Water

A tiny, vibrant world thrives along the rocky bottom of most streams. As sunlight filters through the water, mayfly nymphs, no larger than your fingernail, cling to algae-coated cobbles. Their brushlike mouthparts scrape the greenish coating, leaving faint trails as they feed. Six spindly legs anchor them against the current, while feathery gills wave gently, drawing oxygen from the flowing water. This scene is common in well-maintained creeks and streams that flow through populated areas. But when wildfires sweep through, the toxic materials left behind can devastate this ecosystem. When you think of urban wildfires, you might picture charred trees and houses. But beneath the surface of nearby streams, fires can also cause a silent upheaval – one that affects populations of creatures that are important indicators of the water’s health. Images of some of the benthic invertebrates that help keep streams healthy, and whose disa...

The wildfires that burned across Maui, Hawaii, in August 2023 became the deadliest conflagration in the United States in more than a century. While the harm to homes and tourism drew the most attention, agriculture was also heavily affected across the island, and the harm did not stop once the flames were out. In some cases, fires smoldered underground for weeks. Water systems were destroyed, and some were contaminated in ways scientists are only beginning to understand. Two weeks after the Maui fires began, they were still smoldering below ground. Andrew Whelton/Purdue University, CC BY-ND As an environmental engineer, I work with communities affected by wildfires and other disasters. I also led a team of university and public works professionals to assist in Maui’s response to the fires. In a new study based on that effort, my team worked with the Hawaii Department of Agriculture to assess d...

The Caribbean’s sandy beaches, clear turquoise water and vibrant coral reefs filled with an amazing variety of sea creatures have long been the pride of the islands. The big three – sun, sea and sand – have made this tropical paradise the most tourism-reliant region in the world. But now, all of that is under threat. The explosive growth of a type of seaweed called sargassum is wreaking havoc on economies, coastal environments and human health across the islands. I study the intersection of critical infrastructure and disasters, particularly in the Caribbean. The sargassum invasion has worsened since it exploded in the region in 2011. Forecasts and the seaweed already washing up suggest that 2024 will be another alarming year. Sargassum levels were already high around many eastern Caribbean islands in late May 2024. Forecasters expect increasing sargassum washing up in June on many of the islands and in the Gulf of M...

Chemists invented PFAS in the 1930s to make life easier: Nonstick pans, waterproof clothing, grease-resistant food packaging and stain-resistant carpet were all made possible by PFAS. But in recent years, the growing number of health risks found to be connected to these chemicals has become increasingly alarming. PFAS – perfluoroalkyl and polyfluoroalkyl substances – are now either suspected or known to contribute to thyroid disease, elevated cholesterol, liver damage and cancer, among other health issues. They can be found in the blood of most Americans and in many drinking water systems, which is why the Environmental Protection Agency in April 2024 finalized the first enforceable federal limits for six types of PFAS in drinking water systems. The limits – between 4 and 10 parts per trillion for PFOS, PFOA, PFHxS, PFNA and GenX – are less than a drop of water in a thousand Olympic-sized swimming pools, which speaks to the chemicals’ toxicity. The...

Climate change is threatening America’s water infrastructure as intensifying storms deluge communities and droughts dry up freshwater supplies in regions that aren’t prepared. Severe storms that swept through the South in April 2024 illustrated some of the risks: In New Orleans, rain fell much faster as the city’s pumps could remove it. A water line broke during the storm near Hattiesburg, Mississippi. Other communities faced power outages and advisories to boil water for safety before using it. We study infrastructure resilience and sustainability and see a crisis growing, particularly in the U.S. Southeast, where aging water supply systems and stormwater infrastructure are leaving more communities at risk as weather becomes more extreme. Neighborhoods across the New Orleans area flooded on April 10 as the region’s pumps couldn’t keep up with the rainfall. Credit: Reed Timmer. To find the best solutions and b...

If you stand at practically any point on Earth, there is water moving through the ground beneath your feet. Groundwater provides about half of the world’s population with drinking water and nearly half of all water used to irrigate crops. It sustains rivers, lakes and wetlands during droughts. Groundwater is a renewable resource, but it can take decades or even centuries for some aquifers to recover after they are depleted. Current understanding of this challenge is based mainly on where and how frequently people record measurements of water levels in wells. In a newly published study, our team of data scientists, water specialists and policy experts compiled the first global-scale dataset of these levels. We analyzed millions of groundwater level measurements in 170,000 wells located in over 40 countries and mapped how groundwater levels have changed over time. Our study has two main findings. First, we show that rapid groundwater depletion is widespread around the worl...

A lot can go wrong in a large urban water system. Pumps malfunction. Valves break. Pipes leak. Even when the system is functioning properly, water can sit in pipes for long periods of time. Water shortages are also a growing problem in a warming world, as communities across the Southwestern U.S. and in many developing nations are discovering. That’s why cities have started experimenting with small-scale alternatives – including wastewater recycling and localized water treatment strategies known as decentralized or distributed systems. I study large- and small-scale water systems, focusing on innovative system designs that allow local use of water sources that might otherwise go to waste. As technology improves, cities are discovering something that rural communities have long known: Small-scale water treatment, properly engineered, can be cheaper and easier to maintain than a centralized system, and it can improve water security and even the environment. Cleaning w...