A study recently published in the science journal GeoHealth shows sodium and chloride levels in tap water peak during the late-season snowmelt.
Every year, more than 20 million metric tons of road salt are applied to roads and highways across the United States to help melt snow and ice that accumulate, with much of the salt making its way into rivers and streams that serve as a source of drinking water.
The study looked into the changes in amounts of sodium and chloride during the winter of 2018-2019 in the Philadelphia area, which relies primarily on local rivers for its drinking water.
Researchers said they found that when snow begins to melt heading into spring from winter, levels of sodium and chloride in tap water are at their highest.
That’s not good news for adults on low salt diets.
"This contribution of tap water sodium to the recommended daily sodium intake limits ingested by adults on low salt diets ranged from 4.2% to 33.3%," the study said.
It also showed almost all the tap water samples that had been collected were above the Environmental Protection Agency’s recommended guideline of 20 milligrams per liter.
Samples were collected weekly between Nov. 11, 2018 and March 31, 2019, from three single-family homes in southeastern Pennsylvania, with each being in a different municipality - Philadelphia, Havertown and Pottstown.
After samples were collected and research was completed, the study showed that the peak sodium and chloride levels in each location occurred from mid-January through the end of March, and coincided with a series of snowstorms in the area and upstream from the homes.
Peak levels were also discovered when temperatures were above freezing, allowing for snow and ice to melt.
The study says these findings show the need for more sampling to be completed during the winter for sodium levels, as well as better communication between water companies and the public regarding the risk of increased sodium levels in tap water during winter months.