Against the backdrop of climate change and dwindling water resources, supplying water to large metropolitan areas is becoming an increasingly challenging task for public authorities, who must find urgent solutions. One of the clearest and most viable ways forward is to incorporate recycled tap water into urban supply systems. However, despite being sustainable and safe, this option faces a major obstacle: consumers' instinctive, psychological resistance. Now, an international study led by the Universitat Oberta de Catalunya (UOC) has identified a method that could prove key to overcoming resistance: influencer marketing.

Research led by Professor Inma Rodríguez-Ardura, coordinator of the UOC's Digital Business Research Group (DigiBiz), found that influencers on platforms such as Instagram use sensory and emotional content to build mental images, and that this is more effective than purely rational arguments for overcoming resistance to drinking recycled tap water and encouraging sustainable consumption. Recycled tap water is not consumed directly, but is fed back into supply systems, where it is mixed with water from other sources and subjected to the treatment processes required for human ingestion. The study, published in the British Food Journal, is based on the experience of 800 Instagram users from Barcelona and Phoenix. The authors also include Professor Antoni Meseguer-Artola and Gisela Ammetller, fellow members of the UOC's Faculty of Economics and Business.

The research team understood that, while there is a real and urgent need to encourage the consumption of recycled tap water in areas threatened by the climate emergency, the main obstacle to uptake is not its safety, but how it is perceived. Although recycled tap water is safe for human consumption if it has gone through appropriate water treatment systems, when people know that the source is treated and purified waste water, for many their instinctive reactions include rejection, fear and even revulsion. This visceral reaction is compounded by a widespread tendency among consumers to undervalue the supply of tap water, or take it for granted until a supply crisis occurs.

In this context, traditional communication strategies, based predominantly on technical data, scientific presentations and rational arguments about collective savings, are demonstrably insufficient for changing deeply ingrained habits. "Although sustainable water consumption objectively benefits society as a whole in the long term, just communicating this idea is not enough to get consumers' full engagement," said Rodríguez-Ardura. This is where influencer marketing comes in. According to the research, this tool helps make abstract benefits like sustainability more tangible, linking them to positive emotions and feelings, aspects that public institutions and supply companies have failed to exploit to date.


The power of mental imagery

The study centres on the concept of mental imagery and how social media, specifically Instagram, can be used to evoke it. The researchers set out to determine how the content created by influencers can generate subjective, transformative and compelling experiences for their followers. Rodríguez-Ardura, who is affiliated to the UOC-DIGIT research centre, explained the importance of this psychological mechanism: "Mental imagery is a subjective experience that involves conjuring up vivid feelings, objects, people or events, even if they did not happen or are not real. It's a type of feeling we create in our minds that makes things that were perceived as abstract, complex or distant seem tangible, understandable and real."

The research identifies two dimensions within this phenomenon: elaborated imagery, which the consumer creates voluntarily through cognitive effort (such as calculating how much plastic is saved by drinking tap water), and spontaneous imagery, which arises effortlessly or unconsciously, prompted by a stimulus. For example, a video of an influencer drinking recycled tap water out in the sunshine might automatically evoke mental images of it being refreshing and thirst-quenching, without the need for complex rational processing.

One of the key findings of the study, conducted on a sample of 800 Instagram users between the ages of 18 and 54, is the asymmetric impact of different types of message. Although informativeness is important for the formation of mental images, hedonic or sensorial content has a significantly greater impact. "To break down the barriers to sustainable water consumption, it's not enough to get people to understand that tap water is healthy and safe. It's also vital to recreate the experience of drinking it as something desirable, refreshing and emotionally satisfying," said Rodríguez-Ardura.

The study also explores the concept of "transportation", a psychological state of deep immersion in a narrative. The data reveals that mental imagery acts as a powerful antecedent or trigger for this phenomenon, leading the consumer to become so absorbed in the influencer's story that they lose track of time and feel part of the scene before them on the screen. Facilitating this vicarious experience reduces the capacity for critical thinking and opposition to the message. It fosters an enduring emotional connection that is key to transforming attitudes on sensitive issues, allowing us to experience the benefits of recycled tap water and its sustainable use before we actually taste it.


Implications for the future of public campaigns

The study's conclusions offer a clear roadmap for public institutions and bodies responsible for water management. It suggests that campaigns should not be limited to providing information, but should strive as much, if not more, to have hedonic and sensory appeal. If an authority wants to encourage the use of recycled tap water, its strategy should focus on helping the public to visualize and feel its positive properties.

"A public institution that promotes the use of recycled tap water in the urban supply system must focus its strategy on helping consumers to vicariously 'visualize' and 'feel' the positive properties of the water. This can be achieved, for example, through influencer marketing initiatives focusing on conveying the sensation of drinking, the freshness of the water, or doing healthy activities where drinking water is an emotionally desirable experience," said Rodríguez-Ardura.


A model applicable to other social challenges

These results have opened up new lines of research for the UOC team. They are now studying the impact of factors such as the authenticity and credibility of the influencer, the extent to which the audience identifies with the influencer, or whether messages are informative or hedonic. This communicative approach can be applied to other areas beyond water. The researchers point out that using mental imagery and transportation to persuade can be extended to other scenarios where there is resistance, fear or concern about health. "Scenarios where this new technique could be applied include campaigns to encourage people to vaccinate or recycle, or to combat climate change, as the key in all these cases lies in making an abstract benefit tangible through a positive sensory experience," they explained.


This project is aligned with the UOC's Digital transition and sustainability mission and contributes to the UN Sustainable Development Goals (SDGs) 6, Clean water and sanitation; and 12, Responsible consumption and production.


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