Discover the water reservoir under the Gellért Hill!

The water reservoir in an absolutely spectacular location is worth a visit. It does not only give you an exclusive and unique experience, but such water reservoirs in Budapest are very few in number, so take this opportunity to get in.

This year again you will be able to visit the József Gruber Reservoir on Gellért Hill, named after the engineer who had designed this two-basin structure. In honour of this year’s World Water Day, the reservoir will be open to the public between 21 and 24 March. Visitors can see that each basin is capable of storing 40,000 cubic metres of water and figure out how many planes could theoretically fit in (Mr. Gruber was a professor of Aerodynamics) – read QR codes for legends with English-language content at the exhibition in the foyer about how the reservoir works. (To compensate for the fact that we are offering Hungarian-language guided tours for the time being.)

This reservoir is a sight to behold and you would not expect such wonders under the hill. Amateur lovers of urbanism, with any national background, will have much fun. Water reservoirs are needed despite the fact that water is produced steadily from the 700 shore-filtered tap wells along the coasts of Szentendre Island and Csepel Island. Since the only way to operate the facilities economically is to have them run without a break, but consumption varies according to times of the day and to seasons, excess water needs to be stored either in reservoir pools or in water towers – they can also provide the necessary water pressure and fire water.

Gruber József Reservoir on Gellért Hill is the largest reservoir in Budapest. It lies under the area surrounded by the streets Hegyalja, Sánc and Orom. Each basin has a surface area of 5,000 m2, a capacity of 40,000 cubic metres, and a slab structure supported by 106 spectacular pillars. The pools are piano-shaped because these shapes allow water to circulate continuously, and so maintain water quality for as long as possible, and thus avoid stagnant water conditions which could harbour and grow waterborne bacteria.

The way of construction might be even more interesting. The construction took place between 1974 and 1980. 140 000 cubic metres of earth were being moved during the excavation work. The construction itself was all sheer excitement. The floor slab covers an area of 6,000 m2 (about the size of a football pitch) and is 30 cm thick – this needed to be built of concrete in one go to avoid any gaps or joints. To achieve this, twenty-five mixer trucks delivered concrete every hour on the hour for 41 hours non-stop with police backup at road junctions so that the concrete supply arrives on time, without a break. More than 200 people were involved in concreting and compacting around 50 m3 of concrete per hour (around 2,000 m3 in total). When a section of the base slab was finished, it was flooded with water after three to four hours.

This facility is unique both in terms of architecture and city operation. To visit, you will need to follow Fővárosi Vízművek (Budapest Waterworks) on Facebook and register once the registration is open (coming soon). A limited number of people are accepted to each tour, so do not hesitate to register without delay.