How 5 cities in the USA, Brazil, Australia and South Africa nearly ran dry but got water use under control before Day Zero

Water scarcity is often viewed as an issue for the arid American West, but the U.S. Northeast’s experience in 2024 shows how severe droughts can occur in just about any part of the country.

Cities in the Northeast experienced record-breaking drought conditions in the second half of 2024 after a hot, dry summer in many areas. Wildfires broke out in several states that rarely see them.

By December, much of the region was experiencing moderate to severe drought. Residents in New York City and Boston were asked to reduce their water use, while Philadelphia faced risk to its water supply due to saltwater coming up the Delaware River.

Before the drought, many people in the region weren’t prepared for water shortages or even paying much attention to their water use.

As global temperatures rise, cities throughout the U.S. are more likely to experience hotter, drier conditions like this. Those conditions increase evaporation, drying out vegetation and soil and lowering groundwater tables.

The Northeast drought was easing in much of the region in early 2025, but communities across the U.S. should take note of what happened. They can learn from the experiences of cities that have had to confront major water supply crises – such as Cape Town, South Africa; São Paulo, Brazil; Melbourne, Australia; Las Vegas; and New Orleans – and start planning now to avoid the worst impacts of future droughts.

Lessons from cities that have seen the worst

Our new analysis of these five cities’ experiences provides lessons on how to avoid a water supply crisis or minimize the effects through proactive policies and planning.

Many cities have had to confront major water supply crises in recent years. Perhaps the most well-known example is Cape Town’s “Day Zero.”

After three years of persistent drought in the region, Cape Town officials in fall 2017 began a countdown to Day Zero – the point at which water supplies would likely run so low that water would be turned off in neighborhoods and residents would need to fetch a daily allocation of water at public distribution points. Initially it was forecast to occur in April 2018.

Water rates were raised, and some households installed flow restrictors, which would automatically limit the amount of water that could be used. Public awareness and conservation efforts cut water consumption in half, allowing the city to push back its estimate for when Day Zero would arrive. And when the rains finally came in summer 2018, Day Zero was canceled.

A second example is São Paulo, which similarly experienced a severe drought between 2013 and 2015. The city’s reservoirs were reduced to just 5% of their capacity, and the water utility reduced the pressure in the water system to limit water use by residents.

Water pricing adjustments were used to penalize high water users and reward water conservation, and a citywide campaign sought to increase awareness and encourage conservation. As in Cape Town, the crisis ended with heavy rains in 2016. Significant investments have since been made in upgrading the city’s water distribution infrastructure, preventing leaks and bringing water to the city from other river basins.

Planning ahead can reduce the harm

The experiences of Cape Town and São Paulo – and the other cities in our study – show how water supply crises can affect communities.

When major changes are made to reduce water consumption, they can affect people’s daily lives and pocketbooks. Rapidly designed conservation efforts can have harmful effects on poor and vulnerable communities that may have fewer alternatives in the event of restrictions or shutoffs or lack the ability to pay higher prices for water, forcing tough choices for households between water and other necessities.

Planning ahead allows for more thoughtful policy design.

For example, Las Vegas has been grappling with drought conditions for the past two decades. During that time, the region implemented water-conservation policies that focus on incentivizing and even requiring reduced water consumption.

Since 2023, the Las Vegas Valley Water District has implemented water rates that encourage conservation and can vary with the availability of water supplies during droughts.

In its first year alone, the policy saved 3 billion gallons of water and generated US$31 million in fees that can be used by programs to detect and repair leaks, among other conservation efforts.

A state law now requires businesses and homeowner associations in the Las Vegas Valley to remove their decorative grass by the end of 2026.

Since 2002, per capita water use in Las Vegas has dropped by an impressive 58%.

Solutions and strategies for the future

Most of the cities we studied incorporated a variety of approaches to building water security and drought-proofing their community – from publishing real-time dashboards showing water use and availability in Cape Town to investing in desalination in Melbourne.

But we found the most important changes came from community members committing to and supporting efforts to conserve water and invest in water security, such as reducing lawn watering.

There are also longer-term actions that can help drought-proof a community, such as fixing or replacing water- and energy-intensive fixtures and structures. This includes upgrading home appliances, such as showers, dishwashers and toilets, to be more water efficient and investing in native and drought-tolerant landscaping.

Prioritizing green infrastructure, such as retention ponds and bioswales, that help absorb rain when it does fall and investing in water recycling can also diversify water supplies.