What the Cape Town water crisis can teach us about applying behavioural science

David Perrott
Mar 13, 2018 · 12 min read

On Wednesday, the 7th of March, it was announced that Cape Town will not run out of water this year. This comes as a relief to both the leaders of the city and local citizens who have been gearing for life with dry taps and the possibility of commuting to designated water collection points on a daily basis.

The reasons that this nightmare scenario has been taken off the table are tenfold. Some of the key factors include a transfer of agricultural water supplies, new water augmentation systems coming online, a healthy amount of late summer rainfall, and, importantly, a massive shift in the way local citizens consume water.

It has been estimated that citizen water consumption has dropped by close to 100 millions litres per day over the past six weeks. This drop is from 610 million litres in mid-January 2018 to 513 million litres per day during the past week. This is an impressive decrease of around 300 full swimming pools of water per day.

Image from https://coct.co/water-dashboard/

However, this effort did not just happen on its own. It was the product of various campaigns, on-the-ground initiatives, and smart interventions. In taking a closer look at what worked and what did not, we can understand how to improve our efforts in years to come.

Additionally, the water crisis provided a unique learning opportunity to understand how large scale behavioural change can work more broadly. In other words, by using a behavioural lens to look at the events of the last two months, it becomes possible to synthesise take outs that may be useful to other practitioners around the world who are working on urgent behavioural change initiatives from financial independence and physical health to recycling and energy usage.

What worked well:

The Day Zero Campaign:

‘Day Zero’ has become so interwoven into Capetonian vocabulary that it is easy to forget that the concept was actually the brainchild of a cleverly constructed campaign that had to be deliberately thought through, planned out, and operationalised.

In short, the campaign created clear and easy to understand targets for South Africans to work towards. It also helped to make the consequences of running dry more vivid and visceral. This encouraged people to form stronger beliefs about the possibility of not having water, and in doing so, increased the public’s motivation to act.

Other key components of the campaign:

  1. The phrase ‘Day Zero’ worked extremely well as a meme. It is unique, simple, and slightly daunting which allowed it to stand out above the noise of social media. It also prompts curiosity and questioning which works as a nice trigger for conversation and education on the consequences (for example, “what happens at Day Zero?”). Furthermore, the frequent revision of the ‘Day Zero’ date allowed the concept to remain fresh and stay top of mind.
  2. The campaign acted as the foundation where more specific goals and targets could become meaningful and salient. This meant that communications could move from high level general societal mission statements (avoid Day Zero) to specific goals that an individual could aim to achieve on a daily basis.

‘In order to avoid Day Zero, we need to reach a target of 450 million litres of water a day. That means every citizen should aim to use 50L a day.’

3. Lastly, the campaign did not only paint a vivid picture of the problem, but also shared easily actional solutions which allowed for the energy created by high level campaign messaging to be focused in constructive directions.

Behavioural takeouts for practitioners: Ensure that the primary message you are trying to communicate is salient, thought-provoking and in its simplest possible form. This increases the likelihood of shareability and stimulates healthy conversation, which allows for social learning to take place between citizens.

Water collection management at the Cape Town springs

Although this was not the case until recently, in the last month the organisation and management of active water collection points, like the Newlands spring, have worked efficiently. This has lowered collection turnaround time, the occurrence of conflict, and the previous hassles of moving water, by, for example, allowing trolleys for water transportation to vehicles, and more stringent security.

Behavioural take out for practitioners: One of the most important learnings from behavioural science is that big changes can be created by simply making the ideal behaviour slightly easier to do. It is just as important to remove barriers and hurdles to performing particular activities as it is to create awareness and strong motivation.

Social learning through trusted influencers

There were some great initiatives by local influences. Some examples include the head of the DA, Mmusi Maimane’s, continuous push on social media sites like Twitter and Helen Zille’s decision to disclose how much water she was using on a daily basis. There were also large awareness initiatives targeting schools by activists like Catherine Constatinides and organisations like Plant the Seed.

Behavioural takeout for practitioners: The messenger is as influential as the message. Trusted messengers, who have influence and authority within citizen’s social networks, allow for key ideas to be attended to and taken seriously, which increases the likelihood that they will be acted on. This effect will be amplified if the messenger has similar demographics and behavioural features to the citizen group in question.

Group collaboration

In addition, initiatives run by local influencers,committees and groups have been setup, both online and offline, to disseminate important information, share best water saving practices, and discuss new approaches.

These collaborations happened locally on online groups like the Facebook community named ‘Water Shedding Western Cape’. They also happened globally. An example of this was an initiative I set up with Kelly Peters, the founder of BEworks based in Canada. Together we launched an online initiative to crowdsource behavioural tactics from researchers and practitioners around the world. The working output being a publicly accessible Google document that Gravity could leverage and disseminate to other local practitioners and key city stakeholders.

Behavioural takeout for practitioners: Interventions do not have to be initiated by a central authority (government or city). In fact, on-the-ground initiatives can sometimes be more effective due to the individuals’ detailed understanding of the local nuances, and their ability to easily implement, and adjust in response to change. The role of central authorities should be to provide the necessary space, resources, and expertise in order for these collaborations to have a real impact.

What could be improved on:

Management of second-order effects

The worst outcome of the water crisis has been avoided for the time being, but the narrowing of our attention may have pushed previously held values and activities to the periphery. An important example is the dramatic increase in the consumption of plastic bottled water. The less immediate implications of over-using plastic (without efficient recycling systems in place) quickly took a back seat to the more urgent and salient water issue. Now that the blinkers have come off, we are able to get our heads up and the implications of this behaviour are becoming apparent.

A rapid increase in consumption of plastic bottles is one example of a negative second-order effect, but I am sure that there are many others. If you can think of any others, I have started a Twitter thread to discuss them.

Behavioural takeout for practitioners: Although it is difficult, practitioners need to pay close attention to the potential negative externalities and not just the primary behaviour that they are trying to change. Prioritise the interventions that have the greatest impact on solving a particular problem without creating adverse knock-on effects in the process. To help with this, a pre-mortem could be conducted during the initial stages of a project.

Unintentional applications of negative social proof

In many ways, the messages communicated by the city and local government were extremely effective. This included the consistency and frequency across multiple channels, the use of influencers, and the vivid and concrete visualisations of different citizen solutions. One obvious way to improve, however, would be to avoid making what Robert Cialdini and others have coined ‘the big mistake’.

The big mistake is made when, in attempt to change behaviour, the amount of people who are behaving incorrectly is communicated with the intention to showcase the size and urgency of a particular problem. On the surface, this seems perfectly reasonable. Unfortunately, behavioural scientists have shown that we often tend value signals of descriptive norms above logic and reason. In this case, messages like “50% of Capetonians are still not saving water” only work to signal to readers that this is the norm, and in addition, frustrates those who are working hard to save.


Fortunately, this was realised and, in recent weeks, there has been a clear intention to avoid ‘the big mistake’ and take advantage of social benchmarks that align with the desired behaviour.


Behavioural takeout for practitioners: Just like you would do a copy check before releasing a blog post, messages should be scrutinised for the unintentional descriptive social norms that they may communicate. In cases where the majority is performing the undesired behaviour, injunctive norms or testimonials from key local influencers should be used.

Impressions of simple statistical stories

The use of statistics to build meaningful narratives is an important and effective approach to storytelling. However, statistics that are factually true, but give a false impression, can lead to serious backfire effects that risk damaging the credibility and trustworthiness of the messenger, which would make future communications less effective.

One recent example is a narrative that has developed around the average daily usage of Cape Town citizens in comparison to other drought stricken areas such as Melbourne, California, and Sao Paulo at the height of their crises. When compared, these statistics paint a picture of Capetonians as incredible outperformers. This may have some positive implications and be useful in creating in-group comradery. However, what it does not show is that a major reason for this contrast is due to the fact that many South Africans live in informal settlements and use well below 50 litres on daily basis, which significantly brings down the average.

Behavioural takeout for practitioners: Messages that are factually true, but imply something else, may be safe from a legal risk perspective, but could still damage citizen trustworthiness towards the particular messengers. As mentioned earlier, the trustworthiness of messengers is pivotal for the successful dissemination of key ideas, and so should be safeguarded at all costs.

Citizen usage feedback systems

One of the cornerstones of effective behavioural change is providing people with frequent and meaningful feedback that exposes the causal relationship between their actions (e.g less toilet flushes) and their goals (e.g. lower daily/weekly household water usage).

Cape Town has shown that behaviour change can take place with these systems in place, for example, by creating and communicating proxies (one flush = 10 litres) and then prompting people to perform certain activities less frequently or more frequently.

This does not mean we should avoid looking at meaningful feedback systems. Just like electricity and money, it should be easy to track how water is being used, and the difference certain activities can make. In this way, we can create an intimate understanding of household water usage, and work towards better conservation because of it.

Even though easy-to-use water feedback systems are likely have an impact on their own, their real potential is the foundation they create for the kinds of behavioural interventions that would not be possible without them. Some possible interventions include daily or weekly goal-setting, progress visibility, neighbourhood benchmarks, and comparisons to ‘households like yours’.

Fortunately, there are already a few active projects in this space. Drop Drop and Dropular to name a few. ‘Drop Drop’ for example is a product under development by UCT’s iCOMMS team. The product is a mobile application that allows users to access their daily water usage, predicted end-of-month water bill, and water saving tips. This is an early example of the role that technology can play in creating meaningful feedback systems that help citizens change their water usage behaviour.


Behavioural takeouts for practitioners: Providing people with tight digital feedback loops allows them to build a more intimate understanding of the effects that their everyday activities have on the world around them. Feedback loops also open the door for a host of other proven interventions that are difficult to implement without them. These interventions include goal assignment, progress visibility and social benchmarking.

Putting our learnings into practice

Gravity took on several different behaviourally-focused initiatives in an attempt to improve Cape Town’s situation. The initiative that seems to have the most potential going forward was a pilot project that we launched towards the end of January. I have briefly shared the details below.

Working with the noisy nudgers

One of the biggest problems we identified during the water crisis was an idea-adoption gap. There were many brilliant solutions, water saving actions, and techniques that were being shared over radio and social media. The challenge with this was to actually get citizens to adopt these solutions and incorporate them into their daily routines so they could become consistent habits. For example, using grey water from your shower to flush your toilet is a simple and impactful solution, yet performing this task on a daily basis requires it to be top of mind, planned for, and prompt enough motivation to be carried out. In other words, it is the epitome of the saying ‘easier said than done’.

With this in mind, our intention was to explore the ways in which we could share conservation messages to households (where the targeted behaviours actually take place), by means of a meaningful and trustworthy medium, that could also keep those messages top of mind.

We realised that an effective way to achieve this was by working with pupils in local primary schools. Suburban households are an important subset where the largest citizen behaviour change needs to take place, and what better messenger to nudge household members in the right direction than the children that live with them.

We also realised that an instructive approach, which would involve just lecturing pupils about the problem and its solutions, would only proliferate the idea-adoption gap mentioned earlier. To avoid this, we developed a fun and engaging design-thinking-style workshop, where the water crisis was positioned to pupils and they had to collaborate in teams to generate approaches that could be actively implemented within their households. This thinking was inspired by well-known behavioural theories such as the Ikea Effect. According to this theory, the workshop style, that encouraged pupils to work towards creating their own ideas, meant that they would then take more ownership of these ideas and perceive these ideas to be of of high value, which would later encourage adoption.

In addition to this, we asked the pupils to choose their three favourite water saving ideas, that is, the actions that they would like to implement immediately (as soon as they got home from school). The pupils then wrote these actions as statements on a commitment card and teamed up with a commitment buddy who signed their cards and were prompted to check-in on a weekly basis.

Later, the teacher took photos of all the pupils holding their cards, printed them and stuck them up in the classrooms as a continuous reminder of the water saving actions that they had committed to.

Finally, we open-sourced the workshop content so that the teachers could use it without us. Certain pupils were selected from the grade seven classes (student leaders at the schools) and trained to facilitate the workshop. They then facilitated the design-thinking workshop with small groups from younger grades. This allowed for a kind of scalability that we would never have been able to achieve if we had control of the content and tried to conduct the workshops in our own capacity.

Looking ahead

There is much that the country, and the world, can learn from the Cape Town Water Crisis. Its successes and failures have created a useful space for behavioural researchers and practitioners who may have to face similar challenges in the future. My hope is that the learnings discussed in this article can will contribute towards this.

If you would like comment on the ideas discussed here, you can connect with me on Twitter @DavidPerrott or via email with david@gravitideas.com

David Perrott

Written by

My writing revolves around behavioural science, technology, philosophy and design. Founding Director @gravityideas

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