Rock Salt Runoff Threatens Philadelphia Drinking Water

Melting snow could introduce high levels of sodium chloride into the city's water supply.

Published on Feb. 12, 2026

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As piles of snow and ice covering the Philadelphia region begin to melt, research shows the rock salt used for de-icing can end up in the drinking water supply, raising concerns for people on salt-restricted diets. Experts say the salt levels in local waterways have been doubling about every 20 years, and a drinking water supply could have 10 to 30 times the normal amount of sodium chloride.

Why it matters

Excess salt in drinking water can be hazardous for people in high-risk groups, causing the body to retain water, increasing blood volume, and straining the kidneys. This can lead to higher blood pressure and added cardiovascular risk.

The details

Rock salt used on roads and sidewalks is sodium chloride, the same as table salt. As the snow melts, this salt runs off into the Schuylkill and Delaware rivers, the main sources of drinking water for the Philadelphia region. The Philadelphia Water Department is monitoring mineral levels to ensure the water meets regulations, but consumers may notice a slightly salty taste for a few days.

  • As piles of snow and ice covering the Philadelphia region begin to melt.

The players

John Jackson

A senior scientist at Stroud Water Research Center, an independent nonprofit in Chester County.

Dr. Arthur Frank

An environmental health expert at Drexel University.

Philadelphia Water Department

The largest provider of drinking water in the Philadelphia region.

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What they’re saying

“Salt in the waterways has been doubling about every 20 years.”

— John Jackson, senior scientist

“It's especially hazardous for people in high-risk groups, but excess salt is a potential danger for everyone.”

— Dr. Arthur Frank, environmental health expert

“It's the sodium that's causing the difficulty with the strain on the kidneys. Raising blood pressure, ultimately adding to cardiovascular risk.”

— Dr. Arthur Frank, environmental health expert

What’s next

The Philadelphia Water Department says it is monitoring mineral levels to ensure the city's drinking water meets federal and state regulations.

The takeaway

This issue highlights the need for better management of road salt use and runoff to protect public health, especially for vulnerable populations on salt-restricted diets. Consumers may need to consider water filters or bottled water if they are concerned about elevated sodium levels in their drinking water.