Why are we running out of water?

Water is essential to human life, and, lucky for humans, it’s also a renewable resource. Our planet comes equipped with a naturally occurring cycle that circulates and recycles all the water on Earth. This handy feature maintains the finite supply of our most vital resource and distributes it around the world.

It sounds ideal, right? While it’s a system that has sustained human life for, well, forever, it’s not perfect, and it can be dangerously disrupted by a range of factors. We’re finding this out right now, as we face a crisis of water scarcity. There are currently 2 billion people in the world facing extreme water stress, and that figure is projected to double by 2050, according to Samantha Kuzma of the World Resources Institute. In the US, most state water managers are bracing for water shortages this decade, and the Southwest is experiencing a historic drought. What’s driving all this?

First, let’s back up a bit and look at the water supply in question: It’s actually just a tiny fraction of all the water on Earth. Even though water covers more than 70% of the globe’s surface, most of that water—more than 97% of it—is not usable because it’s salt water. The bulk of the remaining 2.5% is frozen in glaciers or locked up in the ground. That leaves less than 1% of the global water supply available for human use. While this sounds paltry, it’s been enough to sustain life on the planet for millennia.

“When the climate system provides enough water to meet demand, then we’re in a sustainable state and we don’t really worry too much about having water,” says Dr. Benjamin Cook, climate scientist at the NASA Goddard Institute for Space Studies. When regions aren’t getting enough water naturally, or are using more than they’re getting, water stress and even water crises can follow. Problems in the water cycle are, generally speaking, supply-and-demand issues.

While there are several factors currently disrupting this dynamic, climate change may be the main culprit. “[Climate change] kind of supercharges the patterns that are already there,” says Dr Cook. “In the Western United States, where things are already naturally dry, climate change is increasing evapotranspiration and drying things out even further.”

Indeed, Western North America is currently in the midst of a mega drought not seen in 1200 years. “The entire region has been in more or less continuous drought conditions since the turn of the 21st century,” says Dr Cook. “And because of this, we’ve seen declining aquifers, we’re seeing drying-up rivers, and we’re seeing these incredibly low levels in many of the most important water reservoirs in the region.”

While climate change is making dry places even drier, it’s also doing the opposite in other regions, leading to heavy rainfall and flooding, which can interfere with the water supply as well. “Flooding can overflow pollution beds—say, on large industrial farms that hold the waste from hogs or chickens,” says Dr Cook. “This can then get into streams in the groundwater and lead to conditions where the water is not so safe to drink.”

A significant disrupter on the demand side of the equation is population growth. There are just shy of 8 billion people on Earth at the moment, with that total expected to approach 10 billion by 2050. More people, more demand for water. This will have a ripple effect across several areas, starting with the agriculture industry, which already accounts for 70% of freshwater usage—and will need to feed the two billion additional people.

The booming population will also put stress on infrastructure, a third major factor contributing to water scarcity. Infrastructure issues such as leaky pipes, pollution, inefficient irrigation systems, and failure to recycle wastewater put significant dents in the water supply worldwide.

Water scarcity is real, and growing, but it’s a challenge we can meet—at the individual, municipal, and industrial levels. Families can switch to water-saving appliances, like Moen’s kitchen and bathroom faucets, which use up to a third less water. Businesses can adhere to regulations and modify their technologies to maximize conservation.

At the municipal level, Ms. Kuzma points to Singapore, which lacks a robust water supply, as a model for efficient resource management. “There are other places, including Las Vegas in the United States. These places … have thought a lot about how they could manage the resource. It shows us that water stress isn’t our destiny. It is something we can manage, but we have to be actively managing and actively thinking about it.”