It’s like salt in a wound.
Global warming has been blamed for stronger and more frequent storms, droughts, floods and rare disease outbreaks. Now, it might be fueling kitchen table health crises, too.
Researchers are concerned that rising sea levels are contaminating fresh drinking water with seawater — and that the extra salt could have the same effect on blood pressure as key risk factors like inactivity.
A recent analysis of data on water salinity and global human health outcomes revealed a bitter pattern: People who drank saltier water, most often in coastal communities, had higher systolic and diastolic blood pressure on average and were 26% more likely to develop hypertension, or chronic high blood pressure that can lead to major cardiac events.
The increases in blood pressure were “modest,” per the report, as food remains most people’s main source of sodium.
But compared to other cardiovascular risk factors like physical inactivity — which increases risk of hypertension by anywhere from 15% to 25% — salty drinking water emerges as a significant concern.
Especially for the more than 3 billion people who live close to a coast worldwide.
Coastal geologist Robert Young told The Post that the increasing volume of the ocean — what we call sea level rise — also “raises coastal groundwater everywhere.”
Groundwater runs downhill, but when shorelines are eroded by rising seas, there’s no more slope. What you get is a slosh of sea- and groundwater — like you’re “backing up the plumbing.”
Young, who is also the director of the Program for the Study of Developed Shorelines at Western Carolina University, said that in some places, the saltwater infiltrates the freshwater groundwater that we drink.
The salinity of your drinking water depends heavily on where it comes from.
Dr. Rajiv Chowdhury, professor and chair of Global Health at Florida International University, told The Post that water salinity is especially concerning for coastal dwellers in low- and middle-income countries who are “generally more vulnerable for their reliance on shallow wells or groundwater as main drinking sources.”
Compared to wealthier regions like the US, they may also have fewer resources for water-quality monitoring, contamination mitigation or water treatment plant relocation.
But plenty of Americans are vulnerable to these changes, too. Chowdhury, an author of the new study, said parts of the Gulf Coast and coastal Louisiana are particularly at risk, as is South Florida, which is reliant on the Everglades — one of the best-documented cases of saltwater intrusion in this country — for its drinking water.
Outside of those regions, “the real concern [right now] is typically individual wells,” Young said. “People on their own well water have less control of all of this than municipal water,” which has to meet relatively strict guidelines and is subject to routine testing.
“When we start to see municipal water treatment facilities getting an uptick in salinity […] that should be flashing red lights for every place else.”
Dr. Robert Young, coastal geologist
For that reason, saltier water “can cause problems” for cities that might soon have to invest in treatment facility updates to handle the salinity.
Drinking water has been under the microscope a lot lately, with increased pressure from Make America Healthy Again advocates to remove toxins that are known to be widespread.
Compared to more “ubiquitous” issues like PFAS and microplastics, Young said that water salinity — given that, “at the moment at least,” it’s mostly only relevant to low-lying coastal populations — isn’t at the top of the fix-it list.
But that’s exactly why now is the right time to put contingency plans in place.
If sea levels continue to rise at the rate scientists expect — 7.2 feet by the year 2100 — water salinity and potential cardiovascular risk will also continue to climb. And not just down South.
Just a few feet of sea level rise will not only leach saltwater into the ground, but it will also push it into rivers and estuaries. The current infrastructure used to process river water for local taps wouldn’t cut it.
“Those water treatment facilities are not set up to handle saltwater. They’re set up to make freshwater drinkable, but saltwater is a whole other can of worms,” Young said. “You don’t want to be running salt water through all of your equipment; it’s corrosive.”
Desalinating water and constructing reverse osmosis plants are two “energy-intensive and expensive ways to make freshwater.” A solution that’s been proposed in vulnerable countries like Bangladesh is known as managed aquifer recharge, or the underground storage of reclaimed freshwater for later use.
Hypertension is already of urgent concern in the US, where, in 2023, it contributed to an estimated 664,470 deaths.
To balance out a sodium spike in the water, Chowdhury recommends a hypertension protocol: Cutting down on salty foods, eating potassium-rich fruits and vegetables and regularly monitoring blood pressure.
Though salty drinking water is not yet a widespread issue in the US, Young said that rising seas will eventually force our hand, especially given the public health threats that are surfacing.
We have the choice to act before it really starts to sting.
“When we start to see municipal water treatment facilities getting an uptick in salinity […] that should be flashing red lights for every place else,” he said.
“I’m not terribly optimistic that we’re gonna do too much about it until it becomes a real expensive problem for somebody. Then maybe we’ll pay attention.”
