The first thing most people think when it rains in a city is not wonder at the gift of water, but worry. Will the drains cope? Will the road outside flood? Will the river break its banks again? For decades, stormwater has been treated as a problem to be channelled away as quickly as possible, an inconvenience to pipes and pumps. Yet slowly, a new vision is taking hold. Stormwater is no longer just waste to be managed. It is being reimagined as a valuable urban asset.
Water way at Bishan - Ang Mo Kio park
From grey to green, and now to smart
The history of urban water is largely a history of control. Victorian engineers built vast networks of pipes and culverts to protect cities from disease and flooding. Their focus was efficiency: remove rainwater fast, keep it separate from drinking water, and discharge it into the nearest river. That model worked for a time, but today the cracks are showing. Climate change is intensifying rainfall, cities are expanding, and infrastructure built a century ago is under strain.
Over the past two decades, a new approach has emerged: water-sensitive urban design. Green roofs, rain gardens, permeable pavements, swales and wetlands now soften hard landscapes and slow the flow. They reduce flood risk, recharge groundwater, and create pockets of biodiversity in dense cityscapes. This has been a quiet revolution, but it is only the first stage. The next is making these systems not only green, but smart.
The rise of digital water
Cities are complex organisms. They change hour by hour, street by street. Rainfall can vary dramatically across a neighbourhood, and water quality can shift with a single discharge. Traditional infrastructure, built on averages and assumptions, is poorly suited to such dynamism. Enter digital water technologies.
IoT sensors embedded in drains and watercourses can track flow in real time. Predictive models, fed by weather forecasts and historic data, can anticipate where floods are most likely. AI systems can then direct pumps, valves, or temporary storage to respond before a crisis occurs. At the same time, real-time monitoring of water quality can detect pollution spikes and trigger rapid interventions, protecting both ecosystems and public health.
For residents, this means a city that feels more responsive. Instead of waiting for the next big flood, authorities can act pre-emptively. Instead of blindly discharging stormwater, cities can capture and use it to irrigate parks, flush toilets, or top up aquifers. Stormwater becomes part of a circular water system, not a burden on it.
Lessons from abroad
Australia has long been a pioneer in water-sensitive design. Melbourne’s “Water Sensitive City” strategy integrates green infrastructure with smart controls. Pilot projects use real-time monitoring to manage rainwater harvesting tanks and wetlands, optimising them for both stormwater retention and ecosystem health. This means water can be held back during storms to reduce flooding, then released slowly to support river ecology once the danger has passed.
Singapore offers another model. The city-state’s Smart Water Grid uses thousands of sensors to monitor pressure, flow and quality across its entire network. Although focused primarily on potable water, the same approach is being applied to stormwater drainage and reservoir management.
One of the clearest examples of this philosophy is Bishan-Ang Mo Kio Park. Once a sterile concrete canal designed to rush water away, it has been transformed into a naturalised, meandering river running through a public park. Smart controls now manage upstream flows, allowing the river to expand during heavy rain without threatening nearby homes, then retreat into a narrower channel during dry spells. The result is not only effective flood protection, but also a thriving public space where families picnic, joggers run beside dragonflies, and biodiversity flourishes in the heart of the city. Bishan shows how smart systems and natural landscapes can be knitted together to serve both people and nature.
🌿 Case Study: Bishan-Ang Mo Kio Park, Singapore
Before
A straight, concrete stormwater canal built to move water quickly out of the city.
No biodiversity, no amenity, and little resilience to sudden heavy rainfall.
After
Transformed into a 3 km meandering naturalised river within a 62-hectare public park.
Integrated landscaping creates habitats for fish, birds, and insects, while offering space for recreation and community life.
Key Lessons for Future Cities
Smart controls upstream allow the river to safely expand during storms, then shrink back during dry weather. Stormwater can be reimagined as both an ecological and social asset.
Pairing smart flow controls with naturalised design allows for flexible flood management.
Public engagement grows when water is visible, accessible, and part of daily life, rather than hidden underground.
Takeaway: Bishan shows that smart water infrastructure is not just about technology. When combined with bold design and natural processes, it can turn a liability into one of the most loved public spaces in a city.
Closer to home, the Netherlands is experimenting with “digital twins” of entire cities, allowing planners to simulate storms, sea level rise and infrastructure responses before making costly investments. These models are not just planning tools. They increasingly inform real-time operations, allowing engineers to test scenarios virtually before opening a sluice gate or diverting flow.Designing with nature, guided by data
A cross-section of a water-sensitive neighbourhood: rooftop rainwater harvesting tanks, green street swales, and wetlands all feed data into a central AI dashboard. Together, natural and digital systems manage stormwater more adaptively, turning rainfall into a resource rather than a risk.
The common thread in these examples is that smart technology does not replace the natural world. It complements it. A rain garden still slows and filters water. A wetland still provides habitat for dragonflies and frogs. But with sensors and predictive tools layered on top, these systems can be tuned to perform better. It is like giving nature an earpiece into the digital conversation of the city.
This is important because urban design cannot rely on technology alone. No algorithm can replace the cooling shade of a tree or the social benefits of a park. But by knitting together natural and digital layers, cities can become more adaptive. When heatwaves and flash floods arrive more often, adaptation is no longer optional.
A broader vision of urban resilience
Stormwater management may sound like a technical detail, but it is in fact a window into how we imagine our cities of the future. Do we continue to build rigid systems that crack under pressure, or do we create flexible, adaptive networks that learn and respond?
Imagine a neighbourhood where rainwater is captured on every roof, filtered through pocket wetlands, monitored in real time, and then reused locally. Streets stay cooler, biodiversity thrives, and residents feel part of a water-sensitive community. This is not utopian fantasy. The building blocks exist today, scattered across pilot projects and research programmes. The challenge is scaling them, embedding them into planning systems, and ensuring they are affordable for all.
Cautious optimism
There is reason for optimism. Costs of sensors and digital tools are falling, while public awareness of flooding, drought, and pollution is rising. The convergence of green infrastructure with smart technology offers one of the most compelling pathways to resilient cities.
Yet there is a caveat. Technology can easily become a distraction, a shiny solution that papers over deeper issues of governance, funding, and inequality. A smart drain is of little use if the community it serves is not engaged, or if decisions about water are made without transparency. Cities of the future must be co-designed with people as well as with nature.
The role of technology, then, is as an enabler. It helps us listen to the water, anticipate risks, and use resources wisely. But it does not absolve us of the harder task: designing cities that are fair, inclusive, and ecologically sound.
So the question is not whether smart stormwater systems will shape the next generation of cities. They already are. The real question is whether we will use them to build places that are not only safer and more efficient, but also more humane.
