Applauding people publicly for their successful efforts to reduce water use at home may be an effective means of driving water-wise behaviour across a city. This kind of positive messaging by city utility managers can work alongside other methods that are traditionally used to drive demand-side water conservation measures among households, such as water restrictions and tariff increases.
This is what our research team found following a six-month experiment using behavioural “nudges” amongst household water consumers in Cape Town during the drought last summer.
Behavioural nudging is an approach used by behavioural economists: we try simple interventions that are geared towards encouraging people to make better decisions in a context such as, for instance, when a city like Cape Town needs to alleviate its water crisis. City utility departments around the country can use similar approaches to drive positive behaviours in other areas, such as cutting energy use, or waste reduction and recycling. In our experimentation, we tested how positively-framed messages can nudge people to voluntarily take on water conserving behaviours.
The experiment targeted over 400 000 households in Cape Town from December 2015 to April 2016. Working with the city, our team at the environmental policy research unit (EPRU) at the University of Cape Town included a series of positive messages in a randomly selected group’s monthly utility bills. Each home received one of nine differently framed messages that was geared towards changing their water use habits.
Of these messages, the one that consistently produced the greatest water reduction behaviour, was the one which advised people that the names of the top water savers would be published on the city’s website. For this specific intervention, people responded by reducing their water use by 1.9%.
Some of the messages used during the six-month period had a financial thread to them: unpacking the city’s water tariff structure graphically and notifying people about how much money they would save through cutting their water use, or how much it would cost them if they didn’t. Some messages offered water-wise tips. Other messages used social norms, comparing people’s consumption to that of their neighbours, while others tapped into intrinsic values and rallied people together under a “common good” value system by appealing to people to work together as a community to save water for everyone’s benefit.
Messages emphasising the cost of water to users seemed less effective, particularly amongst the higher income groups who don’t feel the pinch when prices get hiked.
The carrot or the stick?
The City of Cape Town has been working closely with EPRU for the past two years in order to find the best evidence-based approaches to managing the municipality’s water supply. This is particularly urgent now. After three years of drought across the region, by the summer of 2017, only about 20% of the water left in Cape Town’s dams is accessible, resulting in extensive water restrictions. A changing climate will make these sorts of droughts and associated water management challenges more commonplace in future.
The city is now gearing up to work with our team in order to test whether a “carrot”’ or “stick” approach is the best way to get households to voluntarily reduce their water use. The “carrot” approach uses the positive messages to nudge behaviour change, as was tested in the first phase of research. Various “stick” approaches are those traditionally used by municipalities to drive behaviour change such as water restrictions, or increasing water tariffs.
Other “stick” approaches used more recently, include naming-and-shaming where, in February, the city published the addresses of the 100 most wasteful water users in the metropole. This was hailed by many concerned citizens as a positive move, showing how effective a “common good” approach to messaging can be. The city also sent private letters, along with people’s utility bills, to households whose water use is greater than 50 kilolitres (kl) a month. The letters highlighted the high water use, and indicated that water restrictive devices would be implemented if households didn’t change their behaviour.
Our EPRU team will soon begin analysing how these different approaches impacted on water use behaviour during this summer, and compare it with our findings from the first phase of the project. The results will be critical for helping to inform the city on the most effective way to encourage voluntary water-wise behaviour.
However, in the analysis of the extent to which water reductions were achieved during the summer of 2017, we will need to take into consideration all of these interventions that are geared towards behaviour change, as well as other technical issues such as a drop in pipe pressure.
Once we have done this analysis, we will work with the City of Cape Town to see how we can integrate these evidence-based findings into their processes and policies.
We also hope that other municipalities around the country will engage in a similar mutual learning process. We will host national workshops where big municipalities will be invited to see how they, too, can incorporated these evidence-based ideas into their policies.
Professor Martine Visser and Dr Kerri Brick are behavioural economists at the University of Cape Town’s environmental policy research unit. Samantha DeMartino is completing her doctoral studies in economics at Sussex University. The research was funded jointly by the South African National Research Foundation, the Norwegian Research Council, and the Water Research Commission.