Salt is one of the most abundant minerals on the earth, making saltwater contamination a common problem throughout the world. Not only is salt extremely common, but it is also difficult to remove from water to make it safe to drink. In fact, the most common types of home water treatment systems, refrigerator filters and standard water pitcher filters, are unable to remove salt from water. In this article, you can learn how salt gets into water, why removing salt from water is important, and the types of water treatment systems that can give you the water quality you need.
How does salt get into water?
Most groundwater sources contain traces of salt, but other environmental factors determine the levels of salt that are present in water. Natural salt deposits, road salt, discharge from water softeners, and proximity to the ocean or other saltwater bodies can all elevate the levels of salt in a groundwater supply.
Natural deposits
Regardless of how close a groundwater source is to the ocean or another salty body of water, it can still contain elevated levels of salt from natural deposits. When testing your well, take note if the salt levels are elevated during a specific season or whether they are year-round. A higher salt concentration in the winter may signal contamination from salt used to treat icy roads. All well owners, regardless of the location or climate of their region, should test for salt in their water and invest in the appropriate treatment systems to deal with it if needed.
Road salt
Road salt is particularly a problem for well owners during the winter in cold climates. When salt is used to lower the freezing point of ice on roads, it seeps into the ground and can contaminate groundwater supplies. About 23 million tons of salt are applied to roads each year in the United States, causing sometimes significant groundwater contamination during the winter. In many cases, a well may be located under a road or near a road salt storage location. To test if road salt is a source of contamination, check whether the salt levels are elevated in the winter months and decline in the others. If the contamination is year-round, it is likely stemming from a source other than road salt.
Water softeners
Water softeners are a type of water treatment system designed to remove water-hardening minerals from water. While these units are effective, they use salt in the softening process. For water to be softened, it must flow through a bed of resin beads that contain sodium or potassium ions. These ions exchange themselves for calcium and magnesium ions in the water. The result of this process is soft, slightly salty water. The amount of salt left in water that is treated by a water softener is not enough to harm you unless you are on a low-sodium diet. Note that the average American consumes over 3,300 mg of sodium per day according to the CDC, and the recommended daily value is 2,300 mg. Because the American diet is already so rich in sodium, it is recommended to remove the salt from your drinking water treated by a water softener, particularly if the incoming water supply contains a great deal of hardness. Treating the water will also help remove other contaminants that may give your water foul tastes or odors.
However, water softeners have a much bigger problem than adding a small amount of sodium to the treated water. After a period of time that is dependent on several factors, a water softener must regenerate the resin beads so that they may continue to effectively soften water. To regenerate the beads, a salty brine flows through the resin tank and is subsequently discharged. This contaminates the wastewater line with water rich in salt, a contaminant that is famously difficult to treat in municipal water supplies.
Learn more: What is a water softener and how does it work?
Saltwater bodies
Bodies of salt water are a major contaminant of fresh groundwater supplies. The closer a water source is to the ocean or another body of salt water, the more likely contamination will occur. Saltwater intrusion, the pollution of freshwater supplies by bodies of salt water, is a problem many coastal locations face. A variety of conditions, including drought, storm surges, and high tides, can allow salt water to infiltrate freshwater aquifers.
Learn more: What is brackish water and how do you treat it? | Navigating saltwater intrusion
Why is salt so hard to remove from water?
Salt is difficult to remove from water because it dissolves easily and creates strong bonds that require great energy to break. This energy can be in the form of great heat, such as in a distiller, or great pressure, as seen in reverse osmosis systems. The energy cost of reverse osmosis is less than that of distillation, leading new desalination plants to use reverse osmosis plants to separate salt from water. Salt is so difficult to remove from water that many municipalities have banned the use of water softeners. This ban prevents rising water treatment costs that city water treatment must incur if the water contains high salt content.
Is salt in water bad for you?
A small amount of salt in water is okay to drink, but drinking water that is rich in salt can be deadly. Note that you should never drink seawater, as it contains enough salt to dehydrate you instead of helping hydration. According to the New York State Department of Health, sodium levels in water should not exceed 270 ppm (mg/L) for those on moderately restricted sodium diets and should remain lower than 20 ppm for those on extremely strict sodium diets. The daily recommended value for sodium intake is around 2,300 mg according to the CDC, and the average American consumes around 3,300 mg per day. Because the American diet is so rich in sodium, keeping the salt content of your water at a minimum can be beneficial.
Does salt in water help hydration?
Electrolytes like sodium perform many functions, including maintaining your body’s water levels, balancing your pH, and delivering nutrients to your cells. Table salt contains about 98% sodium chloride and 2% other minerals like calcium, magnesium, and potassium. As a result, when adding salt to your water, you are mostly replenishing sodium and chloride levels and not other electrolytes like potassium and magnesium.
Salt in water helps aid hydration if you have been sweating, but it is not necessary to add salt to your water for everyday use. In fact, adding sodium to your water can be harmful if you already consume too much in your diet. If you need to replenish electrolytes from exercise, consider an electrolyte drink that replenishes sodium, potassium, chloride, magnesium, and other electrolyte levels that you lose during exercise. If you do not have access to an electrolyte drink or other means of electrolytes, salt on its own can aid in hydration by replenishing your sodium and chloride levels. If you do not exercise or sweat regularly, ask your doctor before consuming salt in your water regularly. The average American’s diet is already high in sodium, and adding more to your water may be detrimental to your health.
Do I need to remove salt from my water?
Salt should be removed from your drinking water if sodium levels are above 60 ppm (mg/L) according to the EPA. However, this guideline is based on enhancing the aesthetic qualities of water, not the safety of it. Water treatment plants are not required to keep sodium levels below 60 ppm, and each state may have a lower or higher guideline depending on the conditions of the region. If you are on a sodium restrictive diet, you should treat your water to remove sodium if its concentration is above 20 ppm.
If your home uses well water, you should have your well tested at least once each year for a variety of contaminants, one of which is salt. Well water is more likely to contain high levels of sodium than municipal water, so you may need to incorporate a treatment system that can remove this salt if sodium levels are too high. If you are curious how much sodium is too much for drinking water, assume that each member of your home consumes the recommended two liters of water each day. Multiply the mg/L (or ppm) of sodium in your water by two, and you will get the total amount of sodium consumed by drinking water each day for each person. For example, 100 ppm of sodium in your water means each person in your home likely consumes about 200 mg of sodium from water every day. This is less than 10% of the federal recommended daily amount of sodium (2300 mg) in your diet. Consequently, 100 ppm of sodium in your water should be fine for drinking unless someone in the home is on a sodium restrictive diet.
Best water filters for removing salt
The three most common types of home water treatment methods for removing salt from water are reverse osmosis, deionization, and distillation.
Reverse osmosis
Reverse osmosis (RO) systems force water through a semipermeable membrane at high pressure to reduce a vast majority of contaminants from water. The pressure in RO is high enough to remove 95-99% of salt from water. Note that reverse osmosis is excellent at desalinating water that is slightly salty, but extremely salty water may need a more powerful RO system than a standard home unit. However, salt water, such as seawater, requires higher pressures to effectively treat water than home RO treatment systems can deal with. If you are removing salt from softened water or from your well, a home reverse osmosis system is an excellent treatment method.
RO systems are almost always used in point-of-use applications, meaning they only treat water at one location in your house, such as your kitchen sink. While whole-house reverse osmosis exists, it is typically not used unless absolutely necessary.
Learn more: What is a reverse osmosis system and how does it work?
Deionization
Water deionization systems use a combination of cation and anion exchange resins to remove dissolved salts, minerals, and other ions from water. Deionization systems are predominantly used in industrial applications, but they can also be used in the home. Because deionized water contains so few minerals, its taste is often described as flat and dull. For drinking purposes, you will likely want to incorporate a remineralizing alkaline filter after your deionization system.
Learn more: What is deionized water?
Distillation
Water distillers produce extremely pure water by boiling water, condensing the resulting vapor, and collecting the condensation. The process of distillation mimics that of the natural hydrologic cycle. As a result, distilled water is some of the most pure water that you can get from a home water treatment system. However, the process of distillation is slow, producing about one gallon of water every four hours in a standard countertop distiller. Home water distillers can produce enough water for drinking, but this water output is likely not enough to use for cooking. If you wish to use desalinated water for cooking or other uses, consider another treatment method.
Learn more: What is distilled water and is it safe to drink?
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