At the height of Cape Town’s headline-grabbing 2018 drought, the South African climate scientist Piotr Wolski shared a story from an old Kenyan herdsman.

Sometimes, he said, his village would be hit by a cattle-killing drought. Every decade, this would escalate into a goat-killing drought (goats being more durable than cows), and once in a lifetime, the village would suffer a man-killing drought.

And then came this latest devastating long dry. “So is Cape’s drought [a] cattle-, goat- or man-killing one?” Wolski asked.

For four years, from 2015 to 2018, rainfall had reached record breaking lows for South Africa’s “Mother City”. By summer 2017, dam levels were at less than 20 per cent and the army was on standby as the city was declared a national disaster site.

By January 2018, the countdown for the so-called“Day Zero”, when the municipal taps would run dry, was fast approaching.

The fear in Cape Town that this was shaping into a man-killing episode was high.

Cape Town had become a land of beige, dead lawns, two minute showers with a bucket to catch grey water, and expensive bottled water shipped in from Johannesburg as restaurants refused to serve tap water.

The city’s four million residents were limited to 50 litres a day per person, a severe measure that ultimately staved off Day Zero until the rains finally came in winter 2018.

Right now, with drought-ravaged communities across large parts of Australia facing the prospect of their own Day Zero, are there lessons for them in Cape Town’s pain?

The South African city’s experience provides insights into how behaviour change campaigns can rally citizens to overcome dire situations. But it also reveals how even the best efforts can be derailed by politics.

There are enough similarities between the Australian and South African geographic and climate realities to make comparison instructive.

“The physical environment, rain patterns, are quite similar between southern Australia and southern Africa,” says Professor David Karoly, one of Australia’s most eminent climate scientists, and leader of the CSIRO’s Earth Systems and Climate Change Hub. “So having drought there and seeing it is really an example of a similar risk here.”

Australia already has a highly variable climate, he says – as famously documented in Dorothea Mackellar’s iconic homage to this “land of drought and flooding rains”.

As these wild swings in natural variability are overlaid by extremes powered by human-driven climate change, Australian cities will be in big trouble if they don’t manage future dry spells on an infrastructure and human level, says Professor Karoly.

There’s now little doubt about the culprit in the Cape Town emergency.

Scientists have determined that climate change had made the event three times more likely, as past trends gave no indication of what was to come. It was the worst short term drought in the city’s history.

On our side of the planet, findings by Melbourne Water and the CSIRO have stated that Melbourne could be at risk of a water crisis similar to Cape Town’s within the next 10 years.

What ultimately saved Cape Town was a strategy of massive urban behaviour change, underwritten by some innovative psychological methods such as the cleverly pitched – albeit frightening – Day Zero countdown.

These are strategies Australian communities may seriously need to consider as factors like climate change and rapidly growing populations drive up water consumption and the probability of drought.

Cape Town’s water usage per person was just 50L per day per person – way less than the 155 litre limit Melbournians were urged to stick to during the Millennium Drought, or the 129 litre average realised by Brisbane residents through that long dry, when Queensland implemented some of the toughest urban water restrictions in Australia.

Historically, the trend in Melbourne and many Australian cities has been to throw money at droughts rather than implement more stringent water restrictions, says Professor Lee Godden, director of the Centre for Resources, Energy and Environmental Law at the University of Melbourne.

She points back to the controversial decision by the Victorian Government in 2007 to build a $4bn desalination plant at the height of the Millennium Drought.

“That’s why it was the political decision to build the desal plant. It was politically much more palatable to put in a technical solution than to continue with what would be quite unpopular restrictions.”

While the desalination plant means Melbournians may never have to countdown to “Day Zero”, the reality of longer, harsher droughts will have deep financial implications for Australians if governments sticks to this strategy rather than encouraging any change in behaviour around water consumption, says Professor Godden.

In that same vein, the controversial announcement in October by the Federal and NSW Governments about a new dam to relieve the drought has copped criticism for being hugely expensive and, given the long time-frame for construction, providing no relief in the current crisis.

“If you are west of the divide in NSW at the moment your concern isn’t about a dam, your concern is about water today and tomorrow,” said NSW shadow minister for water, Clayton Barr.

But there are other effective ways to manage drought, as the Cape Town experience shows, having used a number of innovative psychological and behavioural measures to slash water consumption.

These included posting updates on the current dam levels on electric signs along freeways, a local bus company whose new branding read “Saving Water One Dirty Bus at a Time”, and even exercising some public shaming by publishing a list of the top 100 residential water users.

One of the most controversial but compelling tactics enlisted as the drought worsened was the publicly available “City Water Map”. This opened up residents’ private meter readings to scrutiny as a Google Maps layout detailed their addresses and daily water usage.

A happy green dot appeared over those households who were saving water, but non-complying households were very obviously left blank.

“Psychological means are effective when socially engineered in the right way,” says Dr David Olivier, a research fellow from the Global Change Institute at the University of the Witwatersrand, Johannesburg.

“For example, it’s far more effective to send the message ‘people in our area save water’, which puts social pressure on people to conform to the area they are in, than to say simply ‘save water’.”

Australia has already had a taste of this kind of social engineering harking back to the “Don’t Be a Wally with Water” television campaign in the late ’80s, a gentle but cleverly crafted campaign enlisting humour to teach lessons in water-wise behaviour.

But when it comes down to a drought crisis like Cape Town’s, it was necessary to create messaging that packed a bit more of a punch, argues Dr Olivier.

The ominous “Day Zero” catchphrase, for example, had an almost instant effect on slashing water use.

“Probably the greatest psychological leverage during the Cape Town drought was the Day Zero countdown – but it was borderline panic-inducing too. So, it’s a fine line,” he says.

These behavioural campaigns ultimately saved the day in Cape Town, despite the fact that the city had been doing the hard yards to plan for a water-safe future over many years.

Despite widespread misconceptions, Cape Town’s water planning had been internationally recognised, including by the C40 Cities Awards, Imperial College London and the American Water Works Association. It’s achievements included reducing water loss from leakages to less than 15 per cent, which is half of the global average (40 per cent) and almost on par with Australia and New Zealand at 10 per cent.

But a schism between the national and provincial governments – represented by the country’s two opposing national parties – meant Cape Town’s plight wasn’t taken seriously by the national government until the city was in the thick of it.

This included a breakdown in water allocation where the national government gave too much water to agriculture, effectively sucking Cape Town’s residential population dry.

It could be argued that similar political fractures are playing out in Australia as New South Wales threatens to walk away from its obligations under the Murray Darling Basin Plan, a central grievance being that too much water is given to the environment ahead of people.

As anger and distress flow through NSW in the absence of water, a full-scale kerfuffle between the federal and state governments is underway over who gets what from the drying Murray-Darling.

It’s a classic farming versus people debate which, as the Cape Town experience suggests, could undermine hard-won agreements around water sharing and allocation.

The vulnerability of even the best laid plans around water to adversarial politics makes behavioural change campaigns all the more imperative, argues Dr Olivier. Such campaigns “remain the only immediate response there is when a water crisis hits, because water augmentation infrastructure takes so long to build.

“The drought is usually over by the time the project comes online. And psychological means remain by far the most economically efficient way to get through a crisis.”