Global Assessment of Wastewater Irrigation: Understanding Health Risks and Contributions to Food Security Using an Environmental Systems Approach

EPA Grant Number: FP917505
Title: Global Assessment of Wastewater Irrigation: Understanding Health Risks and Contributions to Food Security Using an Environmental Systems Approach
Investigators: Thebo, Anne Louise
Institution: University of California - Berkeley
EPA Project Officer: Lee, Sonja
Project Period: August 16, 2012 through August 15, 2015
Project Amount: $126,000
RFA: STAR Graduate Fellowships (2012) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Fellowship - Civil/Environmental Engineering


Rapid urbanization without concomitant improvements in wastewater treatment infrastructure in developing countries has led to the widespread contamination of surface water sources, which downstream farmers rely on for irrigation. At present, 90 percent of the world’s wastewater receives no treatment before it is discharged to the environment. Paradoxically, these same flows concurrently pose health risks and provide a reliable, nutrient rich water source for peri-urban farmers. The overarching objectives of this research include: (1) quantifying the global extent of de facto reuse of untreated wastewater for irrigation; (2) understanding how the drivers and health risks associated with this practice vary spatially; and (3) characterizing the role of wastewater irrigation in global food security and integrated water resources management strategies.


Wastewater irrigation inherently is a local practice with global implications. A multitude of case studies document irrigation with untreated wastewater in 158 cities, but the majority of case studies is limited to four countries: Mexico, India, Pakistan and Vietnam. Several recently released spatial datasets provide a unique opportunity to estimate quantitatively the extent of wastewater irrigation with dramatically lower computational complexity, increased accuracy and in less time than was previously possible. Through the development of spatial models within an environmental systems framework, the four major phases and key activities of this research include: (1) mapping and characterization—quantifying the global extent of wastewater irrigation followed by extensive validation; (2) defining typologies of wastewater irrigation—understanding how the drivers and use of untreated wastewater in agriculture varies across contexts; (3) health risk assessment— differentiating spatial variation in health risks between typologies of wastewater irrigation; and (4) contributions of wastewater irrigation to food security and water management—understanding the role of wastewater irrigation in peri-urban food production.

Expected Results:

This research will quantify the extent of de facto reuse of untreated wastewater at the global scale. Through the integration of multiple existing spatial data sources, this project will produce rigorous analyses assessing the relationship between wastewater irrigation, health, fecal contamination in surface water sources, water resources allocation and urban food security. The inherent flexibility in the spatial models being developed for this project allows for the inclusion of additional modules and higher resolution datasets, as they become available. Examples of additional analyses that could be built onto this existing framework in the future include an assessment of the water quality impacts of different sanitation interventions, nutrient production and reuse potential, changes in wastewater irrigation over time and the role of wastewater in mitigating the impacts of water scarcity.

Potential to Further Environmental/Human Health Protection

Conspicuously absent from the Joint Monitoring Program’s definition of improved sanitation facilities is the provision for treatment of accumulated human waste from “improved” sanitation facilities. Such an approach to sanitation planning disregards the implications of sanitation infrastructure choice on downstream communities, especially farmers reliant on surface water sources for irrigation. By quantifying the extent of irrigation with untreated wastewater at the global scale, this research not only draws attention to the need for integrated wastewater and water resources management but also provides planners and policy makers with rigorous, concrete data on the drivers and health risks of this practice at scale. This research fills these key knowledge gaps through its systemslevel analysis of the extent, drivers and risks of wastewater irrigation across heterogeneous water resources, agricultural, economic, infrastructural and ecological contexts.

Supplemental Keywords:

wastewater irrigation, wastewater treatment, spatial models

Progress and Final Reports:

  • 2013
  • 2014
  • Final