December 5, 2025

According to research by the Interstate Commission on the Potomac River Basin (ICPRB), the region’s water supply could fail to meet the needs of the region as soon as 2030 in the event of an extreme drought.

ROCKVILLE, MD (December 5, 2025): While most people don’t think twice about where their water comes from — or if it will come at all — when they turn on the tap, new research notes that changing weather patterns and increased water demand are putting a strain on the region’s water supply. This may have dire consequences without strong investment in water infrastructure according to a new report by the Interstate Commission on the Potomac River Basin (ICPRB), an organization tasked with producing a report every five years on the region’s water supply.

The report, 2025 Washington Metropolitan Area Water Supply Study – Demand and Resource Availability Forecast for the Year 2050, shows that the region will have plentiful water most years, but there is an increasing chance — up to about 1 percent in 2030 and up to about 5 percent in 2050 — that there will be water shortages. This is when there is not enough water to meet the demands of the water users while still leaving enough water in the Potomac River to protect the sensitive aquatic habitat below Little Falls Dam.

Actual Washington metropolitan area annual water demand (blue dotted line), ICPRB’s 2025 forecast (blue solid line), with actual and forecasted population (gray dotted line).
(Source: ICPRB)

According to the report, despite exponential growth in the region, overall water use has stayed remarkably stable over the past several decades due to the use of low flow fixtures and appliances. However, the researchers predict an increase in water demand in the coming decades, with a 17 percent increase in water use by 2050.

In addition to more overall use, the river’s flow may be impacted by predicted changes in temperature and precipitation through a process that has been characterized as “hot drought” by ICPRB.

“Results from our study indicate that extreme hydrological droughts may become more severe due to increasing temperatures,” explains Dr. Cherie Schultz, Director of ICPRB’s Section for Cooperative Water Supply Operations on the Potomac.

“A major uncertainty in many regions, including the Potomac, is the response of future stream flow to the competing effects of temperature change and precipitation change. Rising temperatures will tend to decrease flows due to increases in evaporation, while predicted increases in precipitation will tend to increase flows,” continued Dr. Schultz.

“It is changing weather patterns combined with the increase in demand that may be putting the whole system at risk,” states ICPRB Executive Director Michael Nardolilli.

Data center growth is also contributing to the uncertain future of the region’s water supply, both upstream and within the Washington metropolitan area. The study finds that upstream data center water use is expected to grow over time and could become comparable to several established water-using sectors, such as commercial, industrial, and thermoelectric facilities. These estimates are based on grid-connected energy forecasts, which are rapidly evolving as the sector continues to expand. In the Washington metropolitan area, data centers could use as much as 80 million gallons on peak days by 2050. This could signal the growing significance of data centers in the region’s water demand. The report notes that balancing energy, water, regulations, and infrastructure constraints may be needed to strengthen resiliency in this sector. One step forward would be to improve transparency around data center water use.

The majority of the Washington metropolitan area’s water supply is provided by the Potomac River. While most regions have two or more sources of water, the Potomac River is the only source of drinking water for the residents of Washington D.C. and Arlington County.

Two upstream reservoirs, Jennings Randolph and Little Seneca, are available to release water to augment Potomac River flow should the river get too low to meet the region’s demands. In addition, off-Potomac reservoirs, Fairfax Water’s Occoquan Reservoir and WSSC Water’s Patuxent reservoir, are used to partially meet these suppliers’ demands. According to the study, four out of nine modeled scenarios predict that in the event of an extreme drought, the upstream reservoirs will run out of water as early as 2030, indicating that short-term measures should be taken to improve reliability.

Some short-term solutions are already in the works. Improvements in ICPRB’s river flow forecasts can help water resource planners better predict when to release water from upstream reservoirs. A water reuse project recently announced by DC Water, dubbed Pure Water DC, aims to create a more resilient water source for residents of the District. Two drinking water reservoirs currently in the planning stages, Loudoun Water’s Milestone Reservoir (expected operational by 2028) and Fairfax Water’s Edgemon Reservoir (expected operational by 2040), were already included in the report’s calculations.

The U.S. Army Corps of Engineers, Baltimore District, initiated a D.C. Metropolitan Area Backup Water Supply Feasibility Study last fall which could lead the way to possible long-term solutions. However, with federal funding issues hanging in the balance, it is unclear when that study will be completed.

“For nearly 170 years, the Washington Aqueduct has been committed to executing its critical mission to produce safe, reliable, and high-quality drinking water for approximately one million citizens living, working, or visiting the National Capital Region,” said Washington Aqueduct General Manager Rudy Chow. “Increased water resiliency standards are a vital part of our commitment to public health and safety, national security and the wellbeing of local populations. We are in close collaboration with our regional utility partners as we continue our ongoing Washington D.C. Metropolitan Area Backup Water Supply Feasibility Study, aimed at developing coordinated and implementable solutions that ensure abundant water supply, including the identification of a secondary water source and additional water storage capability.”

“We can no longer ignore the fact that parts of the DC region have only one source of drinking water – the Potomac River – and just a one-day back-up of water supply. Today’s release of the 2025 Washington Metropolitan Area Water Supply Study highlights the need to expedite the study so that we can reduce the vulnerability of the DC region from a cutoff of drinking water because of drought or contamination events (both accidental and deliberate),” explained Nardolilli.

“This report confirms the need for innovative and cooperative approaches, as well as funding, to secure the water supply for our region,” said WSSC Water General Manager and CEO Kishia L. Powell. “The Potomac River has provided the vast majority of the region’s drinking water for generations. But climate pressures and growing demand will impact our ability to meet the region’s needs in just a few years. This report makes clear that we need to continue with substantial investments to safeguard public health, enhance reliability and resiliency, and ensure the long-term economic vitality of the region.”

An earlier study released by ICPRB found that a significant water supply disruption could result in losses of almost $15 billion in gross regional product and hundreds of millions in tax losses, all within the first month.

“For nearly 50 years Fairfax Water, WSSC Water, the Washington Aqueduct and ICPRB have been working together to ensure adequate water supply for the Washington Metropolitan Region now and into the future” said Fairfax Water General Manager and CEO Jamie Bain Hedges. “This study further advances our collective mission to supply life’s most essential service for decades to come.”

The water supply study released today is conducted every five years by the Section for Cooperative Water Supply Operations on the Potomac (CO-OP) of the Interstate Commission on the Potomac River Basin (ICPRB) on behalf of the three major water suppliers: Fairfax Water, WSSC Water, and the Washington Aqueduct. This is the first year that the study has explored the impacts of data centers on the water supply.

New Study: 21 Global Water Scarcity Hotspots Identified, Classified into 7 Hotspot “Clusters” with Shared Water Challenges

New research from Utrecht University, supported by the National Geographic Society’s World Water Map and Freshwater Initiative, found common drivers of water scarcity can help inform common solutions

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Photo by Charlie Hamilton James

WASHINGTON, D.C. (April 25, 2024) – A new study released today identifies 21 global water scarcity “hotspots,” where there is a significant “water gap” between human demand for water and renewable available supply. The team of Utrecht University researchers analyzed each of the 21 hotspots to determine what’s driving water scarcity at each location. Hydroclimatic change, population growth, and agricultural, domestic, and municipal water use are the biggest pressures affecting both the quality and quantity of available water, researchers found. The study in Environmental Research Letters also classifies the 21 hotspots into seven “clusters,” based on common drivers of water scarcity.

About one third of the global population is affected by water scarcity for at least one month per year. In these areas, the overuse of freshwater resources can lead to a “water gap” and threat of depletion, making them global water scarcity hotspots, said the study, which is supported by the National Geographic Society’s World Water Map and Freshwater Initiative.

Researchers identified the 21 hotspots through a combined approach of hydrological modeling and a literature review of 300 case studies. Hotspots were classified as water provinces where the water gap exceeds 0.015 meters per year. Additionally, to identify and characterize hotspot clusters by similarities and differences, the team applied a Drivers, Pressures, States, Impacts and Responses (DPSIR) framework to the literature.

Example of the most important water scarcity Drivers, Pressures, States, Impacts and Responses (DPSIR) in the Indus Basin. The colors of the text boxes with system processes correspond to the respective DPSIR component from the legend in the bottom right. Black arrows in the legend indicate how DPSIR components affect each other. Colored arrows in the figure give spatial direction to corresponding system processes. Image courtesy of Utrecht University.

Myrthe Leijnse, Utrecht University

“We started with two questions: where does water scarcity occur, and why is it happening? While we found water scarcity has similar drivers in some hotspots, the impacts on people, ecosystems, and economies – as well as societal and policy responses – could vary widely place to place,” said Myrthe Leijnse, the lead author of the study and a researcher at Utrecht University. “We hope this study demonstrates to policymakers that if there are common contributors to water scarcity, there could be common solutions to addressing it.”

The seven “hotspot” clusters are:

1. Water treatment and desalination: Arabian Peninsula. Unlike other hotspots, this region faces a unique combination: low natural water availability (highlighted in 89% of case studies) and high per capita water consumption (42%), leading to groundwater depletion and reliance on unconventional water sources (desalination and water treatment). Economic growth from oil and natural gas discovery has also fueled urbanization and population growth, further intensifying water demand.
2. Hydroclimatic change: Central Chile, Spain, Murray-Darling (Australia), Japan. These hotspots have faced consecutive droughts and a decline of total annual rainfall. At the same time, these hotspots have effective acts and agreements that support sustainable use of water resources (including water treatment, water rights, and increased storage capacity). Unlike most other hotspots, population growth is not a major driver of water scarcity in these locations.
3. Agricultural water use: North China Plain, Central Valley California, US High Plains, White Nile Sudan, Nile Delta, Italy, Greece, and Turkey. This is the largest cluster by number of hotspots, containing eight of the 21. Their single commonality is high agricultural water use (mentioned in 29-100% of case studies).
4. Population growth: Indus and Ganges River Basins: The Indus and Ganges River Basins have experienced rapid population growth over the last decade (reported in 40-67% of case studies), impacting society and the ecosystem. Water scarcity has led to reduced food production (24-33%), conflict and migration (28-33%), and health concerns (17-56%). The lack of water regulation has also resulted in unregulated private wells and subsequent groundwater depletion (52-61%).
5. Surface and groundwater depletion: Coastal Peru and Iran. Peru and Iran are the only hotspots where both surface and groundwater depletion are reported in over 60% of case studies. Both hotspots report contamination and salinization of water resources. Conflict and rural-urban migration (45-50%) are also prevalent due to water scarcity and inequality of water supply.
6. Land subsidence: Mexico, Java (Indonesia), and Vietnam. All show above average values of industrial (30-71%), municipal (40-75%) and agricultural (70-100%) water use. While these values are also reported in other clusters, Mexico, Java and Vietnam have one common impact that is unique compared to other hotspots: land subsistence (10-27%), the gradual settling or sudden sinking of the Earth’s surface. This is likely due to groundwater overexploitation.
7. Virtual water trade: Thailand. In Thailand, virtual water trade (43%) is a significant factor driving water scarcity. Thailand is one of the world’s biggest rice exporters, shipping about one third of its rice production. However, case studies had limited information on policy responses to address water scarcity in Thailand.

Myrthe Leijnse, Utrecht University

“Water scarcity doesn’t always look like a lake or river drying up in an arid climate, but can also manifest itself in wetter climates as temporarily low streamflow or falling groundwater levels. It has many diverse, complex drivers, whether that’s producing water-intensive crops or goods for global trade, rapid population growth, or inefficient use of water in our towns and cities,” said Marc Bierkens, National Geographic Explorer and professor of hydrology at Utrecht University.

Niko Wanders, project lead and associate professor of hydrological extremes at Utrecht University, adds, “by zooming in on these hotspots, we can understand the development of water scarcity in a regional context. We hope these insights can help us find better targeted solutions to alleviate water scarcity. Also, by comparing drivers and solutions between hotspots, we hope to equip policymakers with insights to help close the water gap.”

The Society’s World Freshwater Initiative supports grantees in science, conservation, education, and storytelling, who are illuminating water scarcity issues – as well as sustainable solutions – in these hotspot areas and beyond.

“The identification of these 21 water scarcity hotspots is a critical addition to our understanding of global water and how people, wildlife, and nature use it. A complement to the World Water Map, the hotspots help tell the story of our irreplaceable freshwater resource and are part of our ongoing commitment to illuminate and protect the wonder of our world,” said Alex Tait, The Geographer at the National Geographic Society. “This study embodies the power of the geographic approach: observe the world around us, gather and analyze data, and generate powerful insights about how people interact with water.”

Myrthe Leijnse, Utrecht University

CLICK HERE FOR MORE INFORMATION

https://news.nationalgeographic.org/new-study-21-global-water-scarcity-hotspots-identified-classified-into-7-hotspot-clusters-with-shared-water-challenges/?

Study shows health benefits of tackling arsenic, chromium-6 and other pollutants at once

WASHINGTON – Drinking water treatment that pursues a multi-contaminant approach, tackling several pollutants at once, could prevent more than 50,000 lifetime cancer cases in the U.S., finds a new peer-reviewed study by the Environmental Working Group.

The finding challenges the merits of regulating one tap water contaminant at a time, the long-standing practice of states and the federal government. 

In the paper, published in the journal Environmental Research, EWG scientists analyzed more than a decade of data from over 17,000 community water systems. They found that two cancer-causing chemicals – arsenic and hexavalent chromium, or chromium-6 – often appear together in systems and can be treated using the same technologies. 

If water systems with chromium-6 contamination also reduce arsenic levels to a range from 27% to 42%, it could avoid up to quadruple the number of cancer cases compared to just lowering chromium-6 levels alone, the study finds. 

Treatment of drinking water for one contaminant, such as nitrate, has advantages for public health. But tackling multiple contaminants at once increases the health benefits. And those benefits can expand along with the number of pollutants treated at the same time. 

 “Drinking water is contaminated mostly in mixtures, but our regulatory system still acts like they appear one at a time,” said Tasha Stoiber, Ph.D., a senior scientist at EWG and lead author of the study. “This research shows that treating multiple contaminants together could prevent tens of thousands of cancer cases.”

Chromium-6 and arsenic are commonly found in drinking water across the U.S. Chromium-6 has been found in drinking water served to 264 million Americans. 

“Addressing co-occurring contaminants is scientifically the most sound approach, as well as an efficient way to protect public health,” added Stoiber.

In California alone, nearly eight out of 10 preventable cancer cases are linked to arsenic exposure.

Arizona, California and Texas bear the highest burden of arsenic pollution and would gain the most from multi-contaminant water treatment efforts.

Health risks of water contaminants

Toxic chemicals like chromium-6, arsenic and nitrate pose the greatest risks to children, pregnant people and those living in smaller communities served by water systems relying on groundwater. Systems serving these populations often rely on only one water source and the smaller communities lack the resources to demand better treatment, despite facing the most serious health harms.

Chromium-6 

This cancer-causing chemical made infamous by the film “Erin Brockovich” is linked to serious health risks. Studies show even low levels in drinking water can increase the risk of stomach cancer, liver damage and reproductive harm. 

In 2008, the National Toxicology Program found much higher rates of stomach and intestinal tumors in lab animals exposed to chromium-6 in water. California researchers later confirmed a higher risk of stomach cancer in workers who had been exposed.

The Environmental Protection Agency does not limit the amount of chromium-6 in drinking water. It does regulate total chromium, which includes chromium-6 and the mostly harmless chromium-3. Total chromium is set at 100 parts per billion, or ppb, for drinking water.

Arsenic

Arsenic is found in drinking water in all 50 states. It occurs in natural deposits and as a result of human activities such as mining and pesticide use. Long-term exposure is linked to serious health issues, including bladder, lung and skin cancers, as well as cardiovascular and developmental harm.

The legal federal limit for arsenic in drinking water is 10 ppb, set in 2001 based on outdated cost estimates for treatment, not on what’s safest for health. California’s public health goal is just 0.004 ppb, the level scientists say would pose no significant cancer risk over a lifetime.

Arsenic can also contaminate certain foods, especially rice and rice-based products, making clean water standards all the more important for reducing overall exposure.

Nitrate 

Nitrate is one of the most common drinking water contaminants, especially downstream from agricultural areas where it enters water supplies through fertilizer and manure runoff. It’s also found in private wells, often near farms or septic systems.

Exposure to nitrate in drinking water is linked to serious health risks, including colorectal and ovarian cancer, very preterm birth, low birth weight, and neural tube defects. 

The EPA set the nitrate limit at 10 parts per million in 1992 to prevent “blue baby syndrome.” But it hasn’t updated the standard in over 30 years. New research shows cancer and birth-related harms can occur at levels far below the legal limit. European studies have found increased cancer risks at nitrate levels more than 10 times lower than the EPA limit.

“Ensuring clean drinking water for all communities is about fairness and equity,” said Sydney Evans, MPH, EWG senior science analyst and a co-author of the new study. 

“Communities in the U.S. that rely on groundwater are often affected by these contaminants. New water treatment technologies offer a chance to improve water quality overall. This strengthens the case for action and investment.”

Call for smarter water rules

Federal regulations still evaluate the cost and benefit of water treatment on a one-contaminant basis, a model EWG’s report calls outdated and inefficient. 

Small and rural water systems often face the steepest per-person costs to implement new treatment technologies. But they’re among the most exposed to pollutants and associated risks.

These systems frequently lack the funding and technical support to upgrade aging infrastructure, leaving residents exposed to serious health threats. This level of vulnerability calls for new strategies for these communities – a  boost in funding coupled with more effective regulations.

For example, nitrate, often found alongside chromium-6 in drinking water, represents a major but overlooked opportunity for health protection.

“Nitrate pollution is a public health crisis, particularly in the Midwest but also across the country,” said Anne Schechinger, EWG’s Midwest director. “The federal nitrate limit was set decades ago to prevent infant deaths, but we now know see cancer and birth complications at levels of nitrate far below that outdated standard.

“Even lowering nitrate slightly could prevent hundreds of cancer cases and save tens of millions of dollars in health care costs, especially when paired with treatment for other contaminants, such as chromium-6 and arsenic,” she said. “There’s a real cost to inaction – our health and our wallets can’t afford to wait for better treatment.”

Proven technologies like ion exchange and reverse osmosis, already used today, can remove nitrate, chromium-6 and arsenic from drinking water at the same time. 

“This is about more than clean water – it’s about protecting health and advancing equity,” said David Andrews, Ph.D., acting chief science officer at EWG. “We have the engineering solutions to fix the broken drinking water system in the U.S., but we need state and federal policies to reflect the reality people face when they turn on the tap.”

Consumers concerned about chemicals in their tap water can install a water filter to help reduce their exposure to contaminants. The home filter system that’s most effective for removing chromium-6, arsenic and nitrate from water is reverse osmosis. Ion exchange technology is another option for reducing levels of these contaminants.

EWG’s water filter guide contains more information about available options. It is crucial to change water filters on time. Old filters aren’t safe, since they harbor bacteria and let contaminants through.

People can also search EWG’s national Tap Water Database to learn which contaminants are detected in their tap water.

CLICK HERE FOR MORE INFORMATION

https://www.ewg.org/news-insights/news-release/2025/07/ewg-reducing-multiple-tap-water-contaminants-may-prevent-over?