Recirculating rain water is pumped to the roof to free fall through a round hole at up to 37,850 liters (8,330 imp gal; 10,000 U.S. gal) per minute to a basement-level pool. An acrylic funnel at the bottom prevents splashing and insulates the sound of the cascade.

The "Rain Vortex" at Jewel Changi Airport in Singapore is the world's tallest indoor waterfall, and its operation is a marvel of hydraulic engineering and architectural design. The water falls from a circular opening in the glass-and-steel "toroidal" (doughnut-shaped) roof, dropping seven stories (40 meters) into a deep basin below. The system is a closed-loop recirculating system, meaning the same water is used repeatedly. When the water hits the catch basin at the bottom, it is filtered and pumped back up to the roof through massive pipes hidden within the building's structural columns. During Singapore's frequent heavy rainstorms, the system is designed to harvest rainwater; the roof acts as a giant funnel, collecting the water and integrating it into the waterfall, with any excess being diverted to storage tanks for use in the airport's irrigation systems. At night, the waterfall serves as a circular projection screen for a light and sound show, where high-powered projectors use the falling mist and water droplets as a medium to create 360-degree holographic-style visuals.