Woman carrying water on her head over parched land

South Asian woman carrying water on her head, 2016 – photo by Gaurav Bhosle

Worldwide Water Shortage: The Glass Really Is Half Empty

The city of Cape Town ran out of water in 2018. The crisis brought more than 4 million people to the brink of having no running water in their homes and businesses. The government announced that on “Day Zero” household taps would be dry and residents would have to line up at communal stations to collect a daily water ration.

people lined up with jugs to get water

Residents waited to collect water from a natural spring in Cape Town. Photo by Discott.

The Cape Town crisis was only averted in part by the arrival of exceptional last-minute rainstorms. The most alarming aspect of the Cape Town water crisis is that it is not unusual. This is not the only major city in the world to experience a drastic shortage of water in recent years. Dozens of cities in Brazil and India for example have experienced similar conditions.

In 2015 Sao Paulo, Brazil’s largest and wealthiest city, was on the verge of limiting water delivery to two days a week. Exceptional rains again helped save this city. More than 20 million people live in the Sao Paulo metropolitan area. In 2013 hospitals in New Delhi cancelled surgeries because they did not have enough water to sterilize instruments. The city of Chennai in India (also known as Madras) relied entirely on water delivered by truck for almost a year. India is home to more than one billion people and is one of the countries most at risk of running out of drinking water. Altogether one quarter of the world lives in areas at high risk of severe water shortage. Water consumption exceeds sustainable limits during at least part of the year in more than half of the world’s river basins.

What has changed so that major cities now face drastic water shortages, even cities that are environmentally aware? Cape Town is one of the world’s most environmentally advanced cities, and in previous years it received international recognition for its water management. There are several obvious factors. World population is now close to 8 billion, and the fastest growing areas also happen to be most at risk for drought. Run-down infrastructure in countries that were the first to industrialize is a major issue – for decades, New York lost at least 20 million gallons a day from leaks in the enormous tunnels that bring water to the city. Watersheds everywhere, critical as clean water sources, have been neglected or destroyed. Most of the great rivers of the world are so polluted that they longer provide untreated water that’s safe to drink.

One quarter of the world lives in areas at high risk of severe water shortage.

And of course human greed can never be discounted. Sanaa, a city of 4 million in Yemen, is one of the oldest continually inhabited cities on Earth and is likely to become the world’s first capital city to completely run out of water. Yemenis use 40 percent of their water to grow qat, a narcotic that’s the country’s largest cash crop. This is far more water than the Yemenites use to grow food. But before judging the foolish Yemenis, understand that it takes 1.5 gallons of water to make 1 plastic bottle. More than 20 billion of these are made and thrown into landfills each year – 500,000 of them in the time it took you to read this paragraph. Perhaps the Yemeni qat farmers are not exceptionally foolish.

The looming water shortage in Yemen could have been avoided, but the 33-year rule of its president Ali Abdullah Saleh was notorious for its corruption and ineptitude. While not nearly the same level as in Sanaa, government incompetence nevertheless is failing to cope with projected shortages in Athens, Bangalore, Cairo, London, Mexico City, and elsewhere. Fourteen of the world’s twenty largest global megacities experience periods of water scarcity every year. Cities in the US threatened with the loss of their drinking water are Los Angeles, Phoenix, El Paso, and Miami. None of these cities are taking steps that will be sufficient to cope with the problem.

“Whiskey is for drinking, water is for fighting over.” – Mark Twain

The crisis in Cape Town came dangerously close to armed conflict. Conspiracy theories, boosted by social media, were rampant. It was claimed that there was no real shortage, that the crisis was a scheme to benefit water treatment companies based in Israel. And as is common throughout the world, the hardship was not shared equally by all citizens. Wealthier neighborhoods are located where water is more abundant. Open conflict seemed imminent, and the government was on the verge of calling in troops before the crisis was averted. The same tensions were felt during the crisis in Brazil.

Solutions to the decrease in water sources are entirely possible, but only if all involved decide to cooperate.

The most at-risk countries are in politically unstable regions. It is easy for people believe that foreigners are taking advantage of them, and especially easy to think so when politicians fan these fears for personal gain. Pakistan and India, for example, share many of the same water sources, sources that are facing catastrophic shortages. These nations are bitter enemies who possess nuclear weapons. Wealthy areas have shown an impressive ability to seize water from other regions, leaving their victims in a condition of scarcity. Solutions to the decrease in water sources are entirely possible, but only if all involved decide to cooperate.

Unlike many of the global problems we face today, the solutions to the shortage of drinking water are clear. Agriculture consumes by far most of the fresh water in the world, perhaps 80%, so this is the place to start. The problems of agricultural water use are readily seen in the Central Valley of California, the most fertile agricultural region in the world. It has the largest amount of the highest-grade soil, the sun shines there about 300 days a year, and the climate is conducive to growing more than 230 different crops. The problem is that doesn’t rain in the Central Valley for half the year, not at all, and water for the crops must be brought from melting snow in the Sierra Nevada mountain range that rises to the east.

Growing Food in the Desert

California in recent years has experienced historical levels of drought, and a great deal of attention has been paid to water conservation. Attention yes, but not necessarily solutions. Many of the farms, vineyards and orchards of the Central Valley irrigate their crops the same way that Sumerians did 7000 years ago. Farmers flood their fields and lose much of the water to evaporation. For other crops, giant sprayers shoot water into the air to fall like rain on days that are sunny, hot, and dry. The result in even more evaporation loss. It’s not just the way that water is used, it is what it is used it to grow. Almost all of the world’s crop of almonds comes from the Central Valley, and almonds are California’s most profitable crop. But it takes one gallon of water to grow one single almond.

Farming is a business, more so in California than most other places, and growing almonds is very profitable. Large corporations now control most agricultural enterprise in California and make use of government-subsidized water rights that were established long ago for family farms. They pay much less than the true cost of the water delivered to them. Residential customers pay ten times or more for water than what farmers pay – in some places much more. These subsidies cost the government many millions of dollars a year and make it cheaper for these farms to squander great quantities of water than it would cost them to conserve it.

Almonds are not the only high-water use crop grown in California. Rice is grown in large flooded fields (“rice paddies”), and alfalfa uses the most water of all – more than twice as much as either rice or almonds. Alfalfa is grown as a feed crop for cows. When water and water-intensive crops are used to grow dairy and meat, the water budget multiplies exponentially. Delivering one pound of beef to the dinner table requires as much as 1,800 gallons of water. California has more dairy cows than any other state, and it takes about 1,000 gallons of water to produce one gallon of milk.

It takes one gallon of water to grow one single almond.

Since climate change will reduce the snowpack in the Sierras by one third or more, changes to agriculture in the Central Valley are inevitable. But change in water infrastructure threatens the profit of those who use lots of water. Legal rights to water are grounded in practices from 150 years ago and long established in court. There are technical challenges to improving water use as well – for example, replacing flood irrigation with drip irrigation could cut water loss by 50%, but widely used mechanized harvesting can damage the drip equipment, and rodents frequently chew through the drip lines to get to the water inside.

Water, Hard and Soft

Drip irrigation is expensive to install, and California agribusiness instead lobbies for the state to pay for new water infrastructure. Massive dams, aqueducts, and centralized treatment plants dominated 20th-century water planning. This infrastructure was responsible for one of the most important developments in human history. A little over 100 years ago these management systems greatly reduced water-related diseases. Previously cholera, dysentery, and typhoid fever claimed millions of lives each year, especially those of children. In the decades just before and after 1900, more than 20 million people in India alone died of cholera.

Graph showing the reduction in deaths from diarrhea from 1900 to 1960
Will this trend reverse? Transitions to freshwater sustainability, Peter H. Gleick. Proceedings of the National Academy of Sciences Sep 2018, 115 (36) 8863-8871

This “hard path” to water management brought tremendous benefits to billions of people around the world by protecting health, expanding hydroelectricity, irrigating farmland, and controlling floods. But the hard path also had costs. Tens of millions of people lost their homes. The flow of most of the world’s major rivers is now a trickle by the time it reaches their delta outlets, damaging fisheries and drying up this critically important habitat. More than one quarter of freshwater fish species are now threatened with extinction. Virtually all of the major rivers in the US are dammed, and new sources of natural fresh water are limited. And paradoxically, enormous quantities of water are lost to evaporation from the reservoirs created behind the dams.

Natural soft-path water management methods include replenishing aquifers … and restoring watersheds that both act as reservoirs and as the best cleaning systems for recycling groundwater.

For these reasons and more, hydrologists now advocate a “soft path” to meet the growing need for water. In fact, water usage in industrialized nations appears to be following the “Kuznets curve” – a speculative idea that says that after a country achieves a certain stage of economic development, it stops degrading its environment. In the US, water use peaked around 1975 and levelled off for the next 30 years. It has declined about 25% from its peak usage, even though the economy tripled during that time; taking population growth into account, per capita use declined more than 50%. This dramatic reduction comes from industry and consumers following the soft path for water use.

Spurred by government regulations, industries now routinely recycle their wastewater. Power plants have eliminated once-through cooling and reduced the water required to produce a unit of energy. Improvements in appliance efficiency have reduced household use. In short, these soft path methods stop wasting water and change the way water is used. Natural soft-path methods include replenishing aquifers, many of which have been badly depleted during recent draughts, and restoring watersheds that both act as reservoirs and as the best cleaning systems for recycling groundwater. If the same soft path savings can be applied to agriculture, the world’s shortage of drinking water will be solved. But it takes some convincing for many in industry and agriculture to accept that restoring a watershed will provide them the water they need.

US water withdrawals compared with GDP 1900-2015

Water, Water Everywhere …

All of the water in the world is recycled water – it is the same water that was brought to Earth billions of years ago by asteroid collisions. The seas are salty because rain is very slightly acidic, and over time it dissolves rocks and washes the minerals into the ocean. Fresh water comes from the sea through evaporation, falling as rain and snow onto land. Humans copy part of this cycle by recycling wastewater. Treating wastewater even to levels where it is safe to drink is a well-established technology. Israel, long faced with a growing water shortages, recycles 85% of its treated wastewater. But Cape Town uses just 5% of its treated water, and California only 15%. If more water were recycled, it could be used to recharge depleted aquifers – in other words, saving for a not-rainy day.

Desalinization mimics another part of the water cycle by removing the salt from seawater. A few places like Kuwait, hot and dry but close to the sea, obtain almost all of their drinking water this way. Desalinization either forces seawater through a membrane that allows freshwater to pass but blocks the dissolved salt, or else it boils seawater and collects the fresh steam. There are environmental problems with both methods. In either case, concentrated brine is pumped out as waste, and the intake of great volumes of seawater can suck in and kill large numbers of marine life. Since most people live where fresh water is plentiful, or at least it used to be, for now desalinization is a last resort. It uses much more energy and costs much more than drawing on local water sources.

Treating wastewater even to levels where it is safe to drink is a well-established technology.

But the regions facing the greatest water shortages are, not surprisingly, in the hottest and sunniest climates. These water-stressed countries that also have high solar energy potential are in the Middle East and Africa, Asia and Pacific, and Latin America. They cover the range of economic development: from highly developed (Australia, Israel and Saudi Arabia) to some of the least developed (Afghanistan, Eritrea and Yemen). The desalinization that they now use is essentially all powered by fossil fuels, but pairing desalinization with their abundant solar potential would provide these nations with virtually unlimited fresh water at very low cost (admittedly after the considerable expense of construction). There has also been progress in reducing the environmental impacts of desalinization mentioned above, and low-cost renewable energy could be used to reduce any harmful effects even further.

Does This Taste Funny to You?

The great benefits of 20th century hygienic water infrastructure are in danger.

The warming climate is reducing the winter snow pack, not just in the mountains of California but around the world. The headwaters of the largest rivers in Asia that supply water to more than a billion people are in the glaciers of the Himalaya. More than 80% of the Himalayan glaciers are shrinking. But regions that have seen increased precipitation are also under stress because the increase often results in epic floods. This has overwhelmed drainage systems and dumped sewage into water sources. Toxic drainage flowing into shallow ocean waters has killed fish, fouled beaches, and repelled tourists in regions that depend on them for their economy. Climatologists have predicted these changes for decades, but scientists by nature are cautious, and the changes are happening even more rapidly than expected.

World map of changes in average annual precipitation since 2002
Changes in average annual precipitation since 2002 according to NASA’s GRACE satellite. The bluest areas are gaining about an inch per year, the reddest are losing about an inch per year. These trends are variable – Australia for example has been in a severe draught for the past five years. (Adapted from “The Future of Water” Trend report of the Pew Charitable Trust, Spring 2019 v4.)

The rapidly warming climate not only threatens to reduce the global supply of water, it also threatens the sources of existing fresh water, even in areas of abundance. The great benefits of 20th century hygienic water infrastructure are in danger. Rising sea levels in coastal regions cause severe flooding that compromises sanitation systems and mixes sewage into drinking water. Even today, more than one million people die each year from dysentery. Extreme droughts, too, can force people to use whatever water sources are available. There is an ongoing cholera epidemic in Yemen, the site of the water crisis described earlier, that the United Nations has designated the worst humanitarian crisis at present in the world.

The availability of clean, fresh water is something we take for granted. For a great many people, this is about to change. And as always, it is the poorest who will suffer the most.

Nature Does Not Compromise

It is within our power to solve the shortage of drinking water, but this alone will not fix the larger water problem. As the planet warms, water will become scarce where it was plentiful and rare where it was scarce, adding to the widespread disruptions in the natural world. The effects are too numerous to mention and will have many unforeseen consequences, but again perhaps one example can illustrate how the changes will be interconnected. Drought and warming temperatures are killing the vast lodgepole pine forests of North America. The countless dead and dying trees standing in hot and dry conditions have erupted into the largest wildfires on record. The loss of the forest watershed is reducing the amount of water stored in aquifers, and so there is even less clean, fresh water in a region that is already experiencing drought.

Victoria Falls before and after the drought of 2019

Victoria Falls, described as the largest waterfall in the world, as it appeared not long ago (left), and as it appeared in December of 2019 (right). Image credit: left, Diego Delso (detail), right, Zambia President Edgar Chagwa Lungu.

Fighting global warming by replacing fossil fuels with renewable energy will also save a great deal of water. Water usage in the state of Colorado provides a good example. Colorado has mandated that all electricity in the state come from renewable sources by 2040. Thirteen coal-fired plants have closed since 2010, with more expected to follow. These plants consume enormous amounts of water, and while most of it is returned to the environment, a lot is lost to evaporation – 6 billion gallons in Colorado alone in 2012. Trillions of gallons in total are diverted from rivers. The conversion to renewable energy sources will eliminate virtually all of this need for water, making it available for agriculture, industry, and residential and recreational use.

What to Do

In the fight against global warming and the need to adapt to fresh waters scarcity, it is our collective actions that matter most. The threats will not be resolved until governments take them seriously. Do not vote for politicians who deny the reality of climate change. Be skeptical of emotional appeals for large new infrastructure as the “obvious” solution to water shortage. We are naturally supportive of farmers, and agribusiness has traded on that sympathy to push for self-serving projects. For example, in the midst of California’s recent drought, Central Valley corporations blamed their reduced water supplies on conservationists. This came largely from growers who sold their almond crop overseas, while the local salmon came close to extinction because of water diversion from spawning grounds, and caused many fisherman to declare bankruptcy.

And there are steps we can take as individuals. Take advantage of the many government and industry programs that subsidize low-water use appliances. The single most important individual action we can take for the environment is to use less gasoline and other fossil fuels. Drive the speed limit or slower. This will save you money, and will even save lives. If you wish to donate money, consider supporting rainforest conservation. These global natural resources have been called the lungs of the planet and, among many benefits, are a critical component of the world’s hydrological cycle. Every day, in an act of collective insanity, they are being burnt to the ground. In large part this is clear land to raise more cattle, which also is water-intensive. If it suits you, eat less beef – this too will save you money, and perhaps also you will live longer as a result. Being a good citizen is not only good for the planet, it is good for you personally.

dried up Colorado River

The Lost River:
Mexicans fight for mighty waterway taken by the US

Nina Lakhani, The Guardian

The Colorado traverses seven US states, watering cities and farmland. Before reaching Mexico, the river is dammed at the border, and on the other side the river channel is empty. Locals are now battling to bring it back to life.

Featured Books:

The Future

Six Drivers of Global Change

Al Gore

No period in global history resembles what humanity is about to experience. Explore the key global forces converging to create the complexity of change, our crisis of confidence in facing the options, and how we can take charge of our destiny.

Our Choice

A Plan to Solve the Climate Crisis

Al Gore

We clearly have the tools to solve the climate crisis. The only thing missing is collective will. We must understand the science of climate change and the ways we can better generate and use energy.

The Big Ratchet

How Humanity Thrives in the Face of Natural Crisis

Ruth DeFries

Human history can be viewed as a repeating spiral of ingenuity—ratchet (technological breakthrough), hatchet (resulting natural disaster), and pivot (inventing new solutions). Whether we can pivot effectively from the last Big Ratchet remains to be seen.

The Sixth Extinction

An Unnatural History

Elizabeth Kolbert

With all of Earth’s five mass extinctions, the climate changed faster than any species could adapt. The current extinction has the same random and rapid properties, but it’s unique in that it’s caused entirely by the actions of a single species—humans.


The Economics of Renewable Energy in the U.S.
Energy Efficiency
The Planet We Inherited
The Human Footprint
The Rocky Road to a Sustainable Future

Further Reading

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