Sodium, a dissolved salt, is ubiquitous in water sources. Its presence can concern individuals with dietary restrictions or those seeking purer drinking water. While naturally found in the environment, its concentration in household water can sometimes affect taste or health considerations. People often look for practical filtration solutions to manage this salinity. Understanding where this sodium comes from is the first step toward effective removal.
Identifying Sodium Sources in Household Water
Sodium enters a home’s water supply through two main pathways: natural occurrence and water treatment processes. Naturally occurring sodium results from water passing through geological deposits, dissolving minerals containing sodium chloride or other salts. In coastal regions, saltwater intrusion into freshwater aquifers can also introduce significant levels of sodium into well water.
The second major source is the traditional cation exchange water softener, a common appliance in homes with hard water. These softeners operate by exchanging “hardness” minerals (calcium and magnesium ions) with sodium ions. The resulting softened water is higher in sodium than the original source water, adding a variable amount depending on the initial water hardness. The softener introduces sodium; it does not remove it.
The Gold Standard: Reverse Osmosis Filtration
Reverse osmosis (RO) is considered the most effective point-of-use method for removing sodium from residential drinking water. The process works by applying pressure to the water to force it through a semipermeable membrane. This membrane has small pores that allow water molecules to pass through while physically blocking larger dissolved solids, including sodium ions.
Residential RO systems are highly efficient, typically achieving a sodium rejection rate between 95% and 99%. This high degree of purification makes RO technology a standard recommendation for individuals on sodium-restricted diets. The systems are commonly installed under a kitchen sink, treating only the water used for drinking and cooking. RO remains effective even when treating water that has been through a salt-based softener.
Distillation and Specialized Ion Exchange
Alternative methods to reverse osmosis also offer highly effective sodium removal. Distillation involves heating the water until it turns into steam, leaving all dissolved salts and minerals, including sodium, behind in the boiling chamber. The pure steam is then collected and condensed back into liquid water.
This process results in water with extremely high purity, often exceeding RO water quality. However, distillation is a slow method, often taking several hours to produce a single gallon, and requires significant energy to maintain the boiling temperature.
Specialized Ion Exchange (Deionization)
These specialized systems, often referred to as deionization (DI), use a combination of cation and anion exchange resins to remove nearly all dissolved salts. The resins in a DI system exchange the unwanted sodium ions for hydrogen ions and the corresponding negative ions for hydroxide ions, effectively removing the salt components. While highly effective for creating laboratory-grade water, these systems are less common for household drinking water needs than RO or distillation.
Practical Comparison of Removal Methods
When choosing a sodium removal method, considering practical factors beyond purity is important. Reverse osmosis systems offer a balance of high purity and convenience, with moderate initial costs for a point-of-use unit. They do produce wastewater, as a portion of the incoming water is used to flush the rejected salts down the drain.
Distillation units achieve exceptional purity but are characterized by a higher energy requirement and a slower production rate, making them best suited for low-volume needs. The initial cost for a countertop distiller is typically lower than a full RO system, but the operational cost per gallon is higher due to energy consumption. Deionization provides ultra-high purity but is generally the most complex and least practical option for typical residential drinking water.