Over the years, much research has attempted to unpack what drives public responses to water reuse, using a variety of approaches. A large amount of this work was captured by an initial review that covered research undertaken up to the early 2000s (Hartley, 2006). This paper showcases post-millennium evidence and thinking around public responses to water reuse, and highlights the novel insights and shifts in emphasis that have occurred in the field. Our analysis is structured around four broad, and highly interrelated, strands of thinking: 1) work focused on identifying the range of factors that influence public reactions to the concept of water reuse, and broadly looking for associations between different factors; 2) more specific approaches rooted in the socio-psychological modelling techniques; 3) work with a particular focus on understanding the influences of trust, risk perceptions and affective (emotional) reactions; and 4) work utilising social constructivist perspectives and socio-technical systems theory to frame responses to water reuse. Some of the most significant advancements in thinking in this field stem from the increasingly sophisticated understanding of the 'yuck factor' and the role of such pre-cognitive affective reactions. These are deeply entrenched within individuals, but are also linked with wider societal processes and social representations. Work in this area suggests that responses to reuse are situated within an overall process of technological 'legitimation'. These emerging insights should help stimulate some novel thinking around approaches to public engagement for water reuse.

Recent UASB-pilot plant and full scale experiences show that anaerobic pre-treatment is feasible for sewage and domestic wastewaters in tropical regions. This offers developing countries the unique opportunity to become completely self-sufficient in this respect. UASB-systems can be applied at very small and at very big scale, i.e. for off-site and (house and community) on-site treatment. Results obtained in pilot plant and full scale installations demonstrate that these systems are quite effective in removing and stabilizing organic pollutants at liquid detention times as low as 4 hrs, i.e. a BOD reduction up to 75-95 % can be achieved, while an almost complete treatment can be accomplished by combining the method with a small aerobic lagoon. Instead of consuming high grade energy, these systems produce energy. Moreover the excess sludge production is very low, while also the dewatering characteristics of the sludge are excellent.

This paper explores the value of involving citizens in the generation of knowledge in drinking water research. To this end, the significance of the ‘Freshness of Water’ citizen science project on the microbiological stability of drinking water was analyzed, supplemented with a series of expert interviews. In this project, citizens of Amsterdam participated in taking samples from their own kitchen tap and testing the water using test strips. The subsequent monitoring of bacteria revealed that the total number of bacterial species in all of the Amsterdam drinking water samples was high. For the participants, the presence of ten thousands of bacterial species in their drinking water, as well as the interpretation that this is perfectly normal and not a health concern, was obviously new. However, instead of causing concern or worry, this transparency clearly functioned as a strong confidence-inducing signal. A majority of the citizen scientists state that, as a result of their participation, their confidence in the quality of drinking water and the water company has increased. This study suggests that citizen science can raise the participant’s water awareness and that, with the appropriate support, non-professionals can make a valuable contribution to scientific drinking water research.

The governance dimensions of water reuse scheme development and operation, such as policies and regulatory frameworks, and public involvement and stakeholder collaboration, can serve to both facilitate and constrain wider adoption of water reuse practices. This paper explores the significance and underlying structure of the key governance challenges facing the water reuse sector in Europe. It presents empirical evidence from interviews and focus group sessions conducted at four water reuse schemes: an indirect potable reuse scheme at Torreele (Belgium), the urban reuse of treated municipal wastewater at the London Olympic Park (United Kingdom) and at Sabadell (Spain), and the reuse of agro-industrial effluent for irrigation at Capitanata (Italy). The findings underscore the importance of clarity in policy arrangements around water reuse, as well as of the financial competitiveness of reuse projects compared to alternative water supply options. Operators of water reuse schemes expressed a preference for water quality standards, which focus on appropriateness for use rather than over-emphasise the waters’ origin so that unnecessary treatment and costs can be avoided. Positive public support was widely acknowledged as an important factor in the success or failure of water reuse schemes. We conclude that constructive institutional relationships underpin many of the challenges faced by reuse scheme operators and that greater emphasis should be given to building confidence and gaining trust in water service providers through early identification of how governance regimes shape the viability of new schemes.