Urban water crises driven by elites' unsustainable consumption

The study addresses why and how urban water crises arise and disproportionately impact disadvantaged populations. It challenges depoliticized, technocratic explanations that attribute crises mainly to urban growth and climate change, arguing instead that social power asymmetries and heterogeneity shape both vulnerabilities and outcomes. The authors conceptualize urban water crises as social-environmental extremes driven by unequal control over and redistribution of water within cities. They propose to quantify the role of social inequalities in domestic water use and drought responses by developing a model that disaggregates consumption across social groups, using Cape Town—a highly unequal, drought-prone metropolis—as a case study.

Prior work often links rising urban water demand to urban expansion and population growth, while framing climate change as the key threat to freshwater availability. Physical and engineering sciences have advanced methods to quantify anthropogenic pressures on hydrometeorological hazards, yet such analyses frequently overlook how power relations and social heterogeneity determine crisis dynamics and vulnerability. Critical social science scholarship explains urban water crises as products of asymmetric power relations, politics, and historical processes that govern access, control, and redistribution of water. This work integrates these perspectives, moving beyond averages to examine unequal consumption and resilience across social groups.

The authors develop an interdisciplinary system-dynamics model to quantify unequal human–water interactions and their long-term impacts on an urban water system. Households are the basic units, reaggregated into five social groups per Cape Town’s Socio-Economic Index: elite, upper-middle income, lower-middle income, lower income, and informal areas. Social power is represented through parameters affecting access and consumption. Total household water use is split into basic needs and amenities; basic needs are met via public water (surface reservoirs), while amenities vary by income (gardens, pools, car washing). Access to private sources (household boreholes, rainwater, bottled/spring water) is modeled for higher-income groups; informal dwellers lack private source access. Drought awareness and municipal restrictions (including tariff increases) modify consumption behaviors over time. The urban water balance tracks reservoir storage, withdrawals, environmental flows (20% of monthly inflow), spill releases, and evapotranspiration (temperature-based). Operational rules define withdrawals and spillway releases. Private water demand depends on awareness, convenience, and distance to sources; public demand is the residual of total minus private demand. The model runs at monthly time steps and is calibrated/parameterized using fieldwork (65 interviews, 5 focus groups, May 2019–March 2020), governmental reports, and literature. Hydrometeorological and demographic data (inflow, storage, temperature, precipitation, population, consumption) are sourced from South African governmental services and the City of Cape Town Open Data Portal. Scenario analysis compares: (1) baseline inequalities; (2) population growth at 2% per year; (3) climate change (+2 °C, −10% runoff); (4) increased unsustainable consumption by privileged groups; and (5) equal and sustainable consumption across all groups. Model evaluation includes structural validity tests, dimensional consistency, extreme condition testing, and behavioral validation: reservoir volumes NSE = 0.84; annual average consumption RMSE = 133 Ml d−1. Key simplifying assumptions include not explicitly modeling racial polarization, simplified runoff generation (no percolation/infiltration/groundwater dynamics), lack of observed group-wise consumption for validation, and focus on intra-urban dynamics.

- Consumption inequality: Elite (1.4% of population) and upper-middle (12.3%) households together consume 51% of the city’s water, while lower-income plus informal groups (61.5% of population) consume only 27.3%. - Per-household daily use (model estimates): Elite ≈ 2,161 L/HH/day; upper-middle ≈ 988.78 L/HH/day; lower-income ≈ 178 L/HH/day; informal ≈ 41 L/HH/day. Privileged groups devote most water to amenities; poorer groups use most water for basic needs. - Drought impacts (2015–2017): Municipal restrictions (e.g., 350 L/HH/day caps, tariff increases) disproportionately harmed low-income households. Lower-income daily consumption fell from ≈197 to ≈101 L/HH/day (−51%), threatening satisfaction of basic needs. Elite and upper-middle reduced from ≈2,542 to ≈1,604 L/HH/day and ≈1,103 to ≈699 L/HH/day, mainly by cutting non-basic uses; they retained sufficient water for basic needs. - Private source reliance: During and after droughts, privileged groups increased use of private boreholes. Post-drought private/public ratios rose up to ≈7.5% (elite) and ≈1.3% (upper-middle); informal and lower-income groups had ≈0.04% and 0%, respectively. - Resilience divergence: Privileged groups become more water secure post-drought (able to pay tariffs and retain private sources), while low-income groups face lasting insecurity and reduced resilience due to permanent tariff changes and lack of alternative sources. - Environmental risk: Expanded private borehole use risks a supply–demand cycle and aquifer depletion, threatening long-term groundwater availability. - Scenario analysis: Increased unsustainable consumption by privileged groups is more detrimental to the urban water balance than population growth or climate change alone. Climate change scenarios trigger greater private borehole reliance and groundwater depletion. An equal and sustainable consumption scenario reduces total use, alleviates pressure on reservoirs, and preserves aquifers, potentially averting severe outcomes like Day Zero.

Findings demonstrate that urban water crises are not solely products of hydrometeorological drivers or aggregate demand growth; they emerge from entrenched socio-political inequalities that enable elite overconsumption and marginalize poorer residents. Technocratic, supply- and price-focused measures can exacerbate inequities, as tariffs and restrictions disproportionately reduce low-income households’ access to basic water while elites offset constraints via private sources. Effective drought resilience requires proactive policies that address root causes: curbing non-basic luxury consumption, regulating and monitoring private abstractions, and ensuring equitable water allocation and affordability. Integrating critical social science insights with hydrological modeling reveals how power structures shape both demand patterns and adaptive capacities, underscoring that elite consumption can drive crises at least as much as climate change or population growth.

The study introduces an interdisciplinary system-dynamics model that disaggregates urban domestic water use by social group, showing that elite overconsumption can precipitate or intensify urban water crises. Using Cape Town as a case, it evidences severe inequality in water use, unequal drought burdens, and increased post-drought reliance on private sources among privileged groups with associated aquifer risks. Scenario analysis indicates that reducing inequality and limiting amenity-driven consumption substantially improves urban water sustainability relative to scenarios emphasizing supply or accommodating growth. The authors advocate reorienting water management toward political-economic paradigms that prevent overconsumption and inequity, aligning with degrowth perspectives. Future research could extend the framework to include explicit groundwater dynamics, inter-urban and rural–urban competition, intersectional (e.g., racial) dimensions of inequality, and validation with finer-resolution consumption data.

- Social dimensions: The model focuses on socioeconomic inequalities and does not explicitly represent racial polarization and intersectionality that shape access and vulnerability in Cape Town. - Hydrology simplifications: Runoff generation omits percolation, infiltration, and groundwater dynamics; private source use does not feed back into reservoir storage in the model. - Data constraints: Lack of observed consumption data disaggregated by social group prevents direct validation of group-level water use. - Scope: Emphasis on intra-urban dynamics; rural–urban water competition and broader basin-scale interactions are not simulated. - Parameterization: Some parameters (e.g., awareness decay) are assumed uniform across groups; although sensitivity tests support robustness, heterogeneity may exist in reality.