By Celeste Morgan, Australasia Integrated Water Management Lead, Arup
Nowhere are the realities of the climate crisis clearer than in the water sector. From droughts, floods and storm surges, to heatwaves, 90 per cent of climate impacts play out in water. For cities aiming to be resilient, sustainable and liveable, water must be at the centre of how we plan, design, and manage our urban environments.
Integrated Water Management (IWM) is not just a technical solution to climate impacts – it is a strategic approach to futureproofing our cities. It breaks down the silos of stormwater, wastewater and water supply management to create holistic, place-based systems that are more resilient, more circular, and better aligned with community values and environmental realities.
The most successful projects don’t treat water as a constraint; they see it as an enabler – of green infrastructure, urban cooling, biodiversity, better design outcomes and stronger community connection. And through strategic use of data, governance and design, IWM can make that transformation real.
The case for integrated water management
The traditionally segmented management of urban water has come back to bite us in many ways. Dividing the management of water limits our ability to find innovation and efficiencies in the broader water system. Drawing on nature, IWM prioritises an interconnected approach, bringing together all aspects of the water cycle in a unified, collaborative way.
At its core, IWM supports:
- Place making: Embedding water into the identity of a place through green infrastructure, water features, or restored waterways enhances livability and wellbeing.
- Circularity: Tapping into alternative water sources like treated stormwater or wastewater supports sustainable supply and reduces waste.
- Resilience: A unified approach can reduce flood risk, ensure water security and support environmental health in a changing climate.
- Stewardship: Improving collaboration across councils, communities and catchments aligns efforts, unlocking funding and delivering shared outcomes.
Each of these pillars is essential to navigating the climate uncertainty that lies ahead; but more than that, they help us unlock hidden value in our cities.
Reframing the urban water challenge as an opportunity
Urban environments generate enormous volumes of stormwater, and our wastewater systems continue to produce recoverable resources. Yet, far too often these flows are treated as problems – something to be removed, treated and forgotten.
What if we flipped that thinking? Instead of seeing stormwater and wastewater as waste streams, IWM reframes them as assets. Stormwater can recharge groundwater, cool streets and irrigate green space. Wastewater can be treated and reused to support non-potable uses or industrial processes. And when these systems are designed with intent, they can deliver co‑benefits for climate resilience, biodiversity, heat mitigation and water literacy.
This is not theoretical. Today, cities around the world are putting this philosophy into practice, turning run-off into a resource, and water infrastructure into tools for placemaking. Melbourne, Australia, has a city-wide IWM plan and already harnesses 10 per cent of the stormwater and wastewater that the city produces, utilising these resources in homes, and to irrigate green spaces and support agriculture – with ambitions for much more.
Harnessing digital tools for place‑based water solutions
Another key to unlocking the full value of IWM lies in digital technology. With the right tools and data, we can move from reactive, one-size-fits-all approaches to smarter, place‑specific planning.
Digital tools help councils and utilities to:
- understand where water-sensitive urban design (WSUD) will deliver the most benefit
- engage communities with their local water story
- plan infrastructure upgrades with future climate impacts in mind
- visualise alternative water sources and make the business case for investment.
These tools not only improve planning efficiency, but they also empower stakeholders across organisations – from technical specialists to community planners – to make informed, strategic decisions.
Case study: strategic prioritisation for Water-Sensitive Urban Design in Melbourne
Melbourne’s urban landscape – like many in Aotearoa New Zealand – is under growing pressure from increasing heat, urbanisation and the need to manage more intense rainfall events. Recognising these challenges, the City of Melbourne committed to embedding WSUD into its streetscape retrofits – using infrastructure such as rain gardens, permeable pavements, and passively irrigated trees to manage stormwater and support greening.
But the question remained: Where should WSUD be prioritised to deliver the most value?
To answer this, our team, comprising water engineers, digital specialists and geospatial analysts, worked with the City of Melbourne to co-design a digital Strategic Prioritisation Map. This interactive tool assesses every street across the municipality using a three-layered methodology:
- Suitability: The map identifies suitable locations for WSUD and areas where a retrofit would not be feasible or would be costly. The City of Melbourne provided detailed geospatial data of the drainage network, while light detection and ranging reports gave topographical data to understand water flow, micro-catchments, and road slopes.
- Priority: Each location is scored in terms of priority to ensure investments in WSUD will deliver the greatest value. To achieve this, it was important to understand if the area was a priority for treating stormwater, managing downstream flood risk or combating urban heat.
- Typology: The map presents a range of suitable WSUD typologies for consideration through design. For example, it identified streets where the footpath was too narrow for a behind-kerb feature, where WSUD could integrate with parking or traffic-calming islands in low-speed zones.
The tool integrates into the city’s geographic information system, giving planners an intuitive platform to identify opportunities, explore typologies and align projects with broader environmental goals. Generalists can scan the map for high-level insight, while specialists can dive into the data layers to inform detailed design.
This tailored, place-based approach to IWM empowers the City of Melbourne to:
- prioritise WSUD where it delivers maximum impact
- optimise investment by targeting high-benefit, low‑cost sites
- align water projects with broader objectives like tree canopy expansion and heat mitigation.
This work is ongoing, as new data becomes available and as the prioritisation map is expanded to additional areas. It’s a strong example of how digital innovation, collaboration and systems thinking can come together to make water resilience tangible.
Lessons for New Zealand: creating our own water story
New Zealand cities face many of the same challenges and opportunities as Melbourne, such as growing urban populations, constrained water supply, climate pressures and financial constraints on local authorities.
This is where the principles of IWM become particularly powerful. They help us ask the right questions in order to tailor a solution to each place, including:
- What does this community value in its water story?
- Where can we deliver multiple benefits with one investment?
- How can we work together across organisations and mandates?
- What data and digital tools do we need to support informed decisions?
IWM is not a checklist; it’s a mindset shift. It’s about thinking differently about water, embracing complexity and designing for long-term value.
Unlocking the full potential of urban water
To meet the dual challenges of climate adaptation and urban growth, we need integrated, adaptive, and collaborative approaches to water. IWM offers a clear path that turns constraints into opportunities, and silos into systems. The key is to start local, think integrated and design for resilience.
When councils, water agencies and communities come together around a shared vision for water, the possibilities are vast. Whether it’s retrofitting stormwater infrastructure, building digital planning tools, or advancing circular water economies, every success begins with asking: How can water be part of the solution?