The world’s clean water supply is dwindling. In cities across the globe, the demand for potable water is outpacing what aquifers and other water reserves can provide. The implications this has for human life and the environment are huge. Having access to safe water is essential to community development and a key determinant of quality of life. The United Nations links water to all 16 of its Sustainable Development Goals, meaning safe water access plays an important role in eradicating a number of major social problems -- including poverty, gender inequality, and violence.
Unsafe water is also responsible for causing illness and death, especially in the global South. According to the Natural Resources Defense Council, unsafe water kills more people each year than war and all other forms of violence combined. Diseases like cholera, dysentery, typhoid, and polio are often spread by contaminated water. Having access to clean water is linked to greater life expectancy and increased well-being in nearly all areas of life.
The Water Quality and Quantity Crisis
Pollutants are a major cause behind the global decrease in clean water supply. Water, known as the “universal solvent,” is capable of dissolving almost anything, making it very vulnerable to becoming polluted. In many parts of the world, agriculture is the leading cause of water pollution. Stormwater runoff often picks up toxic chemicals used in agriculture and carries them to rivers and streams, polluting them with fertilizers, pesticides, and antibiotics. Stormwater runoff can also pick up other toxins like gas and oil from city streets and carry them into waterways. The industrialization of agriculture and the expansion of cities has increased the amount of pollution in global waterways. According to the U.S Environmental Protection Agency, half of all rivers and streams and one-third of all lakes in the United States are unfit for swimming, fishing, and drinking.
Water scarcity is also a concern in many parts of the world. Water is a finite resource, and currently water distribution capacity does not match the population’s demand. Overall population growth, urbanization, and climate change have all contributed to reducing the world’s water supply. From a climate perspective, global warming has caused extreme drought in many parts of the world. California, for example, is in the midst of an unprecedented drought, and its aquifers and ground-water reserves are drying up at an alarming rate. Nevada’s Lake Mead -- a crucial source of clean water for millions in the West -- is 165 feet below “full pool” and continuing to drop. Consequently, in California and in many other places, the population’s demand for water is outpacing water resources, leading to increased water restrictions and other mitigation tactics.
“The droughts that are happening in places like California have created a number of ecological problems,” said Ernest (Chip) Blatchley, the Lee A. Rieth Professor in Environmental Engineering at Purdue University’s Lyles School of Civil Engineering. “When surface and groundwater disappears, it can lead to soil collapse and changes in elevation. The massive wildfires that have become commonplace in the western U.S are also worsened by drought. These ecological changes make living in this region more precarious.”
Clean water scarcity is an issue that affects more than the American West. Cities all over the world are struggling to provide their populations with clean and accessible drinking water (take, for example, the case of Flint, Michigan). Water shortages have also strained commercial industries like farming and manufacturing, which are among the largest consumers of water. All the while, the population continues to grow and the global climate crisis continues to worsen. There has never been a more crucial time to develop creative, effective, and sustainable solutions to optimizing and expanding our water supply. Smart engineering focused on reusing and recycling waste water may be the key behind creating a more water-abundant future.
Engineering Sustainable Water Solutions
Scientists and engineers are employing new and old technologies to make potable water from new sources, recycle and reuse waste water, and reduce the amount of pollutants flowing into rivers and streams. Because there is a clean water shortage in many parts of the world, developing methods for purifying wastewater has become necessary. The technology that exists to purify wastewater is generally very safe and effective, but there’s still room to improve -- especially when it comes to public attitudes towards drinking recycled water.
In Singapore, scientists and engineers have developed effective and efficient membrane-based technology that can purify wastewater for reuse. This treatment approach, called NEWater, meets 30% of Singapore's potable water needs. Additionally, Singapore has launched a robust PR campaign aimed at showing citizens that recycled water is safe to drink. Singaporean officials have been shown drinking NEWater to publicize their support for the new technology.
“Water is a finite resource,” said Blatchley. “We cannot produce more of it, and so it’s incredibly important that we care for the water supply that we have. Creating technologies that enable us to safely and efficiently recycle wastewater is essential, especially as urban areas continue to grow. Water recycling allows us to turn water sources that were once thought of as unsafe into clean drinking water that can support the needs of cities all over the world.”
Water reuse and recycling can also be supported by green technologies that naturally collect and purify rainwater and storm runoff. Stormwater runoff is a major cause behind pollution in rivers, lakes, and streams. When stormwater falls on city streets and other hard surfaces, it fails to be absorbed into the ground and can travel to waterways, picking up any pollutants in its path. Green spaces -- such as meadows, forests, and parks -- naturally absorb stormwater, which is then purified by plants and soil. Establishing more green spaces in urban areas can help reduce stormwater runoff and improve the quality of freshwater sources. Building “green roofs” and rain gardens are two common ways people living in cities support stormwater absorption.
Stormwater can also be collected and reused for a variety of purposes. Rain barrels are a relatively simple way to collect rain and can be added to almost any home. The water that rain barrels collect is not purified, meaning it can’t be used for drinking or cooking. However, recycled stormwater can be used for things like flushing toilets and watering lawns. Stormwater can also be purified after it’s collected using wastewater recycling technologies. Currently, the densely populated city of Los Angeles is capturing stormwater, purifying it, and using it to refill drinking water aquifers. In a part of the country where clean water is scarce, recycling programs like these are lifesaving to millions.
Recycling wastewater can also recover other valuable resources, like nitrogen, sulfur, and heat. “When hot water is recycled, we can harvest and reuse the heat for other purposes,” said Blatchley. “Wastewater contains many chemical elements that are useful to humans, and so creating recycling processes that can both clean wastewater and extract any chemical resources it contains is important.”
“There are a lot of exciting improvements that can be made in the future,” Blatchley said. “Improving these technologies and making them more accessible stands to benefit everyone.”
The Future of Sustainable Water Engineering
Though the trajectory of water reuse and recycling is promising, there are still many problems that need to be solved when it comes to current methods and technologies. “Wastewater treatment facilities and potable water production facilities are among the largest consumers of electric power,” Blatchley said. “People are now much more concerned about conserving energy than they were when some of these facilities were built.” According to Blatchley, figuring out ways to reduce the carbon footprint of the water infrastructure, as well as finding new water sources that can be transformed and repurposed are also central goals for water sustainability engineers.
“It’s a great time to join the field,” Blatchley said. “There is a lot of innovative work that can be done here, and the real-world impact is huge. Everything starts with water.”
Purdue University's award-winning College of Engineering offers a track in Sustainable Water within its online Master’s of Science in Civil Engineering degree. The program includes fully online courses in both water quality and water quantity improvement, all taught by Purdue’s distinguished engineering faculty. Learn more at the program’s website.