Spillovers

First, the importance of unintended consequences. It is not enough for interventions to only address the behavioural biases driving excessive household and personal water consumption – researchers and policymakers should also consider the possibility of unintended, secondary effects of their interventions.

A recent study by Leong et al. [5] on water use behaviours among 385 Singaporean households illustrates this point. Consistent with past literature, the findings demonstrated that providing real-time feedback through smart devices can significantly reduce household shower water use (in this case, by 22% or an average of 5.54L per shower over the treatment period). Importantly, the study also documented evidence of negative spillovers; households with smart shower devices increased water use in other activities by 2.5% per day, though net water use was still reduced by 4.7% (or 23.5L per day).

The latter finding is consistent with the moral licensing theory, which posits that after performing a moral behaviour (conserving water), individuals are more likely to feel entitled to behave immorally in other aspects (using more water for other activities; [6]).

Taken together, these findings underscore the importance of considering the behavioural effects of water policies. Interventions should not only address the root issue (e.g., the lack of feedback on water consumption behaviour) but also consider and pre-emptively address potential behavioural biases (e.g., moral licensing) that can erode water conservation effects.

Prices, private operators and the Devil Shift

Second, more research is needed to better recognise how behavioural biases and heuristics influence public perceptions of water service providers, particularly the persistent antipathy towards private operators. This hostility is sometimes well-founded; but at other times, it persists even when objective economic assessments show positive outcomes [7]. This bias, where individuals exaggerate the negative motives, behaviour, and influence of opposing entities, exemplifies what researchers call the “Devil Shift” [8].

Studying such behavioural biases presents greater methodological challenges as they may not be captured by traditional methods such as surveys and regressions. However, experiments and narrative and discourse analyses tools and method have been used here to great effect. For example, evidence of in-group bias, such as the exaggeration of water suppliers’ unreasonableness and the downplaying of local governments’ responsibility for effective water management, could be elicited through applications of the Q methodology [9] and narrative analysis [10].

Novel science

Finally, a behavioural approach offers valuable insights into factors influencing public acceptance or resistance toward new or controversial water technologies. Such technologies will become more important in future, as the supply of usable fresh water dwindles.

Recycled Drinking Water (RDW) presents a compelling case study: despite being scientifically proven as a safe, cost-effective, energy-efficient, and sustainable solution to global water scarcity [11], it continues to face significant public resistance. Traditional policy approaches that rely on information campaigns to build public trust have largely fallen short, with several notable failures where public opposition led to the abandonment of RDW projects [12–14].

Addressing RDW acceptance through a behavioural lens allows us to address its psychological and emotional barriers to acceptance. Research by Leong and Lebel [15] demonstrates that the “yuck factor” – variously defined as a ‘psychological repugnance’, ‘disgust’, or ‘profound discomfort – significantly limits public acceptance of RDW. Their choice experiment revealed a crucial insight: social conformity per se appears to provide sufficient reason for behavioural change, rather than information or economic incentives. People are more likely to accept or overcome their initial aversion to RDW when they learn that many others have already done so.

Applying a behavioural approach to water policy provides crucial insights into the spectrum of potential outcomes from policy interventions, while recognising how cognitive biases shape what otherwise be dismissed as irrational behaviour. Importantly, this approach also creates new possibilities for increasing public acceptance of new and novel science that can transform the way we live and use the scarce – yet infinitely reusable – of water.