
Authorities in Vienna are constructing what will become the world’s largest enclosed drinking water reservoir, with a capacity of around one billion litres.
The reservoir is being built as part of an expansion to an existing facility in Neusiedl am Steinfeld, a village in Lower Austria’s Neunkirchen district. The site already houses a water storage system, originally built in the 1950s.
The project forms part of the city’s Vienna Water 2050 strategy, aimed at securing future water supplies. Speaking at the construction site, Vienna’s mayor, Michael Ludwig, said: “Ensuring a reliable water supply for the people of Vienna is my top priority.”
At present, the facility consists of four vast water chambers, capable of storing 600 million litres. The reservoir is built into the natural gradient of the First High Spring Water Main, allowing water to flow towards Vienna without the need for pumps.
The expansion will be carried out in two phases. By the end of 2028, two additional chambers will be constructed, increasing capacity by 200 million litres. After four years of work, total storage will reach 800 million litres. A further expansion, planned from 2029, will add another two chambers.
Once completed, the reservoir will hold one billion litres of water – enough to fill a football pitch to a height of 140 metres.