Gelsenwasser AG engages in the water, energy, and service businesses in Germany, the Czech Republic, and Poland. It operates through Water, Wastewater, Energy Networks, Energy Procurement & Sales, and Investments and Projects segments. The company engages in the purchase, production, sale, and transport, and distribution of drinking water; investment in municipal utilities; planning, construction, and operation of wind turbines and photovoltaic systems, as well as charging infrastructure; and provision of digital solutions and services comprising radiator controls, digital meters and metering point operations, and neighborhood solutions. It is also involved in the operation of sewers, and sewage and wastewater treatment plants; installs mini combined heat and power units; district heating solutions; heating solutions; water supply, wastewater disposal, and groundwater management activities; rental of standpipes; fault repair services; purchase and sale of natural gas, electricity, and heat to household customers, special contract customers, and resellers; and energy procurement and trading business. The company was formerly known as Wasserwerk für das nördliche westfälische Kohlenrevier and changed its name to Gelsenwasser AG in 1973. The company was founded in 1887 and is headquartered in Gelsenkirchen, Germany. Gelsenwasser AG operates as a subsidiary of Wasser und Gas Westfalen GmbH.