Salty Drinking Water Linked to High Blood Pressure?

For most people, salt is something to watch on their plate, not in their tap. But a global analysis suggests that drinking water itself could be an overlooked source of sodium and one that may quietly raise blood pressure for millions of people worldwide.

Published in BMJ Global Health, the study found that higher salinity in drinking water was associated with higher blood pressure and a greater risk of hypertension, especially among people living in coastal regions

The work was led by FIU researchers, including Rajiv Chowdhury, chair of the Department of Global Health at FIU's Robert Stempel College of Public Health & Social Work, in collaboration with investigators from Johns Hopkins University, Vanderbilt University, and the Pan American Health Organization.

"This is not about alarming people," Chowdhury said. "It's about recognizing an environmental factor that may be contributing to high blood pressure in some communities and making sure it's part of the public health conversation. In the U.S., most people already consume more sodium than recommended, so additional sodium from saltier drinking sources may only add to overall intake."

The researchers conducted a systematic review and meta-analysis of data from 27 population studies involving more than 74,000 participants across the United States, Bangladesh, Vietnam, Kenya, Australia, Israel, and several European nations.

They found that people exposed to higher salinity in their drinking water had, on average, higher systolic and diastolic blood pressure than those exposed to lower salinity. Specifically, systolic blood pressure was about 3.2 mm Hg higher, while diastolic blood pressure was nearly 2.8 mm Hg higher.

Higher drinking water salinity was also associated with a 26% increased risk of hypertension, with the strongest and most consistent associations observed in coastal populations.

"These are modest increases at the individual level," Chowdhury said, "but when large populations are exposed, even small shifts in blood pressure can have significant public health effects. To put it in perspective, the risk level observed in this study for water salinity is like other established cardiovascular risk factors, such as low physical activity, which increases hypertension risk by approximately 15–25%."

Salt can enter drinking water through several pathways, including saltwater intrusion into groundwater – which makes up nearly half of the world's drinking water supply. These conditions are most often seen in coastal regions, where freshwater and saltwater systems sit close together underground.

More than three billion people worldwide live in coastal or near-coastal areas, a figure the researchers highlight as part of the study's public health context. In many of these regions, groundwater is a primary drinking source, making salinity an important factor in overall quality.

While dietary sodium intake has long been recognized as a risk factor for high blood pressure, sodium from drinking water, especially for those living in coastal areas, is not currently considered in most hypertension prevention guidelines.

"Our findings suggest that environmental exposures, such as drinking water salinity, deserve more attention alongside traditional behavioral risk factors," Chowdhury said.

While the analysis found consistent links between drinking water salinity, elevated blood pressure, and hypertension risk, the researchers found insufficient evidence to draw conclusions about other cardiovascular outcomes, such as heart attack or stroke. "This is a major unmet scientific area, and our meta-analysis should inform future studies that will include wider chronic disease outcomes", Chowdhury said.

The findings raise important questions for public health planning, particularly in coastal areas where drinking water salinity is expected to be higher.

Monitoring water quality, improving water management strategies, and considering environmental factors in hypertension prevention efforts could help reduce long-term cardiovascular risk.

"South Florida as well as many other coastal regions globally rely heavily on groundwater for drinking, which makes salinity an important and often overlooked factor in water quality," said Todd Crowl, director of FIU's Institute of Environment, who was not involved in the study. "By linking drinking water salinity to blood pressure risk, this study provides useful context for future water management and public health decisions and provides even more focus on the importance of protecting our groundwater resources. For South Florida, this puts even more importance on Everglades restoration which ultimately will protect our freshwater from further saltwater intrusion."

Taken together, the findings underscore the importance of looking beyond individual behaviors when addressing high blood pressure risk. By highlighting drinking water salinity as a potential contributor, the research points to water quality as a factor that intersects with both public health and long-term planning in coastal regions.

"Food remains the primary source of sodium for most people," Chowdhury said. "But where salinity is elevated, drinking sources may add to total intake. Checking local water quality reports if available and focusing on overall dietary sodium are practical steps, particularly for individuals who need to manage blood pressure."