Vienna is raising the bar on urban flood protection. Beneath the popular beaches and bike paths of Danube Island, a massive engineering upgrade is underway: the installation of Europe’s most powerful rainwater pump. Designed to handle extreme storms in seconds, this new system reflects Vienna’s commitment to resilience in an era of unpredictable weather.
Danube Island is one of Vienna’s favorite leisure spots – a green ribbon in the Danube with beaches, watersports, restaurants, and nature reserves. But behind the calm scenery lies another identity: a cornerstone of Vienna’s flood-control system. Built to stay at least a meter above water even during major floods, the island separates the Danube from its relief channel, the New Danube. At its center sits one of Europe’s largest pumping stations, ready to divert water when heavy rain threatens the city.
Extreme rainfall is no longer rare – it’s becoming a regular stress test for cities across Europe. Vienna knows this well. In recent decades, storms have grown more intense, and when the Danube swells, the pumping station springs into action to protect thousands of homes in Floridsdorf and Donaustadt. This system has proven its worth time and again, but now the city is taking its defenses to the next level.
On a normal day, Vienna moves about 600 to 2,000 liters of wastewater per second from the 21st and 22nd districts under the Danube to the Simmering treatment plant. During heavy rain, those volumes skyrocket. That’s when high-capacity pumps must kick in fast to keep streets and homes from flooding.
The Danube Island station already has six pumps that together can handle 40,000 liters per second. The new pump adds another 15,000 liters per second, giving the station even more power to manage sudden surges.
When the new pump is fully commissioned, it will mark the culmination of nearly 60 years of planning. The pumping station was built as part of the Improved Flood Control on the Danube in Vienna Project, launched in 1969. That project didn’t just create the station – it reshaped the river itself. The New Danube was excavated as a flood relief channel, and the material was used to form Danube Island.
Even then, planners anticipated that rainfall would become more extreme. They left space inside the station for future upgrades. That time has now come.
The new pump is a giant: 8.4 meters tall, weighing 24 tons, and capable of moving 15,000 liters of water every second. To put that in perspective, it could empty an Olympic swimming pool in under three minutes – or a backyard pool in just about three seconds. This makes it Europe’s most powerful rainwater pump of its kind.
It was designed, manufactured, and installed by ANDRITZ, drawing on more than 170 years of expertise in pump engineering. The choice of ANDRITZ was driven by the project’s extreme requirements: high demands on start/stop operation under the most adverse conditions meant that a standard solution simply wouldn’t suffice. Instead, a technically optimized pump tailored to the customer’s needs was essential to guarantee reliability when it matters most.
Tine Kocbek
Senior Project Manager, ANDRITZ Pumps
Work on the upgrade began in 2024, following a commitment by Vienna’s leadership to strengthen flood defenses. The project doesn’t stop at adding a seventh pump – it’s a full modernization. Hydraulic gates, pressure valves, ducting, frequency converters, and software integrations are all being updated. The building itself is getting new insulation, an external sunshade, and a green roof that will later host solar panels.
Fitting a pump this size into an existing facility is no small feat. The station had to remain operational throughout the process, ready to respond to any storm. Engineers faced a tight squeeze – just three centimeters of clearance through the main entrance. Every step, from transport packaging to lifting and positioning, required millimeter-level precision.
As Tine Kocbek explained: “Installing in an operating plant demands precise planning and a perfectly coordinated process. Millimeter accuracy is essential to ensure the pump is leak-tight and functions smoothly.”
Some might wonder why invest in equipment that will only run for short periods each year. But climate variability is changing the odds. Extreme rainfall events are becoming more frequent and more intense, and urban networks need redundancy and surge capacity to avoid cascading failures. Vienna’s strategy has always been forward-looking: anticipate risks, maintain systems, and upgrade before disaster strikes.
For residents of Floridsdorf and Donaustadt, the benefits are clear: shorter flooding periods, reduced overflow risk, and faster recovery when storms hit. For operators, the system gains precision and buffer capacity, ready to respond automatically when sensors detect rising flows. Within minutes of a cold start, the impeller can ramp up to 300 revolutions per minute.
With up to 15,000 liters of water being sucked through the pump every second, the strain on the impeller can be enormous. To ensure reliability well into the second half of the 21st century, ANDRITZ engineers designed every component – from the impeller and housing to the shaft seal – for a service life of 50 years, even under emergency conditions with abrasive, high-speed flows. This includes wear-resistant stainless steels, multi-layer coating systems on exposed surfaces, and optimized bearing arrangements to minimize mechanical losses.
How much use will it see in that time? Based on the likely frequency of heavy rainfall in the region, the new pump is only expected to operate for about 50 hours per year. That may sound like an overkill, but in those rare hours, it protects thousands of homes and lives – proof that resilience is built for the moments that matter most.
| Design: | ANDRITZ Vertical Line Shaft Pump |
| Impeller: | 1,72m |
| Head: | 11,1m |
| Flow Rate: | 15.000 l/sec |
Hydraulic design
This new vertical line shaft pump has a specially developed impeller and housing that are designed for extreme pressure surge conditions. The optimized blade geometry reduces turbulence and the risk of cavitation. Reinforced flow channels ensure stable operation even at 15,000 l/s. Improvements in hydraulic efficiency reduce energy consumption during peak loads.
Highly efficient drive and motor system
To accelerate from standstill to 300 rpm in a matter of minutes, the pump uses a high-torque, vibration-optimized drive system:
Benefits:
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