“Magnifique!” I overheard someone say when they saw the siphon de l’acqueduc Napoleon III for the first time. The Aqueduc de la Dhuis, including this siphon, dates back to Napoleon III. It runs far beyond Seine-Saint-Denis and Seine-et-Marne. It stretches 131 km from Pargny-la-Dhuis in Aisne to the Ménilmontant reservoirs in Paris.
Engineer Belgrand designed this structure. He worked with Baron Haussmann under Napoleon III. They collaborated on a project to supply the capital with drinking water. Construction of the aqueduct occurred between 1863 and 1865. That year, it went into service.
The siphon de l’acqueduc Napoleon III is buried between 2.5 m and 4 m underground. Baron Haussmann described the water from it as wonderfully clear. This system now transports 22,000 m3 of water daily to Paris. Primarily, it supplies the Marne-la-Vallée theme park.
The Aqueduc de la Dhuis was the first system to improve Paris’s water supply. Eugène Belgrand built it at the behest of Georges-Eugène Haussmann. Napoleon III wanted to modernize the city. The water line begins in Pargny-la-Dhuys. Here, it collects water from the Dhuis River. It ends in the Ménilmontant reservoir in Paris. Today, it mainly serves Disneyland Paris 32 km east of Paris.
The Aqueduc de la Dhuis has a very slight incline. Over its 130 km length, the height difference is only 20 m. This equals a gradient of 1:6500. Yet, this slope is enough for gravity to power the water flow. The average flow rate is 22,000 m³/day. The line crosses 21 valleys using inverted siphons. Inspection access points exist roughly every 500 m. Kilometer markers line the route.
Originally, Eau de Paris operated the Aqueduc de la Dhuis. In 2015, the upper section from Pargny-la-Dhuys to Chessy was sold. The Val d’Europe Agglomération community association bought it. This association supplies water to Disneyland Paris. The aqueduct traverses four departments: Aisne, Seine-et-Marne, Seine-Saint-Denis, and Paris. Starting at 128 m altitude, it reaches 108 m in the capital. This gentle slope ensures water flows by gravity.
In places, the underground structure measures 2.20 m high and 1.80 m wide. Like most aqueducts, inspection shafts dot its path. Very few remain near Paris. However, you can spot “PH” markers. These hectometer markers indicate the distance from Pargny-la-Dhuys in hectometers. So the siphon de l’acqueduc Napoleon III stands as a testament to Parisian ingenuity. It highlights the city’s commitment to providing fresh water, even today.