Sodium is a naturally occurring mineral found in all water sources. While necessary for bodily functions, elevated levels in drinking water can concern individuals on low-sodium diets or those managing conditions like hypertension.
The World Health Organization notes that most water supplies contain less than 20 milligrams of sodium per liter, though some sources significantly exceed this amount. Reducing sodium in your drinking water is a proactive step that contributes to managing overall dietary intake. The process begins with accurately identifying the source before implementing targeted solutions.
Identifying the Source of Sodium
Reducing sodium requires knowing its source, which often involves professional testing. Sodium enters the water supply through two main pathways: natural/environmental sources and man-made systems. Natural sources include the leaching of mineral deposits from rocks and soil, especially in groundwater where sodium ions are highly soluble. Seawater intrusion and the runoff of road salt used for de-icing also contribute substantial quantities of sodium.
The most common man-made source of elevated residential sodium levels is the use of a traditional salt-based ion exchange water softener. These softeners work by exchanging hardness minerals—calcium and magnesium—for sodium ions. Depending on the initial water hardness, a water softener can raise the sodium concentration to over 300 milligrams per liter.
It is important to determine the exact sodium level in your water, especially if you use a private well. Municipal providers must report sodium concentrations if they exceed 20 mg/L. Knowing this baseline allows you to distinguish between naturally high concentrations and the sodium added by a water softener.
Managing Sodium from Water Softening Systems
If testing confirms high sodium levels result from a salt-based water softener, you can manage the issue without advanced filtration. One practical solution is to install a bypass line for drinking and cooking water. This setup allows the household to benefit from soft water for bathing and appliances, while the drinking tap uses the unsoftened water line, which contains less sodium.
Another direct approach is to switch the regeneration salt from sodium chloride to potassium chloride (KCl). Both operate using the same ion-exchange process, but potassium chloride introduces potassium ions instead of sodium ions. This substitution effectively eliminates the added sodium, which is an advantage for those on sodium-restricted diets.
Potassium chloride is generally more expensive than sodium chloride and may require up to 25% more salt to soften the same volume of water efficiently. For homeowners looking to avoid salt entirely, alternative softening technologies, often called salt-free water conditioners, are an option. These systems, such as Template-Assisted Crystallization (TAC), work by changing the structure of hardness minerals so they cannot form scale, rather than physically removing them or adding sodium.
Specialized Filtration Techniques for Removal
When the sodium source is natural or environmental, or if water softener management is insufficient, specialized filtration methods are required to physically remove dissolved sodium ions. Reverse Osmosis (RO) is the most common and highly effective point-of-use method for this purpose. This system forces water through a semi-permeable membrane designed to block virtually all dissolved solids, including sodium ions.
A properly functioning RO system can remove up to 99% of dissolved salts, making it a reliable solution for producing low-sodium drinking water. These units are typically installed under the kitchen sink to treat water for a dedicated drinking water faucet, which is a cost-effective approach. The salt rejection rate for the RO membrane is optimally between 95% and 99%.
Another highly effective removal technique is distillation, which involves boiling water into steam and then condensing the steam back into liquid water. Since sodium is nonvolatile, it is left behind as a residue, resulting in very pure water. Distillation units are typically slower and more energy-intensive than RO systems, meaning they are often used for treating smaller quantities of drinking water.
For whole-house or commercial applications, specialized ion exchange systems, often called deionization (DI), can remove sodium. These systems utilize different resins than a standard water softener, designed to exchange the sodium ion for hydrogen or hydroxide ions. While effective, these systems are complex and reserved for situations requiring high-purity, low-sodium water throughout the property.