A new global analysis suggests that the sodium in drinking water could be an overlooked contributor to high blood pressure.
The study, published in BMJ Global Health, reports that higher salinity in drinking water is associated with higher blood pressure and an increased risk of hypertension. Researchers say the findings should expand how public health officials think about blood pressure prevention, especially in regions where groundwater supplies are vulnerable to saltwater intrusion.
The research was led by investigators from Florida International University (FIU), including Rajiv Chowdhury, in collaboration with teams from Johns Hopkins University, Vanderbilt University, and the Pan American Health Organization.
“This is not about alarming people,” Chowdhury said, emphasizing that the goal is to highlight an environmental factor that may be influencing blood pressure in certain communities. He noted that in many countries, including the United States, people already consume more sodium than recommended through diet, and salty drinking sources could further increase overall intake without people realizing it.
To reach their conclusions, researchers conducted a systematic review and meta-analysis of 27 population studies covering more than 74,000 participants from the United States, Bangladesh, Vietnam, Kenya, Australia, Israel, and several European countries.
Across the pooled data, people exposed to higher salinity drinking water had higher average systolic and diastolic blood pressure than those using lower-salinity sources. The analysis estimated systolic pressure was roughly 3.2 mm Hg higher, while diastolic pressure was about 2.8 mm Hg higher.
The study also found that higher drinking-water salinity was linked to a 26% greater risk of hypertension, with the most consistent and strongest connections observed in coastal populations.
While the blood pressure increases may appear small at an individual level, the researchers argue that even minor shifts can translate into significant public health consequences when millions of people are exposed. Chowdhury compared the scale of risk to other well-known contributors to hypertension, such as low physical activity.
Salt can enter drinking water through multiple pathways, but the researchers highlighted saltwater intrusion into groundwater as a major concern. Groundwater accounts for a large share of global drinking water supplies, and coastal areas are especially vulnerable because freshwater and seawater systems sit close together underground.
With more than three billion people living in coastal or near-coastal regions worldwide, the researchers said water salinity should be part of broader planning around health and infrastructure, particularly as water stress and environmental change increase pressure on freshwater resources.
The authors also pointed out that while dietary sodium is widely addressed in hypertension prevention guidance, sodium exposure through drinking water is rarely factored into mainstream recommendations, even though it may matter in certain locations.
The researchers said more work is needed to determine whether salty drinking water is linked to other long-term outcomes such as heart attacks and strokes, noting that evidence is currently insufficient to draw firm conclusions. Still, they argue the blood pressure signal is strong enough to warrant closer monitoring and future research.
Experts say the findings could influence how governments approach water quality management in coastal areas. Todd Crowl, director of FIU’s Institute of Environment, said the study adds useful context for policy and planning, particularly in places that rely heavily on groundwater and face growing risks of saltwater intrusion.
For individuals, the researchers stress that food remains the main source of sodium for most people, but in higher-salinity regions, drinking water may add to the total burden. They suggest practical steps such as checking local water quality reports where available and continuing to manage overall sodium intake, especially for those already monitoring blood pressure.