Paris’s dual water network

Paris uses two separate water systems. One provides drinking water, while the other supplies non-potable water for cleaning and public use. This second network, built in the 19th century, is more than twice the length of the Seine.

Historical development of the system

The non-potable water network was established in the mid-19th century under the leadership of engineer Eugène Belgrand during the Haussmann urban renewal. It was designed to ensure a secure and separate supply for public cleanliness and beautification, distinct from the drinking water system.

Water sources and treatment

The network primarily draws water from the Ourcq canal, with additional water from the Seine and the Marne rivers. Water is treated minimally, using screening and sieving to remove debris, and then distributed at low pressure, mostly by gravity. It is stored in eight reservoirs with a combined capacity of around 152,000 cubic meters.

Uses of the non-potable water

The non-potable water is used for cleaning streets, gutters, and sewers, as well as watering green spaces and filling lakes in the Vincennes and Boulogne woods. The system has a maximum capacity of over 547,000 cubic meters per day, though the average usage is around 214,000 cubic meters daily.

Modernization and maintenance

The Paris Council has committed to maintaining and modernizing the network, with a 2022-2034 plan allocating nearly 36 million euros to reduce leakage and improve efficiency. The network extends beyond the city center, reaching the small ring and including the pipelines in the Boulogne and Vincennes woods.

Environmental and practical benefits

The non-potable water system helps preserve resources, reduce energy costs, and support biodiversity. It also contributes to cooling the city, aligning with efforts to combat climate change. However, it is important to note that this water is not suitable for drinking and should not be used for consumption.