An analysis of risk perception of using treated wastewater

Abstract

Treated wastewater is used as alternative source of water around the world. This can be explicitly, where water is harvested from wastewater infrastructure, or implicitly, where water is harvested from a water body that contains wastewater. The treated water can be used directly, as potable water, or indirectly, as an outdoor use for example. Wastewater treatment is a highly technical engineering process and suits the principles underpinning water providers. However, little research is the perceptions of treated wastewater. The heuristic is that treated wastewater is disgusting and risky. But is that really the case? And are practitioners' risks different from those of the general public? This thesis uses risk perception theory to examine common perceptions of treated wastewater. A framework of factors influencing risk was critically explored where knowledge, trust, sense of fairness, perceived control and other attitudes were modelled and compared to observations solicited by questionnaire. Statistical analysis shows that attitudes about treated wastewater of public and water practitioners have similar directions, except for questions related to power and information. It was found that members of the public view risks as slightly higher than the water practitioners. The results from a path analysis using structural equation modelling found trust and attitudes are negatively associated with risk perceptions, and sense of fairness is partly negatively associated with risk perception. 'Yuck factor' was a powerful tool for explaining people's opposition to treated wastewater and strongly influenced risk perception. Practitioners, as well as public, were subject to the 'yuck factor', but its influence was less clear suggesting familiarity with the concept leads to a perception of reduced risk. The contribution of this thesis is twofold. Firstly, this thesis adds to the debate on risk perception of treated wastewater building on the limited research that has considered risk and treated wastewater. The models compare public and water practitioners risks and added to discussions of the 'Theory of Planed Behaviour' to understand acceptance of technologies. Secondly, the thesis provides a reflection on the risk perception framework itself. The framework consists of many factors which was challenging to implement in a meaningful way. Nevertheless, it proved useful for starting a conversation about treated wastewater with both the public and practitioners which is a conversation set to continue with purported changes in populations and climates.