Given the scope of water and sanitation challenges posed by climate change and continued urbanization, potable water recycling is gaining traction as a means to expand urban water supply and decrease wastewater disposal into waterways. No longer regarded as a system by-product without value, planners increasingly consider wastewater a displaced resource in need of recirculation. The literature suggests that public perception and institutional barriers are the limiting factors to greater recapture and reuse of wastewater. Implicitly accepting water recycling as a sustainable alternative, much of the research is aimed at overcoming public opposition. However, the trend toward potable water recycling disrupts the normally hidden processes of urban water delivery, treatment, and disposal. In doing so, it provides a rare opportunity to contemplate taken-for-granted technologies of waterborne sanitation and to recognize alternative modes of managing human excrement, including composting toilets and dry sanitation.

In the coming decades, highly treated wastewater, known as reclaimed water, is slated to be a major element of municipal water supplies. In particular, planners propose supplementing drinking water with reclaimed water as a sustainable solution to the growing challenge of urban water scarcity. Public opposition is currently considered the primary barrier to implementing successful potable water reuse projects; nonetheless, public responses to reclaimed water are not well understood. Based on a survey of over 250 residents of Tucson, Arizona, this article assesses the relationship between trust in the professional institutions responsible for municipal water development and willingness to drink reclaimed water. Results demonstrate that public acceptance of potable reuse is contingent on trust in the authorities who influence design of sociotechnical systems for water supply and reuse—including water and wastewater utilities, regulators, consultants, academics, and elected local officials. Findings emphasize the highly interdependent social and political factors that inform personal decisions to support or reject potable reuse. The authors suggest that achieving greater acceptance of potable reuse will require bringing local and regional water policy in line with public values, as well as finding ways to incorporate these values into the planning process.

Ensuring water availability for multiple needs represents a sustainable development challenge globally. Rigid planning for fixed water supply and reuse targets with estimated demand growth and static assumptions of water availability can prove inflexible in responding to changing conditions. Formal methods to adaptively respond to these challenges are needed, particularly in regions with limited natural resources and/or where multiple uncertain forces can influence water-resource availability and supply reliability. This paper assesses the application of Scenario Planning in one such region-Tucson, Arizona, USA-over the coming 40 years, and highlights broader lessons for addressing complex interrelationships of water management, infrastructure development, and population growth. Planners from multiple OPEN ACCESSWater 2012, 4 849 jurisdictions and researchers identified ten key forces and prioritized three with the greatest uncertainty and the greatest impact for water and development planning: (1) changing demands based on potential future density, layout, and per capita water use/reuse; (2) adequacy of current water supplies to meet future demands; and (3) evolving public perceptions of water reuse including potential options to supplement potable water supplies. Detailed scenario modeling using GIS and infrastructure cost optimization is under development and is now beginning to produce results, to be discussed in future publications. The process has clearly demonstrated the value of Scenario Planning as a tool for bringing stakeholders into agreement over highly complex and historically divisive problems, and for prioritizing amongst diverse uncertainties. The paper concludes by characterizing possible outcomes for this case and draws lessons for other water scarce regions experiencing rapid development.

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