Drinking water is getting saltier. How does that affect humans?

In the United States and across the world, research shows that groundwater is becoming saltier. Higher levels of salts in water may be harmful to people, reducing kidney function and increasing blood pressure. A new study will provide an opportunity to examine the impact of drinking water salinity on human health over time.  

A group of researchers led by Asher Rosinger, associate professor of biobehavioral health at Penn State and leader of the College of Health and Human Development’s Environmental-Health-Sciences Program Area, will expand an ongoing longitudinal study to investigate the effects of drinking water salinity, thanks to a new five-year grant from the National Institute of Environmental Health Sciences. 

The researchers will seek to understand how variation in drinking water salinity — due to naturally-occurring salts and exposure to newly constructed water sources that create variation in both lower and higher salinity levels — affects kidney function and injury, blood pressure over time, and whether these blood pressure changes affect kidney health. In addition, they will examine the impact of seasonal drinking water salinity on people’s hydration and water security.  

“More and more people will become affected by drinking water salinity over time, and — given the fact that regular filtration and treatment options do not remove salt from water — we need to better understand the health effects of drinking water salinity,” Rosinger said. “This setting, which has naturally-occurring variation in salinity levels, provides an important opportunity to study the effects of water salinity — and the types of salts — on hypertension and kidney disease.”  

The researchers will build on their ongoing longitudinal study to examine 600 adults, but Rosinger said that results of the study have implications for people across the world. Globally, the number of people with hypertension—high blood pressure—is increasing. Hypertension is the leading risk factor of death from cardiovascular disease and chronic kidney disease, contributing to 10.4 million deaths annually.  

“Salt intake is a key risk factor for hypertension and chronic kidney disease. Yet, drinking water is overlooked as a source of salt,” Rosinger explained. “Less is known about the effect of water salinity on kidney function or how elevated blood pressure may work in concert with salinity to impair kidney function. This study will help us understand how much it matters when saltwater enters our drinking water — either from saltwater intrusion or other ways like salting roads in the winter. Critically, there are not health-based water standards for sodium and chloride, which this research will help build toward.” 

W. Larry Kenney and Michael Hunter of the Penn State College of Health and Human Development, Herman Pontzer of the Department of Evolutionary Anthropology at Duke University, Dr. Jeff Sands of Emory University School of Medicine, William Farquhar of the Department of Kinesiology & Applied Physiology at University of Delaware, Emmanuel Ndiema of the National Museums of Kenya, and Rosemary Nzunza at the Kenya Medical Research Institute are contributing to this research. 

Originally published in March 2025