What goes on behind the world’s tallest indoor waterfall?

 November 2020

Standing at the nucleus of Jewel, the HSBC Rain Vortex stretches over seven floors, making it a prime attraction to visitors.


Standing 40 metres tall with water cascading down from the dome-shaped roof of Jewel Changi Airport (Jewel), the HSBC Rain Vortex is the world’s tallest indoor waterfall. This architecture marvel has been a centre of attention for many since Jewel opened doors in April 2019. 

However, many do not know the science behind the rain vortex. The Changi Journeys team followed the Jewel team to gain a deeper understanding on the 7-storey wonder.


How does the HSBC Rain Vortex work?

Take a closer look and you can see the pipes that channel water to the ring in the middle of the oculus.


To create that even circular flow of water down the Rain Vortex, there are structural features built into the exterior of the building. The “fins” outside the dome structure make up a network of pipes that channel water to the ring in the middle of the oculus. The oculus then distributes the water down the Rain Vortex and gives it an even complete circular effect.

The water stretches all the way from the roof, down to Basement 3 (B3), where the catchment area is. The water stored in B3 is then pumped back up around the perimeter of the building to the oculus, where the cycle repeats itself.

Cleaning and maintenance is done periodically to ensure that the Rain Vortex can circulate sparkling clean water all the time.


In accordance to the regulatory requirements, the Rain Vortex undergoes thorough cleaning periodically. During the cleaning, the Rain Vortex will be inoperable for up to a week. To ensure that the water meets the regulated quality limits and is safe to fall through the vortex, samples of the water are taken regularly to a lab for testing. 


Unbeknown to many, a pump room sits inconspicuously at the B3 car park of Jewel, where all the main pumps and controls for the Rain Vortex are located. Water is stored in the water tank behind the walls while the pipes and pumps are built around them. On rainy days, rainwater is also collected and stored at B3, before it is channeled back up to Level 5 into the oculus. When the tanks are full, excess water is used for irrigation or diverted to other uses.


Regular checks of the water pumps at the HSBC Rain Vortex keep the iconic waterfall running perfectly.


The pumps are like the muscles of the Rain Vortex, while the electrical panels are its brains. All the lights, audio, animation and media for the Light & Sound show are master-controlled here. The 12 projectors hidden within the Shiseido Forest Valley that surrounds the Rain Vortex are also manually powered on in the pump room.

The show is pre-programmed on the panels and manually controlled by an iPad via a dedicated wireless network at the Rain Vortex itself. 


Are there other interesting features of the Rain Vortex?


The black ring of water surrounding the Rain Vortex is the Reflective Pool, making it a perfect subject for an Instagram photo. Coins can sometimes be found in the pool as coin-tossing is thought to bring good luck. To discourage this behaviour, the team at Jewel cleans the Reflective Pool often to rid it of dirt as well as coins. 

The unique effect the Water Skin brings is mesmerising to the eyes, and also one of the most Instagrammable spots in Jewel.


The water that flows into the Reflective Pool continues downwards on to B1 and B2, forming the Water Skin acrylic column feature you see stretching across the two floors - another favourite social media spot for many.

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