Water scarcity, due to climate variability and increased urbanization, has emerged as one of the most pressing problems in the 21st century [1
]. Agriculture is the sector which uses the largest share of water in most countries [2
], being currently responsible for 70% of water abstraction worldwide [4
], while irrigated land is expected to expand significantly during the next decades [5
The increasing gap between water needs and availability affects the ability to secure freshwater supplies and implies increasing provisioning costs for agricultural systems and actors, with potentially destabilising effects for markets. On the demand side, water consumption in the agriculture sector is expected to rise in the future due to different drivers, such as the intensification of agricultural production—mainly driven by population growth—and increasing standards of living (UNESCO, 2016; accessible at: https://unesdoc.unesco.org/ark:/48223/pf0000244041
). On the supply side, climate change will affect water resources in many ways: through extreme events (i.e., floods and droughts), by changing patterns and amounts of precipitation, or by affecting water quality through changes in runoff, river flows, and water retention. The severity and length of droughts will progressively increase [6
], especially in southern and Mediterranean Europe [7
Within the agriculture sector, the abovementioned trends encourage action to reduce pressure on water resources either by reducing water demand or by enhancing water supply. In the latter case, wastewater reclamation is viewed as a valuable opportunity on socioeconomic, policy, and environmental grounds. The socioeconomic argument is that it embeds significant (product and process) eco-innovation potential, putting into practice the concepts of reducing, reusing, and recycling in agriculture, which are gaining momentum through the concept of the Circular Economy [8
]. On policy grounds, the reuse of treated wastewater favours the competitiveness of the European Union (EU) water industry (Lisbon Strategy), is in line with the EU Common Agricultural Policy, and supports compliance with the Water Framework Directive (WFD-Directive 2000/60/EC) [9
] and the Sustainable Development Goals (SDG) (Johannesburg). Finally, on environmental grounds, together with favouring adaptation to climate change and reducing the need for water abstraction, wastewater reuse can contribute to reduce water eutrophication and/or chemical and microbiological contamination [10
]. Its returns also spread to non-water-scarce areas, benefiting greenhouses and providing, to some extent, renewable nutrients supplies [12
While wastewater reuse is not a novelty, globally, around 80% of water is not treated [13
] and only “15% of the generated wastewater and 41% of the treated wastewater are destined worldwide for agricultural irrigation” [14
]. In Europe, especially in the Mediterranean area [7
], despite water being an increasingly limited resource, its reuse is not widely employed [15
Amongst the barriers preventing its exploitation and hindering new investments (e.g., financial constraints, inadequate regulatory frameworks, engineering issues, etc.), several researchers have pointed out the importance of social acceptance and beliefs in influencing the implementation of new water projects or, more generally, the use of innovation [16
]. Several technical schemes have failed at the international level because of rejection by communities. Examples of factors potentially influencing people’s acceptance of recycling water schemes are represented by perceived risks and benefits, perceived control over the quality of water, trust in authorities, knowledge about the schemes, and personal feelings and emotions about these schemes [21
The existing literature tends to focus on water innovation issues from a macro-oriented perspective, rather than on micro-level evidence highlighting factors driving investments in wastewater treatment (WWT) technology and social acceptance [22
]. Additionally, there has been limited theoretical focus on how risk perceptions may mediate the social acceptance process, and very few studies have attempted to identify individual characteristics linked to public acceptance of alternative water sources [23
], or beliefs affecting (non) acceptance [24
] in the agriculture sector. This is partially because the assessment of whether individuals are keen to accept a technology represents a relatively recent question [6
], and this calls for a better understanding of the factors leading to positive or negative perceptions on the part of farmers [25
Against this background, this paper seeks to shed additional light on factors explaining farmers’ acceptance of treated wastewater reuse for irrigated agriculture, and how greater acceptance of wastewater uses might be fostered. This is accomplished by using micro-level information collected through a survey on opinion variables and beliefs, as well as individual and farm characteristics, which are used as potential drivers explaining attitudes towards the use of treated wastewater for irrigation. Specifically, we assess risk perceptions towards the reuse of wastewater for irrigated agriculture. Moreover, given that risks appear more acceptable when advantages are better understood [26
], in addition to analysing negative thoughts and feelings concerning perceived risk, a positive attitude dimension is accounted for by looking at perceived benefits/advantages.
The case study concerns a sewage treatment plant located in Emilia-Romagna—an Italian region with a strong agricultural vocation—the water of which could be used by a well identified group of farms in adjacent areas. Primary data were collected using a structured questionnaire and elaborated by means of a classification tree analysis.
The contribution of the paper is mainly empirical as it provides new evidence on the topic. In this sense, it helps bridge the knowledge gap on what predicts acceptance behaviour and allows water planners and utilities to address the actual concerns held by particular communities of farmers. To the best knowledge of the authors, this is also the first time the classification tree approach has been tested in this field of research. The results make a contribution to the literature on the social and attitudinal dimensions of recycled water management and also add, more broadly, to the study of environmental management.
After describing the study area (Section 2.1
) and providing insights on major contributions from the literature on public acceptance of wastewater technology and use of reclaimed water (Section 2.2
), the method is described (Section 2.3
). The results are presented in Section 3
. Section 4
discusses results, while Section 5
provides a conclusion.
The overall results of this paper reveal the existence of a more pronounced perception of benefits rather than risks from wastewater reuse in agriculture among farmers in the case study area. In accordance with the literature [23
], this leads to more positive perceptions on wastewater, favouring higher acceptance levels. From a different perspective, the results also seem to report that a greater openness towards recycled water is linked to a lower perception of risk [32
], rather than the identification of benefits.
The CHAID analysis shows that different variables contribute to explain the different positions on risks and benefits. Table 3
summarizes the partitioning variables and output of the CHAID analysis: explanatory variables are depicted in rows and response variables in columns. Within the table, we report the hierarchic level of the splitting nodes resulting for each explanatory variable, for every tree. The higher the ranking (position identified by a lower number), the greater the explanatory power of one variable in explaining the response variable.
The results corroborate the primary relevance of the perceptions about water quality as a factor influencing the acceptance of recycled water [30
]. However, this applies to the perception of risks only. The wastewater treatment can be seen as a technology that enhances the quality of water, compared to the status quo, despite the fact that, in our case, information about this topic seems to be positively related to higher perception of risks.
As for socio-demographic variables, we are in line with the stream of research reporting an inverse relationship between risk perception and levels of education [23
]. We are also able to endorse the notion that higher information and knowledge (e.g., about the project) increase openness towards adopting the innovation, by increasing acceptance levels [32
]. In the context of our study, this outcome can be related to both perceived greater benefits and perceived lower risk. A possible reason is that, even in the case in which knowledge does not emerge as a factor directly influencing people’s decisions, the provision and availability of information can be seen as an intervening factor engendering trust, which in turn contributes to acceptability [26
Additional drivers explaining the recognition of advantages are cropping choices, neutral expectations on impacts, and low adaptation requirements of current water management practices. In particular, growing alfalfa is the stronger factor explaining the perception of no risk, which can be easily associated with the fact that this crop is not directly used for human consumption. Growers of processed tomatoes have claimed to require water beyond the irrigation season. This could justify producers’ inclination towards the recognition of advantages from the use of a complementary water source, which would fill this gap. On the other hand, in the case of land allocated to grapes, gardens/parks, and permanent pasture, the lack of recognition of specific advantages may be connected to both the lower importance of irrigation for these crops and the lack of interaction between irrigation water and production aimed at human consumption. However, it must be noted that, except for alfalfa, cropping choices are captured by intermediate-to-final nodes of the classification trees, i.e., represent partitioning variables with lower explanatory power compared to other factors located in upper nodes.
Finally, greater advantages are perceived by those believing that local farms would accept the innovation, confirming Siegrist and Cvetkovich’s [26
] assertion that people tend to conform with others’ behaviour. Therefore, the extent to which consequences are accepted may depend on the knowledge that others will eventually be subject to the same effects or that acceptance prevails among the local community.
This paper is subject to at least two limitations. The first concerns the size of the sample (though representative of almost the whole population of the case study) and the emphasis on a narrowly defined area. However, this latter limit could, at the same time, be seen as a strength of our work. Focusing on a well-identified case study, our approach and results are suitable to identify concrete reactions by actors, while taking real life decisions precisely on the use of water.
A second limitation could be the number and type of variables considered, in particular the fact that we decided to leave aside aspects such as wastewater regulation and economic aspects such as the redistribution of treatment costs and water price. The reason lies in that these aspects are traditionally considered more by the economic literature than in the context of social acceptance, accounting for more subjective and hard-to-track elements related to beliefs and perceptions [15
]. On the other hand, water price for farmers in the area is almost negligible, so that relative changes in this variable are not expected to strongly drive farm choices.
Additionally, according to the current law, the burden of the investment cost for water reuse (tertiary treatment) is not charged to farmers; rather, it is paid by households. Therefore, the fact that farmers can currently benefit from a ‘free lunch’, besides contributing to explain their openness towards WWT technology, also made the question of costs rather irrelevant. Similarly, in the study area, water competition amongst different uses is limited. The freshwater used in urban centres is derived from the aquifer, while irrigation water comes from the Po River, which usually brings enough water, except in exceptionally dry years. As a result, farmers in the area are not vitally afraid of water scarcity conditions, even though climate change is hinting at the possibility that things will quickly worsen in the near future. This also hints at a rather low resource cost (in the meaning of WFD) of water. As a result of the above, it is reasonable that farmers neither have special economic motivations to be against water reuse, nor do they expect major economic benefits that would push them to be strongly in favour.
The picture would likely be different if the WWT technology was implemented in other parts of the region, where water scarcity is more relevant, or under future climate conditions, due to the expected increase in frequency and intensity of seasonal water shortages or droughts due to climate change. In these cases, a much higher marginal value for treated wastewater would make it more appealing to dispose of additional alternative sources, which may be expected to positively affect public acceptance [23
] and justify greater investments in WWTP.
Using micro-level information, this study performed an evaluation of the perceptions about benefits and risks associated with treated wastewater reuse for irrigated agriculture, focusing attention on opinion variables and beliefs, as well as farmer and farm characteristics, as potential factors explaining farmers’ opinions.
The results show that drivers of risk/benefit perception are linked, amongst other aspects, with information-related variables (level of knowledge about the water reuse scheme and information available to users). Our results also show the relationship between technical aspects and farmers’ opinions: the type of crops cultivated and the burden to adapt current technologies to use treated wastewater are found to be related to perceptions, though the full understanding of the related causal mechanisms is beyond the scope of this paper.
In terms of policy implications, this confirms the importance of raising stakeholders’ awareness and encouraging their involvement to leverage public acceptance to foster technology diffusion. However, raising the public’s knowledge of water reuse alone could prove to be insufficient to ensure acceptance. Policy measures aimed at informing local actors should look more carefully at local water needs by potential users, build on personal experiences, and address business-specific water-related concerns. This should build on a more thorough assessment of how farms and crops can benefit the most from water reuse. The specific case of farm specialised in feed crops or needing water outside the season in which irrigation water is normally delivered can represent an important basis to build consensus about water reuse. It should also be acknowledged that, in some cases, firms may have good reasons for having no special preferences. In such cases, information about others’ views may in fact affect individual opinion. Transparency in information may be relevant in particular in cases in which doubts can be raised with respect to technical aspects of reusing purified wastewater. Also, an appropriate approach may potentially help increasing trust over time and reduce people’s concerns about risk, while simultaneously acknowledging better potential benefits.
This mix of approaches, focusing the needs of potential users, needs to be contextualised in a shared vision of global and long-term challenges associated with water scarcity, in particular facing climate change.
In the context of Integrated Water Management, these results may inform the decision making process on how to better target efforts to increase acceptance levels. This in turn may support the implementation of the EU 60/2000 Water Framework Directive and favour the competitiveness of the local water industry.
Further research through micro-level investigations should be carried out to more systematically map target variables affecting public acceptance across Europe. This would allow for the development of a knowledge base for the water reuse sector in Europe, especially in more water-scarce regions where the value added of this option is higher. Finally, these insights integrate and do not substitute incentive considerations related to prices, policies, and costs. These remain key drivers, especially in a business environment. The interplay between value proposition, the social dimension of acceptability, profitability, and the role of regulation will be a strategic topic for further research.