At the intersection of Avenue de l'Observatoire and Quai du Parc, the water plant has long exploited the Marne to redistribute drinking water to the inhabitants of the city. Built in 1864 by the Eastern Railway Company, the plant was transferred to the city in 1890 but it was not until 1926 that the Municipal Water Service took over the entire operation of water autonomously. The factory was completely rebuilt in 1966. Capable of producing up to 48,000 m3 of drinking water, this water plant has always been at the forefront of innovation: water quality control by luminescent bacteria, truitometer, electrochloration. These innovative processes were put in place during the many upgrades. In 2016, the transfer of water treatment competence to the Paris Est Marne & Bois territory ended its activity. From now on, the City of Saint-Maur has committed to converting the factory into a space open to the public, a demonstration of the sustainable city.