horizontal integration of all electrical components reduces OPEX (Operational Expenditure) costs as well as maintenance times. Centralized process monitoring and automation ensure maximum energy efficiency and a sustainable water supply.