The latest weapon in Cape Town's water-saving arsenal is a map that exposes private meter readings to public scrutiny. The initiative has been launched as the South African city enters the third year of its worst drought on record. Unless residents can cut their daily water use to 50 litres per person, city authorities estimate that the taps will run dry on 21 April 2018.
The "City Water Map" has just been launched in an attempt to make a dent in the 200,000 homes allegedly going over the limit imposed by the city on usage. That's 87 litres per person per day for a family of four. This limit was tightened to 50 litres a day after publication of this story.
The water map's landing page provides a bird's-eye view of the Cape Town municipality as it appears on Google Maps. Zooming in to individual properties reveals the street address and the plot number, as well as the water-usage level. The plots of users who are deemed within the water-restriction limit are marked with a green dot.
The city authorities behind the map have gone to great lengths to design it in a way that highlights those who are sticking to the water restrictions, rather than naming and shaming those who don't. They say the aim is to publicise households that are saving water and to motivate others to do the same. They even dropped an earlier idea that a red dot should appear on plots where restrictions were allegedly being broken.
The map has nevertheless sparked controversy. Notwithstanding the mayor's positive rhetoric to "paint the town green", some members of the public are seeing red. Arguments against it include that it's a violation of privacy, that it's divisive, and that it could promote the harassment of properties.
The map applies a theory developed by the University of California in 2015 that households will drastically reduce their water use when they realise they are the odd one out in a water-saving neighbourhood. Cape Town seems to be one of the first municipalities to actually apply the theory.
The water map renders homes publicly accountable for their water use.
How the map works – or doesn't
Properties are marked by a colour-coded dot. A dark green dot indicates properties with a meter reading of fewer than 6,000 litres in the previous month. A light green dot indicates properties with meter readings over 6,000 litres but below the limit of 10,500 litres in the previous month.
There are also grey dots with dark or light green centres. The dark centres are for water usage that's estimated to be 6,000 litres. Light green centres are 10,500 litres.
Pure grey dots apply to properties where the meter read zero in the past month, or for which no meter reading exists. Some properties aren't assigned a dot. These include properties over the limit, as well as properties that are not included in this version of the map, such as commercial and industrial properties and flats.
However, since all these amounts are based on the assumption of a four-person household on each property, and the city has no reliable data on how many people are actually residing at each property, the map is statistically meaningless and quite possible dangerously divisive, many believe.
The fact that the map can give no per-capita breakdown of water usage leaves many doubting the city's official figures regarding the water crisis – without a pinpoint breakdown of the number of people on each property, how can Cape Town officials confidently claim that "60 percent" of Capetonians are ignoring water restrictions?
Unfair targeting
The strength of the water map is its potential to apply social pressure to encourage water savings. Social pressure exerts a powerful influence and shapes behaviour. By allowing the public gaze to fall on every residential property in the municipality, the water map renders homes publicly accountable for their water use.
And rightly so, as water saving is a combined effort. Without this accountability, a common resource such as water is vulnerable to exploitation by a few, at the cost of the whole.
But there is a danger to this strategy. Strong social norms promoting certain behaviour can fragment society, creating a sense of "us" and "them". In this case, "water savers" may stigmatise perceived "water wasters". This would break down the cohesion that's needed for citywide water saving.
Patricia de Lille, the mayor of Cape Town, is clearly aware of this potential pitfall. As she explained, high consumers are often unaware of their consumption, but are willing to change their behaviour once approached.
During this crisis, we all need to work together, not alienate each other.
She added that the intention was to make the map as green as possible‚ and so encourage compliance with the water restrictions. She also added a clarification: properties may have legitimate reasons for exceeding the usage limit.
The Water Map FAQs also urge people not to shame others, saying, "During this crisis, we all need to work together, not alienate each other".
Naming and shaming
Despite these explanations, many members of the public still see the water map as a "name and shame" campaign.
Naming-and-shaming has been used in other save-water campaigns. Sydney, Australia named water-wasters in the local news as part of its 2006-2009 Target 140 campaign.
Cape Town has already applied this strategy. The city has published images of water wasters, as well as the street names of the top 100 water wasters.
The purpose of the water map is clearly not to name and shame. If anything, it seems that the map is a "name and acclaim" campaign; a broadscale representation of all homes showing exemplary savings in the city, meant to act as an incentive to others.
This piece originally featured in The Conversation and can be viewed here. It has been revised and adapted by HuffPost.