Although the cisterns underneath Žlutý kopec (Yellow Hill) are a unique and well-preserved architectural monument possessing a certain aesthetic quality, they originally served a primarily technical, utilitarian function as part of a modern urban water supply network. The urbanization associated with the city’s massive expansion presented engineers and builders with great challenges, as it was necessary to build technical facilities that would meet the needs of the industrial metropolis’s growing population. In this respect, the city’s lack of a permanent supply of drinking water became a pressing problem in the mid-19th century, and so in 1863 a competition was announced for the design of a new water supply system. Of the four submitted plans, the project by London architect Thomas Docwry was selected sometime around 1869, and that autumn work began on the construction of a water treatment plant in Pisárky. Completed in 1872, the plant used three open biological filters with a total area of 2,940 m2 to purify water taken from the Svratka River upstream of the weir at Kamenný mlýn. A network of pipelines and water storage reservoirs was built at the same time. The purified water was pumped from Pisárky to reservoirs under Žlutý kopec (lower pressure level) and Špilberk (higher pressure level). To this end, some 1,800 metres of pipes were laid between 1870 and 1874 alone.
The cisterns on Žlutý kopec played an important role in Docwry’s plans for the city’s water supply network, as they constituted a large reservoir of clean drinking water for subsequent distribution. Construction of the first of three cisterns was begun in 1869 and completed in 1876. The fair-faced brickwork structure was expanded in 1896–1900 with the construction of a second similar-sized reservoir. Shortly after 1910, a third, double-chambered cistern was built in their close vicinity using modern construction techniques – for instance, it was made of concrete. The Neo-Romantic technical building that forms a part of the waterworks complex on Žlutý kopec also dates to the 1870s.
The earliest cistern, built in 1868–1876, measures 45 × 45 metres in area, is around six metres in height and could hold as much as 8,688 m3 of water. The central space consists of nine barrel-vaulted bays separated by parallel brick arcades. At its northern end, a separate drainage channel runs perpendicular to these bays. The entrance on the north-eastern side of the structure is a simple right-angled opening with a hatch set into a vault in one of the bays. On the cistern’s northern exterior is a rectangular valve chamber made of fair-faced brick on a concrete base. An inscription on the Dutch gable atop the small structure indicates its date of construction: 1913.
The second cistern, built in the late 1890s, has a volume of 8,611 m3, covers an area of 45 × 70 metres and is around eight metres high. It was also constructed of fair-faced brick and is similar in design to the first. It, too, consists of several bays with barrel-vaulted ceilings, separated by rows of arcades. One difference, however, is the use of a flat concrete floor. The newest of the three cisterns, built in the first decade of the 20th century, takes the form of two adjacent reinforced-concrete reservoirs connected by a large valve chamber. The two reservoirs measure 35 × 30 metres and 45 × 30 metres and are five metres high. The flat floor is divided by drainage channels, and large square concrete pillars rise from the floor to support a system of cross vaults. In the upper part of the reservoir, galleries paved with ornamental ceramic tiles provide access to the valve chamber. This upper area is rendered in white plaster, thus creating an interesting contrast with the grey concrete mass of the rest of the reservoir.
The ensemble of monumental underground cisterns, historically associated with the early days of building a modern water supply network for the expanding industrial city of Brno, is a unique architectural monument with distinctive architectural and technical characteristics. The well-preserved condition of this waterworks complex, which was not fully decommissioned until 1997, has made possible its recent opening to the public.
Šárka Bahounková