Study Links Unsafe Water to Global Food Insecurity Across 121 Countries

Research published in Nature Food finds that lack of access to clean drinking water significantly increases food insecurity risk in both low- and high-income nations, prompting calls for coordinated global policy action

A major new global study has found that people without access to clean drinking water are significantly more likely to experience food insecurity and food safety risks, adding weight to growing calls for governments and international organizations to address water and food challenges as a single, interconnected crisis rather than as separate policy areas.

Why Water and Food Security Are Increasingly Linked

Water and food security have traditionally been treated as distinct policy domains, managed by different institutions, funding streams, and international frameworks. Water security efforts have typically focused on infrastructure, sanitation, and public health, while food security programs have centered on agricultural production, nutrition, and supply chains. This institutional separation has persisted even as researchers have increasingly recognized that the two issues are deeply intertwined at the household and community level.

That separation is becoming harder to justify as climate change, population growth, and mounting pressure on freshwater resources reshape risk patterns worldwide. Public health experts have repeatedly warned that droughts, extreme weather events, and shrinking freshwater supplies are likely to make both water and food insecurity more common in the coming decades, with low-resource communities expected to bear a disproportionate share of the impact. Against this backdrop, understanding exactly how water insecurity and food insecurity interact has become an urgent research priority.

Study Details and Methodology

The new study, published in the journal Nature Food, was conducted by a team of researchers from the University of Southern California (USC) and the International Water Management Institute (IWMI), drawing on combined expertise in water systems, food security, and public policy.

Researchers analyzed survey data from the Lloyd’s Register Foundation World Risk Poll, one of the largest global surveys of its kind, which included responses from 124,003 individuals across 121 countries spanning all income levels — from low-income to high-income nations. This broad geographic and economic scope allowed researchers to examine whether the relationship between water and food insecurity held consistently across vastly different economic and infrastructural contexts.

Key Findings

The analysis found that, globally, roughly 10% of respondents reported lacking access to clean drinking water, food, or both — a figure that held true even in high-income countries, where such deprivation is often assumed to be rare. Notably, the data showed compounded effects of lacking both clean drinking water and food safety not only in low-income regions such as eastern Africa, but also in high-income regions including northern America.

Wändi Bruine de Bruin, the study’s lead author and Provost Professor of Public Policy, Psychology and Behavioral Science at the USC Price School of Public Policy, said the findings challenge assumptions about who is affected by these overlapping risks. She noted that even in wealthy countries, individuals who lack access to clean drinking water are far more likely to also lack access to food.

Why the Two Crises Are Connected

Researchers pointed to several interconnected reasons why water and food insecurity so often occur together. Broader environmental and structural factors — including poor infrastructure, climate change, poverty, homelessness, and conflict — tend to affect both water and food access simultaneously, rather than one in isolation.

There are also more direct mechanisms at play. Without access to clean drinking water, safely preparing food can become difficult or, in some cases, impossible. Additionally, when individuals or households are forced to spend more time and money securing food, they often have fewer resources left over to secure clean water — creating a cycle in which scarcity in one domain intensifies scarcity in the other.

Calls for Coordinated Policy Action

Rachael McDonnell, Deputy Director General at IWMI and a co-author of the study, said water insecurity, food insecurity, and food safety are too often treated as separate challenges, and are frequently — and incorrectly — assumed to be problems limited to low- and middle-income countries. She argued that addressing this interconnected crisis will require global, national, and local institutions to move beyond the structural and political divisions that have historically fragmented coordinated action across water and food policy.

The study calls for expanded investment in clean water infrastructure, sanitation systems, and community-based public health programs, with particular attention to vulnerable and underserved populations. Researchers also urged policymakers to strengthen collaboration across water, food, and related sectors — including in wealthy nations, where the issue has often been overlooked — by breaking down the institutional barriers that have traditionally kept these policy areas siloed.

Beyond funding and infrastructure, the study emphasizes a shift in how these challenges are conceptualized and measured. Researchers recommend that water insecurity, food insecurity, and food safety risks be assessed collectively — both when identifying community needs and when designing and evaluating policy interventions — rather than being tracked and addressed as unrelated issues.

Broader Implications

The findings contribute to a growing body of research establishing that access to clean drinking water underpins not just public health and sanitation, but also nutrition, food safety, and broader economic stability. Researchers expressed hope that the study will encourage policymakers and international organizations to adopt more comprehensive strategies that protect water and food systems together, rather than through fragmented, sector-specific approaches.

The study’s authors concluded that access to clean drinking water is a basic human necessity, and that ensuring safe water access is critical to improving food security, reducing health risks, and supporting healthier communities worldwide.