The Oldenburgisch-Ostfriesischer Wasserverband (OOWV) is a public law corporation in northwest Lower Saxony, Germany, responsible for providing drinking water and wastewater treatment. It serves over a million people with drinking water and handles wastewater for over half a million citizens. The organization operates 15 waterworks and 46 wastewater treatment plants, making it one of Germany's largest water and wastewater service providers.