Using water softener salt (WSS) in a bath is generally not recommended. This household product is manufactured for mechanical processes, not for cosmetic or therapeutic skin use, and its potential drawbacks outweigh any perceived similarity to bath salts. WSS is primarily used in an ion exchange process to remove hardening minerals like calcium and magnesium from a water supply. People often consider using it due to its availability and the misconception that all salt is interchangeable for bathing purposes.
The Chemistry of Water Softener Salt
The primary component of most water softener salt is highly purified sodium chloride (NaCl). This is chemically distinct from salts typically used in therapeutic baths. While some softeners use potassium chloride (KCl), sodium chloride is the most common form. WSS is manufactured to dissolve efficiently in the brine tank to regenerate the resin beads, serving a strictly mechanical function.
WSS purity is defined by a lack of insoluble matter that could foul the softening equipment. Some varieties contain industrial-grade additives designed to improve the mechanical process, such as anti-caking agents or iron-fighting compounds like sodium bisulfate or citric acid. These additives are not intended for direct, prolonged contact with human skin or the internal surfaces of a bathtub.
Potential Effects on Skin and Health
Soaking in a high concentration of WSS, which is a strong sodium chloride solution, can affect the skin through osmosis. The high sodium concentration creates an osmotic gradient that draws moisture out of skin cells, potentially leading to dehydration and dryness. This osmotic effect is contrary to the moisturizing benefits often sought from a bath.
A major concern is the presence of industrial additives and trace impurities acceptable in a mechanical-grade product but not for cosmetic use. For instance, “iron-fighter” WSS contains chemicals like sodium bisulfate to clean the softener resin. These chemicals are not designed for human exposure and can be irritating in concentrated forms. Prolonged immersion in water containing these trace contaminants is ill-advised, especially for individuals with conditions like hypertension where high sodium exposure is discouraged.
Impact on Plumbing and Fixtures
Introducing concentrated WSS into the drain system creates a highly saline solution problematic for physical infrastructure. Chloride ions, the active component, are corrosive to various metals used in plumbing and fixtures. Concentrated salt solutions accelerate galvanic corrosion, attacking the protective layers on copper, galvanized steel, and other metal components.
This increased corrosion can damage metal drain pipes, shower heads, faucets, and drain mechanisms over time. The concentrated brine is also a concern for the bathtub finish, potentially accelerating the pitting or deterioration of enamels and acrylics. Furthermore, repeatedly flushing a high volume of concentrated salt solution can negatively impact the delicate balance of a septic system by interfering with natural bacterial processes.
Recommended Bath Salt Alternatives
Many people take a salt bath for therapeutic benefits like muscle relaxation and magnesium absorption, which WSS cannot provide. The most effective alternative is Epsom salt, chemically known as magnesium sulfate (MgSO4). Unlike sodium chloride, Epsom salt is readily absorbed through the skin and helps replenish magnesium levels linked to muscle and nerve function.
Pharmaceutical-grade Epsom salt is tested to meet high purity standards for human use, ensuring it is free from industrial additives. Other suitable alternatives include cosmetic-grade sea salt or Himalayan pink salt. Although these are primarily sodium chloride, they are processed for higher purity and may contain beneficial trace minerals. These options are specifically purified for cosmetic application, guaranteeing they do not contain the anti-caking or resin-cleaning chemicals found in industrial water softener products.