Urban Sprawl’s Hidden Burden: How City Expansion Erodes Water and Sanitation Access
Across the globe, the rapid growth of cities has become a defining characteristic of the 21st century urban landscape. As urban areas extend their boundaries, particularly into regions characterized by scarce rainfall and limited water retention, new challenges arise directly impacting the delivery of essential services like water and sanitation. A groundbreaking study recently published in Nature Cities delves into the complex relationship between urban form and access to water, shedding critical light on how sprawling urban development compromises water infrastructure and affordability.
The investigation analyzed over 100 cities spanning Asia, Africa, and Latin America, regions that collectively house a rapidly growing population and face stark water resource constraints. The researchers pioneered a novel approach by creating comparable urban layouts for these diverse cities, enabling an unprecedented cross-regional study on how city shape and size influence residents’ access to water and sanitation services. This method afforded the ability to quantify subtle yet impactful urban characteristics that often go unmeasured in traditional city planning assessments.
Central to the study’s methodology was the concept of remoteness, defined as the geographic distance from any given location within the city to its central core. The city center, representing the hub of infrastructure, economic activity, and governance, inherently influences resource distribution. The team also introduced a complementary metric, sparseness, which synthesizes remoteness across the entire population to reflect how dispersed a city’s inhabitants are from this core. By doing so, they could relate population settlement patterns directly to infrastructural and service accessibility.
One of the foundational findings is that proximity to the city center correlates strongly with higher average incomes and better access to critical infrastructure such as sewage systems and piped water. In contrast, locales farther from the core experience severe disadvantages — limited infrastructure, reduced sanitation coverage, and lower economic opportunity manifest together in a damaging cycle. This pattern suggests spatial inequality entrenched by urban design itself, reinforcing socio-economic stratifications through geography.
Equally telling is the impact of a city’s overall sparseness. Sprawling cities—those where the population is more diffusely spread—exhibited a propensity toward higher water tariffs and diminished access to fundamental services. The researchers attribute this increase in service costs to the inefficiency of delivering infrastructure across wider areas with lower population density. System extensions over greater distances require disproportionate investment and operational complexity, further burdening residents financially.
The implications of these findings extend beyond academic discourse, resonating deeply within policy and urban planning circles. Water utility providers in sprawling cities face operational hurdles that not only raise costs but also limit coverage expansion, thereby perpetuating service gaps. This dynamic is particularly acute in regions with climatic stressors such as insufficient rainfall, amplifying the urgency for optimized service delivery models tailored to evolving urban footprints.
Projecting into the future, the study explored how urban expansion scenarios could alter access to water services. Using sophisticated modeling, the researchers evaluated three distinct growth patterns: compact, persistent, and horizontal expansion. Compact growth prioritizes increased density and vertical development within existing urban boundaries, while persistent growth maintains current trajectories, and horizontal growth emphasizes outward sprawl.
The results were striking. Under a compact growth scenario, approximately 220 million more people could potentially gain access to piped water, and 190 million would see improved access to sewage services compared to if cities continued expanding horizontally. This visualization powerfully underscores how strategic urban planning that encourages density and infill can dramatically elevate infrastructure reach and equity.
Conversely, if cities continue their horizontal expansion along current trends, the challenges of provisioning water and sanitation will likely intensify. Not only will costs escalate, but service disparities will deepen as more residents cluster in hard-to-reach, infrastructure-deficient zones. This unsustainable trajectory threatens to undermine progress toward global development goals centered on universal access to clean water and sanitation.
The research also illuminated interdependencies between urban form and socio-economic variables. Neighborhoods closer to the center did not merely enjoy better infrastructure but also tended to feature higher income levels, a phenomenon that feeds into a dual-edged feedback loop. Elevated incomes fund superior services and increased property values, which, in turn, attract investment in infrastructure, creating enclaves of affluence within cities. Meanwhile, peripheral populations face the compounded risk of economic marginalization and infrastructural neglect.
This evidence challenges urban planners and policymakers to rethink conventional development paradigms. It suggests that growth management strategies must integrate water service logistics and affordability concerns upfront, rather than treating them as secondary outcomes. Proactive policies that foster compactness may represent one of the most effective levers in reducing urban inequalities and mitigating the environmental pressures imposed by sprawling settlements.
Technologically, this work calls for innovation in how water and sanitation networks are designed to cope with less compact urban environments. Smart infrastructure solutions, decentralized water treatment units, and demand management could help mitigate problems in sprawling cities, but these require investment and coordination that many low- and middle-income urban centers struggle to afford. Thus, policy frameworks need to incentivize such innovations while ensuring affordability.
Climate change further compounds the complexity of these dynamics. Cities expanding into dry regions face declining rainfall alongside expanding populations, tightening the constraints on water supply. Sustainable urban form, therefore, is not only a matter of social equity but a critical component of climate resilience strategies. Failing to address urban form risks locking vulnerable cities into a trajectory of escalating water scarcity and exposure to sanitation-related health hazards.
Moreover, this study invites a broader reflection on the role of urban morphology in facilitating or hindering sustainable development. Urban sprawl is often glibly viewed through an environmental lens focused on land use or transportation. However, this research affirms that the shape of a city profoundly influences essential service accessibility and the economic well-being of its residents. Understanding these links is vital for designing cities that are both livable and just.
The comprehensive methodology underlying this global comparative analysis represents a significant advance in urban studies. By harmonizing data across continents and urban contexts, the research provides a robust empirical foundation to advocate for policy shifts. It leverages spatial analytics and demographic weighting to move beyond anecdotal evidence, enabling targeted interventions tailored to specific urban forms.
As cities worldwide grapple with relentless urbanization, these insights offer a clarion call to reimagine growth trajectories mindful of water equity and affordability imperatives. Compact urban expansion emerges not merely as a theoretical ideal but a pragmatic pathway to ensuring millions gain access to fundamental infrastructure services. Harnessing this knowledge will require coordinated efforts from governments, planners, researchers, and local communities alike.
In summary, the relationship between urban form and water access is both profound and actionable. This study demonstrates that sprawling, sparse urban areas hinder access to clean water and sanitation, increasing service costs and entrenching inequalities. By contrast, denser, more compact urban growth patterns can dramatically enhance infrastructure reach and affordability, benefiting hundreds of millions. Accordingly, urban planners and policymakers have a clear mandate to embed compactness into growth strategies to foster equitable, resilient, and sustainable cities.
Subject of Research: The study investigates the effects of urban form—specifically remoteness and sparseness—on water and sanitation access in over 100 cities in Asia, Africa, and Latin America.
Article Title: Urban sprawl is associated with reduced access and increased costs of water and sanitation.
Article References:
Prieto-Curiel, R., Luengas-Sierra, P. & Borja-Vega, C. Urban sprawl is associated with reduced access and increased costs of water and sanitation. Nat Cities (2025). https://doi.org/10.1038/s44284-025-00338-3
Image Credits: AI Generated
DOI: https://doi.org/10.1038/s44284-025-00338-3
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