Road Salt – Sodium Chloride

Intersection of Roads and Drinking Water
Opportunities for Collaboration Between State Programs

Intersection of Roads and Drinking Water:  The table below provides opportunities for “intersection” between roads and drinking water.  Together, state highway and state drinking water programs can:

  • Share maps, water quality data, and information on roads and delineated drinking water protection areas (for both surface and ground water).
  • Provide information about and leverage potential funding sources.
  • Assist with implementation and help target state DOT initiatives for protecting drinking water.

Partner to share information among states, and conduct outreach to municipalities.

Intersection of Roads and Drinking Water

State Highway Programs State Drinking Water Programs
Map Overlays Roads Drinking water protection areas
Development/Planning Road construction/design
Stormwater Runoff
Land use protection/conservation
to prevent contamination
Best Practices Road maintenance, salt storage,
calibrated de-icing application
Remediation and mitigation actions to address potential contaminants
Spills/Emergency Response Planning/Exercises Notification, response, containment, and environmental cleanup Monitoring/early warning systems shutoff/treatment/decontamination

Road Salt and Drinking Water:  In the U.S., an average of more than 20 million tons of road salt are applied to roads, parking lots, sidewalks and driveways each year. Studies have shown that road and parking lot de-icing applications have in some cases doubled chloride concentrations in streams and have negatively impacted shallow aquifers used for drinking water. The following table provides information about impacts from road salt based on each element of the multiple barrier approach to ensure safe drinking water.

Multi-Barrier Approach to Ensure Safe Drinking Water from Source to Tap Road Salt Impacts on Drinking Water
Protection from contamination (from chloride, sodium, and additives in road salt and de-icing) Surface water: Alkaline rivers and mobilization of contaminants from soils and sediments.
Drinking water treatment Ground water: Mobilization of arsenic and other natural contaminants in aquifers.
Distribution system delivery High treatment costs for reverse osmosis, distillation, or de-ionization and for disinfection by-products.
Community Involvement Working with (transportation) partners and the public to reduce and tailor the use of salt and de-icing applications.

Drinking water health advisory and standards for chloride, sodium, and ferrocyanide (additive):  There are currently no federal regulatory requirements for maximum contaminant levels of sodium or chloride under the Safe Drinking Water Act for finished water.  However, EPA has established:

  • A health advisory level of 20mg/L for people on salt restricted diets.
  • A secondary (aesthetic) drinking water standard of 250 mg/L for chloride ions and 250 mg/L for sulfate ions, for salty taste.

In addition, EPA added ferrocyanide (a road salt additive) to its list of toxic pollutants under section 307(a) of the Clean Water Act in 2003.

Additional Resources

For more information about road salt and drinking water, please follow the links to the state resource documents and examples, and USGS research study.

  • New Hampshire Environmental Fact Sheets on: Sodium and Chloride in Drinking Water  includes health implications, control, and drinking water treatment considerations; and Road Salt and Water Quality includes best practices for road salt application and storage.
  • Connecticut Bridge Manual and Notification Letters: The Connecticut DOT Local Bridge Manual requires coordination with, and notification of the water utility and Department of Public Health for “work…in or adjacent to…a public drinking water source” (sec. 4.3.1.8, p. 30, 2nd bullet).

USGS Study:  Increasing chloride in rivers of the conterminous U.S. and linkages to potential corrosivity and lead action level exceedances in drinking water

 

To learn more about how you can start coordinating with state drinking water programs on roads and road salt, contact Deirdre Mason of ASDWA at dmason@asdwa.org