Climate change is no longer an existential threat in theory; it’s already negatively affecting us. Just take a look at recent years’ unprecedented fires, heat waves, hurricanes, sea level rise, and more. While it may seem as though you’re immune to them if, say, you don’t live in areas that are prone to fires or flooding, there isn’t a single part of the country that will be spared from new climate-related challenges in coming years. And the most widespread impact is one you might not even have on your radar: water stress.

Water stress (or scarcity) may struggle to get the same airtime as raging fires that decimate homes and blacken the skies, but it should be on your radar nonetheless. Here, experts explain what it is, why so much of the U.S. will experience it in our lifetimes, and just how worried you should be.

What is water stress?

Water stress, as Heather Cooley, director of research at the Pacific Institute, explains is, at its most basic, a measure of water supply versus water demand. “Water stress occurs when demand exceeds, or is nearly equivalent to, the available supply over a long period,” she says. This is different from, say, a temporary and unusual drought. “You can have these short-term periods that you need to manage, but that’s different than water scarcity, which is perpetual,” Cooley explains. It’s also important to note that a region can be dry without experiencing stress if its population has learned to manage the relatively meager water supply at their disposal, says Newsha Ajami, PhD, director of urban water policy at Stanford University.

Water stress is worrisome for a number of reasons. The most obvious is that all living beings—from humans to animals to plants—require water to live. When access to clean drinking water is threatened, so too are the populations which rely on it. Water shortages can also lead to sanitation issues (think hand washing and sewage), affect food safety and availability, cause or exacerbate conflict, and lead to mass migration. Much of industry—including energy production—also requires water use.

Half the world’s population is projected to be living in water-stressed areas as soon as 2025.

The complex causes of water stress

The World Health Organization projects that half the world’s population will be living in water-stressed areas as soon as 2025. And according to U.S. government projections, this problem will affect just about everyone in America west of Missouri by 2040.

The U.S. projections rely on two factors to determine whether regions will experience water stress in coming years: shifts in drought-like conditions (due to climate change) and population changes. These aren’t the only factors that contribute to water stress, however. Below, Cooley and Ajami unpack its various causes, and how they work together to create strain on water supply.

1. Climate change 

Water supplies are threatened by the weather events caused by climate change, including drought, extreme heat, flooding, and sea level rise. Most notably, droughts affect a region’s ability to replenish its supply. If there’s no precipitation, there is no way to replace the water being pumped out to homes, crops, and industry. High temperatures affect a region’s ability to retain precipitation, as heat leads to faster evaporation. It also causes plants to transpire (aka sweat) more, which makes crops (and non-food plants, too) require more water. Events like flooding and sea level rise, meanwhile, can lead to water supply contamination.

“People say, ‘If climate change is the shark, water is the teeth,’ and that’s very true,” says Ajami. “People are impacted by hurricanes and extreme rainfall and flooding and sea level rise, but also water stress.”

2. Population growth

As populations grow in regions large or small, water supplies can strain, and stress modeling tends to take into account expanding populations over time.

This doesn’t have to be the case, however. “If you look at Los Angeles today, they’re using less water than they were 30 years ago, despite a much larger population,” Cooley says. “They’ve done a lot in terms of conservation and efficacy, and there’s not as much manufacturing in Los Angeles as there used to be.”

3. Overuse of groundwater

Populations, Ajami explains, obtain their water supply from two sources: surface water and groundwater (aka, underground water). Some populations, she explains, have been overusing groundwater to make up for shortfalls in surface water (due to increased heat, drought conditions, unsustainable agricultural practices, etc.).

This is already happening in parts of California, Cooley explains, particularly in agricultural regions. She says to think of this like a bank account. If those areas keep making withdrawals without enough deposits (via precipitation, melted snowpack) to counter them, they will find themselves dangerously in the red. You can also picture getting all of your water from a well that is not replenishing through rainfall or other means; eventually, it will run dry.

4. Narrow supply options

When a region relies on too few water sources, this can become problematic if anything happens to threaten those sources. Cooley says, for example, that years ago, Atlanta, Georgia, was actually within 90 days of running out of water because the entire city had relied mainly on just one water source, which ran low due to drought.

5. Infrastructure issues 

Providing water to communities requires quite a bit of infrastructure, and Cooley explains that many regions are in need of investments in updating theirs to expand capacity and improve efficiency.

6. Water pollution 

Pollution can also lead to water scarcity. “Some industrial practices inadvertently impacted groundwater quality,” says Ajami. “And now that we need that groundwater to augment the water supply, we’ll see that we can’t use it because it’s polluted.” Los Angeles, she notes, offers an example. “The [city’s] San Bernardino groundwater basin is polluted,” she explains. “LA has been trying to clean it up for a while to be able to use it as a water supply.”

Where water stress exists right now

Many regions globally already experience water stress to varying degrees. Seventeen countries—primarily in Africa and the Middle East—are currently under extremely high water stress. Places like Qatar, Israel, and Lebanon are basically already using all of their water each year. And while the United States as a whole is not in trouble, five of its states—New Mexico, California, Arizona, Nevada, and Colorado—are also experiencing high levels of water stress.

In 2018, Cape Town, South Africa, approached a “day zero” on which the city was projected to run out of water—as in, all taps would run dry, and citizens would have to line up for water rations. Something similar, though less urgent, happened closer to home not too long ago, too. California found itself in danger of a further-in-the-future day zero after several years of drought. In both cases, public conservation messaging and restrictions as well as innovation and improvisation by local authorities managed to avert crisis, and most citizens were merely inconvenienced by having to reduce their water use (Cape Town residents did so by 50 percent). In other words, no one went thirsty. The city of Chennai, in India, was not so fortunate in 2019, however; it did reach a day zero, at which point citizens had to line up for water rations they could access every three or four days.

And while these urban regions experience water stress dramatically, their rural neighbors—those who rely on well water and don’t have as much government infrastructure to support them—can find themselves in deeper trouble. During that aforementioned California drought, some rural residents went without water for days. “Small and medium-size [communities] struggle the most,” says Cooley. 

What the future might hold

In coming years, things are only going to get worse (at least from a climate perspective) for the places that currently experience water stress, and areas where it has never been a problem will have to deal with it for the first time. This means that places like Nebraska and Minnesota will join more obviously dry states like California and New Mexico in running low on water stores based on at least the two criteria of warmer, drier weather and population increases. The breadth of this problem, as illustrated by this map, is pretty breathtaking.

Places like Nebraska and Minnesota will join more obviously dry states like California and New Mexico in running low on water stores.

Those of us who live in the United States are not really, however, in danger of running out of water to the point at which we’d have no recourse. We’re not going to die of dehydration. Overall, the states are only currently using 20 percent of their total water supply, so we are not in the same position as some African or Middle Eastern countries by any stretch. (That is, as long as we remain united and dedicated to sharing resources.)

There are likely to be growing pains as regions adapt to the new challenges presented by water stress and, ultimately, Cooley says the price of water is going to continue to rise. Still, water is relatively cheap (“Less than your cable bill,” Cooley says) and most American households don’t have trouble affording it. “But there are households that struggle to pay for basic water and wastewater service, and that’s something we have to address,” she says, especially as prices rise to reflect increased scarcity.

As water becomes less available to communities globally, Ajami says we are likely to see an increase in conflict. For example, while dam building rarely happens in America anymore, it’s just starting to pick up in Africa. This, she explains, is creating challenges for countries that depend on a single water source, which is getting drier, that is now being dammed up in another country. “These practices might help a country for 40 or 50 years, but eventually it will become a problem rather than a solution,” she says. “We need to figure out how to coordinate strategies to make sure that globally, people have access to more innovative solutions. And in some cases, we need to promote local practices, because the reality is that local solutions are sometimes much more sustainable than global solutions that are exported to these regions.”

How to solve the water stress crisis

To some degree, the amount of water stress we will experience depends upon what actions (like voting in politicians and supporting policies that aim to lower emissions) we take now. The rest depends on adaptation. “There is a way to become more efficient and effective in the way we use resources,” says Ajami. “We just need to make sure to do it.”

Much of what will need to be done is quite dry (pun intended) in that it involves expanding and updating infrastructure. Regions will need to ensure they’re reliant on multiple water sources, which will make them more resilient to water supply challenges down the road, find solutions for decreasing their demand, and update their pipes and pumps.

This may require throwing quite a bit of money at the problem, Cooley says, especially in areas with aging infrastructure that needs to be pulled out and replaced. “I will say, though, that the need to reinvest in our system does provide an opportunity to rethink how we manage water, to look at more distributed types of infrastructure,” she says. “The old way was very centralized—you have one big wastewater treatment plant, for example—and now there is a movement to think about smaller treatment plans or neighborhood-scale water recycling plants, etc.” She also notes that water stress-alleviating measures can piggyback on other green initiatives. For example, stormwater capture can be a feature of public parks, so that a publicly funded area is pulling double duty as a water-collecting and recreational space. Plus, she says, green energy sources, like wind and solar, use very little water when compared to coal or natural gas power plants.

Cooley is optimistic about the ability to adapt given the public and political will to do so, because it’s already been done in places like Los Angeles, which supports a large population on little regional water supply. “We’re seeing communities that are rising to the challenge,” she says. “The Los Angeles example is a good one. They’re diversifying their [water] portfolio, investing in efficiency, looking at rain use, and so on.”

We’re going to have to figure out how to use less water overall.

In San Francisco, she points to exciting innovations, the likes of which will become more common in coming decades. For example, the city requires that large buildings of 250,000 square feet or more install their own on-site water systems. “Those systems are either taking in gray water [the relatively clean wastewater from household or office use] or other types of wastewater and treating it for reuse on site,” she says. This has the added benefit of shifting the cost of expanding and evolving water infrastructure from the community to the private developer.

These types of changes likely won’t be enough in many of the most at-risk areas, however. We’re going to have to figure out how to use less water overall, too. Cooley tells me this is especially true when it comes to our agricultural practices, as they suck up about 70 to 80 percent of our H2O. “There are a lot of opportunities to be more efficient and practice reuse and other strategies, but we’re also going to have to rethink how much we’re growing and where and how we’re growing it,” she says.

Individuals and communities will have to figure out how to make their water budgets stretch more by “spending” less, too. “The more we can meet our water needs with existing resources, the better it is,” says Ajami. “For the past few centuries, we have tried to conquer nature, to use all these engineering solutions to what we want, and keep the nature out. But I think we’re realizing right now that our solution actually has to have nature in its heart, because the reality is eventually, we can’t really engineer our way out of our limitations.”  

Conservation doesn’t have to be painful, however. As mentioned above, Los Angeles citizens have already significantly cut their daily water usage (by about a third, Ajami estimates), and yet I, an Angeleno, am looking out on a green neighborhood while drinking tap water after taking a relatively indulgent shower. In other words, I’m not missing those 60 or so gallons per day residents used to spend. San Francisco, meanwhile, is currently using just a third of what we use in Los Angeles, which also means there’s room to grow (or rather, shrink usage) without feeling strapped for water.

And while it’s possible to use conservation to triage a water crisis the way California and Cape Town did during their recent droughts, the key is putting conservation systems in place and adopting those habits before the situation becomes dire.  But Ajami does note that such extreme situations can help communities wake up to the reality that they need to make major changes. “You don’t want a day zero—that’s terrifying,” she says. “But people don’t think about what it takes to bring them water, and that disconnect is a big challenge because it diminishes the capacity for people to think about the consequences of their actions. If the water is only coming out of their tap two hours a day, they’re going to be making different decisions.”

Here’s what you can do right now

Though avoiding water stress requires large-scale interventions, there are steps we as individuals can take now. “It does make a difference, so think about the ways you’re using water inside your home, but also outside your home,” Cooley says. “If you look in our urban areas, about 40 to 50 percent of our water use is outdoors. Some of that is for parks, but most of it’s for ornamental lawn that nobody ever uses.” You can also look at how water is being used where you work and get involved to make changes there, too.

And because water is locally managed, she notes that it’s also important to get involved at the community level. Local boards are in charge of those decisions around water and wastewater systems, including how they’re built, who’s paying for them and how, and what consumer rates are going to be. “There’s absolutely an opportunity to shift towards a more resilient and sustainable community,” she says. 

Ultimately, Ajami says, we need to understand that the underlying assumption of our nation’s water system is dangerous. “That sense of abundance is a big problem,” she says. “Water is a finite resource, and you have to be mindful of how you use it.”