Salt is one of the most abundant minerals on Earth, and by most measures, it’s a sustainable resource. The oceans alone hold enough dissolved sodium chloride to supply human needs for millions of years, and geological processes continuously recycle salt through erosion, sedimentation, and tectonic activity. But “sustainable” isn’t just about running out. The ways we extract, use, and dispose of salt carry real environmental costs that complicate the picture.
Salt as a Resource: Renewable or Not?
Salt occupies an unusual category. It’s technically a mineral, which normally makes it non-renewable. But unlike copper or lithium, salt is constantly being recycled by the planet. Sodium chloride collects in sedimentary layers on the ocean floor. Over geological time, plate tectonics pushes those layers under continental masses at subduction zones, and the trapped salts eventually make their way back to the surface through leaching, then wash back into the sea. The salinity of the oceans has remained stable for millions of years because of this cycle.
From a supply standpoint, salt is effectively inexhaustible. Global reserves are enormous, and seawater provides a virtually limitless source. The sustainability question isn’t whether we’ll run out. It’s whether our methods of getting it and using it cause lasting harm.
How Salt Is Produced
Salt production falls into four main categories, each with a different environmental footprint. According to the U.S. Geological Survey’s 2024 data, rock salt accounts for 46% of salt sold or used in the United States, salt in brine makes up 33%, vacuum pan salt 11%, and solar evaporation salt 10%.
Rock salt mining works like any conventional mining operation: cutting or blasting salt from underground deposits. It requires heavy machinery and significant energy. Salt in brine is extracted by pumping water into underground salt deposits, dissolving the salt, and bringing the brine to the surface for processing. Vacuum pan salt refines that brine further using heat and evaporation under controlled pressure. Solar salt, the lowest-energy option, relies on sunlight and wind to evaporate seawater or brine in large shallow ponds.
Solar evaporation is the most energy-efficient method by far, but it requires large tracts of coastal land and the right climate. Rock salt mining dominates because underground deposits are widespread and the salt can be extracted year-round regardless of weather.
Environmental Costs of Mining
Underground salt mining can cause serious, lasting damage to the landscape. The collapse of the Retsof Salt Mine in New York, documented by the USGS, illustrates the worst-case scenario. The roof collapse formed sinkholes, caused widespread land subsidence, cracked and shifted structures on the surface, and changed stream flow and erosion patterns in the area. Flooding of the mine drained overlying aquifers, altered groundwater salinity (rendering domestic wells unusable), and even allowed naturally occurring gas to enter homes through water wells.
Salt’s extreme solubility in water makes these problems self-reinforcing. Whenever water begins flowing into a salt mine, it dissolves the surrounding salt, widening the channels and accelerating the process. This can destabilize overlying rock layers, leading to sagging, collapse, and new pathways for water leakage to the surface. Not every mine fails this way, but the risk is inherent to the geology.
Solution mining (pumping water underground to dissolve salt) carries similar subsidence risks, though the surface disruption is generally smaller than conventional mining. Both methods can contaminate freshwater aquifers with high-salinity water if containment fails.
The Road Salt Problem
A large share of the salt produced each year gets spread on roads in winter. This is arguably the least sustainable use of salt. Once applied, road salt dissolves in meltwater and runs off into streams, lakes, soil, and groundwater. Chloride doesn’t break down or get filtered out naturally. It accumulates. Many freshwater lakes and streams in northern regions have shown steadily rising chloride levels over decades, and elevated salinity is toxic to freshwater fish, amphibians, and aquatic plants. It also corrodes infrastructure, from bridges to underground pipes, creating billions of dollars in maintenance costs.
This isn’t a supply problem. It’s a pollution problem. The salt itself is cheap and abundant, but the environmental damage from spreading millions of tons of it across landscapes every winter is one of the biggest sustainability concerns associated with salt.
Microplastics in Commercial Salt
Ocean pollution has introduced a newer sustainability concern: microplastics in salt products. A study of commercial salts in Australia found microplastic contamination ranging from about 28 to 174 particles per kilogram, with an average of roughly 85 particles per kilogram across all types tested. Interestingly, sea salt didn’t have the highest contamination levels. Some processed salts, including Himalayan pink crystal and black salt, contained more microplastics than sea salt, likely picking up contamination during processing and packaging rather than from the ocean itself.
At typical daily salt intake (around 5 to 10 grams), the number of microplastic particles you’d consume from salt alone is very small compared to other dietary sources like bottled water or shellfish. But the presence of plastics in salt is a marker of broader ocean pollution, and it highlights how even a “natural” product can carry the consequences of environmental degradation.
Desalination Brine as a New Source
Desalination plants, which remove salt from seawater to produce drinking water, generate enormous volumes of concentrated brine as waste. Traditionally, this brine gets dumped back into the ocean, where it can harm marine ecosystems near discharge points. But researchers are increasingly looking at this waste stream as a resource.
Recent work published in Applied Catalysis B demonstrated a process that recovers valuable minerals from desalination brine while simultaneously capturing carbon dioxide. The process extracts magnesium and calcium ions, converting them into marketable compounds like calcium carbonate and magnesium hydroxide. Recovery rates reached up to 28% for magnesium and 64% for calcium, with about 40% of the recovered minerals existing in carbonate form, meaning they’ve locked away CO2 in the process. Energy consumption was roughly 30% lower than traditional extraction methods, and the researchers’ analysis suggests the process is both carbon-negative and profitable.
This approach turns a pollution problem into a supply chain. Instead of mining new salt and dumping brine waste, desalination facilities could offset their costs by selling recovered minerals. It’s still early-stage, but it represents the kind of circular thinking that could make salt production genuinely more sustainable.
Certifications and Consumer Choices
If you’re buying salt for your kitchen and want to choose a more sustainable option, your choices are limited but growing. Friend of the Sea, a project of the World Sustainability Organization, has published a certification standard specifically for sustainable sea salt production. Products meeting their criteria can carry the Friend of the Sea eco-label. Beyond that, there are few widely recognized third-party certifications for salt sustainability.
As a practical matter, solar-evaporated sea salt generally has the lowest energy footprint of any production method. Mined rock salt and heavily processed table salt require more energy and carry more environmental risk. That said, salt is used in such small quantities in cooking that the environmental difference between brands on your shelf is minimal compared to how salt is used industrially, especially for de-icing roads and in chemical manufacturing, which together account for the vast majority of global salt consumption.