Hidden beneath Parisian soil lies the Ancienne réserve d’eau a fascinating piece of history. This wasn’t just any water reservoir. It played a vital role in supplying the city with fresh drinking water. Before its creation Parisians relied on the Seine. The Seine’s water quality however declined. Industrial growth and seasonal temperature changes made it increasingly unsuitable for consumption.
The Ancienne réserve d’eau is a testament to the ingenuity of Eugène Belgrand. Belgrand an accomplished engineer general of Bridges and Highways was instrumental in the renovation of Paris under Napoleon III and Baron Haussmann. Between 1852 and 1870 he designed several reservoirs. He also masterminded the Paris sewer system and the aqueducts of Vanne and Dhuis. The Ancienne réserve d’eau was part of his ambitious plan to provide cleaner water for all Parisians.
Construction of the Ancienne réserve d’eau was no small feat. Built upon old quarries it required a massive underground reinforcement project. Nearly 1800 masonry pillars were constructed to support the immense weight of the reservoir and its vast water capacity. This impressive engineering feat was overseen by Octave Keller who would later become Inspector General of the Seine’s quarries. The reservoir’s clever design included a grassy covering maintaining cool and humid conditions. This kept the water at a constant temperature of 12 degrees Celsius.
The Ancienne réserve d’eau’s story extends beyond engineering. Initially named the Reservoir de la Vanne and later Reservoir de Montrouge it was once considered the world’s largest potable water reserve. It drew water from sources including Vanne Voulzie and Lunain. These sources often traveled over 150 kilometers through aqueducts reaching the reservoir by gravity alone. A truly remarkable achievement of its time.
The reservoir also housed innovative methods of water quality control. Inside a chamber featuring artificial rock walls were special aquariums known as truitomètres. These held trout incredibly sensitive to pollution. If the trout showed signs of weakness the water was deemed polluted and diverted to the sewers. While this method was later replaced by laboratory analysis the truitomètres stand as a testament to the dedication to quality water.
The Ancienne réserve d’eau remains a silent guardian of Paris’s water supply. While hidden from public view its history is rich and intricate a symbol of Paris’s evolution and commitment to providing its citizens with clean and safe water. It is a reminder of remarkable ingenuity in both engineering and public health. Its history shows how much effort and foresight went into building the modern Paris we know today.