Connecticut Department of Energy & Environmental Protection

Road Salt Frequently Asked Questions

What are sources of salt to the environment?

Salt is introduced into the environment by various human activities including: deicing road salt applications by state, local, and private contractors, deicing salts to walkways and driveways by private contractors and residents, urban runoff (i.e. degradation of concrete infrastructure), fertilizers, sewage, and food waste.

Salts are also used in ion exchange units (aka water softeners) to remove naturally occurring minerals and other elements from drinking water. Ion exchange units use either sodium chloride (NaCl) or potassium chloride (KCl) to remove unwanted substances before the water cycles through household plumbing. A waste product of ion exchange units is a concentrated brine backwash, which contains high levels of salt. The brine backwash is discharged from the home and is introduced to the environment. If a well is near the brine backwash discharge location, it can potentially introduce salt into the drinking water.

It is important that well users understand that using an ion exchange unit will add either salt to the treated water.

What are the chemicals that are being applied to the roads, parking lots, sidewalks, and driveways?

Rock salt, sodium chloride (NaCl), is the most common salt used in Connecticut for the removal of snow and ice.  NaCl is effective for the removal of snow and ice down to 15-20°F.  In order to make NaCl more effective, sometimes other salts such as magnesium chloride (MgCl2) or calcium chloride (CaCl2) are added to the NaCl.  This enhances the effectiveness of NaCl because MgCl2 is effective at removing snow and ice down to 5°F and CaCl2 is effective to -10°F.

Salts used for winter maintenance can be applied as either a solid (rock salt) or dissolved in water forming a brine. Brine can be applied to surfaces before a storm or applied to the solid materials being spread on the roadways, parking lots, or sidewalks to enhance their performance.  When brines are applied to pavement before a winter storm, they help to prevent the snow and ice from bonding to the pavement surface, make plowing more effective, and reduce the amount of salt required throughout the storm.  When brine is applied to the solid materials (pre-wetted salts), it provides water to the solid salt which leads to a faster reaction time and less total salt is needed. There are optimal concentrations for the amount of salt (NaCl, MgCl2 or CaCl2) in the brine to maximize their effectiveness and minimize the overall amount of salt required.

What are the potential health impacts?

Both sodium and chloride have the potential to cause direct, or indirect, impacts to human health and to the environment.

Sodium levels in drinking water exceeding 100 mg/L can make a substantial contribution to dietary sodium for those on a sodium-restricted diet. Anyone in the household on a medically ordered sodium-restricted diet should speak with their physician about the sodium concentration in their well water when it exceeds 100 mg/L.

Chlorides do not present a direct health risk to humans, but elevated chlorides (>250 mg/L) increase the corrosivity of water, which can leach harmful metals (such as lead, copper, and manganese) from household plumbing and soils into the water. Exposure to these metals can present significant health risks. The increased corrosivity of the water also causes damage to household plumbing and appliances.

For further information on sodium and chloride in private drinking water wells, please review the DPH Fact Sheet: Sodium and Chloride in Well Water.

What are the environmental impacts?

Elevated sodium concentrations can strip essential nutrients from the soil that are necessary for plant growth. This can be observed along roadways where vegetation appears “burned” or stressed. Sodium can also impact freshwater aquatic organisms.

Under the Clean Water Act, the US Environmental Protection Agency (EPA) has set a surface water quality standard for chloride at 230 mg/L.

How can salt impacts be minimized?

The main way to minimize salt impacts is to use less salt in all applications.  Reducing the amount of salt used on roadways, parking lots, sidewalks, and driveways while still maintaining public safety, and decreasing frequency of ion exchange backwash discharges can dramatically reduce the salt load to the environment and diminish the risk of impact to groundwater.

Residents who own wells are their own water system managers, therefore, they should carefully consider what treatments options are necessary based on their water quality. It is important to evaluate if salt-based technology, such as ion exchange (aka, water softener), is necessary, as eliminating the use of, or upgrading to efficient technology, will lessen unnecessary salt discharges to the environment. Other northern states, such as Wisconsin and Minnesota, have demonstrated proper maintenance or upgrading of ion exchange systems can significantly reduce salt discharges to the environment and save money for the homeowners.

If well owners have further questions regarding treatment options for their well water, they should contact water treatment professionals licensed with the Department of Consumer Protection and review the DPH Private Well Program website for further information including the DPH Fact Sheets: Publication #19 Questions to Ask when Purchasing Water Treatment Equipment for Your Home and Publication #29 Hardwater-Softeners Facts and Issues. Private well owners should reach out to their Local Health Department for further information on proper backwash discharge.

Other states, including New Hampshire, Minnesota, and Wisconsin, have funded chloride reduction programs that conduct public outreach to educate municipalities and private applicators on winter maintenance best management practices that reduce chloride use while maintaining public safety. To learn more about the best practices for salt application and maintenance of facilities and equipment, winter maintenance professionals (state, municipal, or private snow removal contractors) can attend a CT Green Snow Pro class offered by the CT Training and Technical Assistance (T2) Center. Dr. Michael Dietz, UConn Center for Land Use Education and Research (CLEAR), demonstrated that salt applications could be successfully reduced while maintaining the same level of public safety.

I have a water softener that uses sodium chloride, will it help if I change to potassium chloride?

Both sodium chloride (NaCl) and potassium chloride (KCl) are “salts”. When these materials dissolve in water they break up into Na, or K, and Cl ions that sit in the water. While using KCl may decrease the amount of Na in your treated drinking water, the backwash for the treatment system will be flushed with a salt and discharge a brine solution out of the home. Improving the efficiency of your treatment system through regular maintenance and/or upgrading to efficient technology is the best way to minimize salt discharge from your home.

What information can municipalities provide to assist DEEP with salt-related investigations?

If the impacted private well is on a property that abuts a Town road, then DEEP will coordinate with the respective municipality and Local Health Department to discuss the complaint and potential sources of salt. DEEP Remediation staff may send a questionnaire to the Department of Public Works to collect information regarding snow and ice management Best Management Practices.

What resources are available to winter maintenance professionals and Municipalities addressing salt-impacted wells?

For Best Practices of Salt Application

The CT T2 Center has provided CT Green Snow Pro training to support best practices and sustainable winter operations to state and municipal applicators since 2018. This training program was expanded in 2022 (Public Act No. 22-118) with the development of a class to meet the needs of private commercial applicators. There are two classes available depending on whether the applicator maintains roads (CT Green Snow Pro for Roadways) or parking lots and sidewalks (CT Green Snow Pro for Parking Lots and Sidewalks). While these classes are voluntary, it is highly recommended that all winter maintenance professionals enroll in the training. Using less salt not only benefits the environment but may also positively impact salt budgets/expenditures and operational efficiency.

For Evaluating and Implementing Remedial options

DEEP can provide knowledge of salt geochemistry, hydrogeology, and geology to assist Municipalities in evaluating source(s) of salt related to impact. Together, DEEP and DPH can provide technical assistance, or health-based assistance, when evaluating the source(s) of contamination and potential remedial options.

The plumbing and appliances have been damaged in my home due to corrosion. Can DEEP assist me with reparations for damages?

No. DEEP’s purview under CGS §22a-471 is limited to protecting the quality of the groundwaters of the State and identifying Responsible Parties whose activities have caused pollution to the groundwater that will reasonably create a risk to human health and the environment. DEEP’s jurisdiction does not extend to damages to property.

If private well owners wish to press for damage reparations, they will need to file a claim against the identified Responsible Party(ies) for polluting the groundwaters of the State that resulted in excessively corrosive water that damaged private property.

What remedial actions can be used to address salt contamination in a private well?

Installation of a new well

The CT Department of Transportation (DOT) has experienced success with replacing approximately two dozen impacted private wells with deeper wells (at least 350 feet deep) with at least 60 feet of steel casing into bedrock. DEEP has worked with other municipalities who have also had success installing similarly constructed wells.

While drilling deeper wells and installing deeper casings is a possible option, this option does not guarantee they will provide clean drinking water; it is impossible to know the chloride concentration in the deep groundwater aquifer until drilling has taken place.

Whole-house Reverse Osmosis (RO) treatment system

Using a whole-house RO system is a significant investment that requires using significant water volume, produces and discharges significant volumes of wastewater, and requires regular maintenance.  Whole-house RO systems produce large volumes of wastewater. Most whole-house RO systems send three to four gallons of water to waste for every one gallon of treated water produced. The wastewater would contain contaminants removed from the water (including salt, metals, minerals, etc.) and would need to be discharged, thereby discharging the pollutants back into the environment and continuing the pollution cycle. This volume of wastewater cannot discharge to septic systems and requires installation of a dedicated water treatment wastewater subsurface dispersal system for each whole-house RO system installed. There are requirements on where a dispersal system can be located on a property pursuant to the DPH 2023 Technical Standards for Subsurface Sewage Disposal Systems.

Connection to public water service

Where available, connecting to public water can provide a long-term source of drinking water. However, recent data shared by the CT Department of Public Health has demonstrated even some public water supplies are being impacted by chloride. Additionally, in rural areas, where public water is not readily available, extension of a public water main can be cost prohibitive.

Why not switch back to sand and salt?

In July 2015, a report titled “Winter Highway Maintenance Operations: Connecticut” was prepared for the CT DOT by the Connecticut Academy of Science and Engineering (commonly referred to as the CASE study). The CASE study concluded the use of abrasives, such as sand, only provide temporary traction assistance until they are removed from surfaces during plowing activities or until the sand is kicked out of the wheel paths by traffic. It does not take very many vehicles to kick the sand out of the wheel paths and render the sand worthless. In addition, tires grinding on the sand tend to round off the particles which greatly reduces its effectiveness.. Unlike salt, the properties of sand does not melt snow or and requires the addition of salt to prevent the sand from freezing so it can be spread. Lastly, research has demonstrated that sand binds heavy metals (such as chrome, zinc, nickel, etc.) and other petroleum-based contaminants, so the material will become polluted throughout the winter season. Once the sand is polluted it needs to be disposed of properly to ensure the safety of human health and environment.

The CASE study estimated more than 50% of abrasives applied to the road are not recovered following the winter season. The excess abrasives remaining in the environment negatively impacts air quality (i.e., dust) and added costs for sweeping, removal, and disposal of the polluted sand by both municipalities and the state DOT. The DOT shifted from using sand/salt mixes to only salt in 2006 for winter maintenance operations to minimize these impacts. It was noted in the CASE study that other northern region states across the US were also transitioning away from sand/salt mixtures at the same time the CT DOT transitioned.

Learn More about Road Salt:

Potable Water Program - Salt Investigations