When people discuss installing water filtration systems in their homes, they often have many questions about them. For example, can these systems filter out most impurities? During the water-softening process, is the sodium chloride (table salt) used by the water softener harmful to the human body?

Central water softeners use a physical cation-exchange process to replace calcium and magnesium ions that cause water hardness with sodium ions. Many consumers question the potential negative health effects of drinking this sodium-enriched softened water.

Sodium is an essential nutrient and plays important roles in maintaining fluid balance, nerve function, and muscle function. However, excessive sodium intake can contribute to high blood pressure and cardiovascular problems.

Data indicates that many adults in North America consume more sodium than recommended. People with certain medical conditions or who have been advised by their doctors to limit sodium intake should take the additional sodium from softened water into consideration when managing their diet.

According to the Water Quality Association, there is no evidence that drinking properly softened water causes cardiovascular or other health problems in healthy individuals.

Based on the hardness of water in the Greater Toronto Area, a typical central water softener may add a measurable amount of sodium to the water. For example, if softened water contains 80 milligrams of sodium per liter, a person drinking 8 glasses of water (approximately 2 liters) per day would receive about 160 milligrams of additional sodium from the softened water. For most healthy adults, this is a relatively small contribution to total daily sodium intake.

Conclusion: For most healthy adults, the sodium added by a water softener is unlikely to have a significant negative impact on health. However, people who have been advised to restrict sodium intake, as well as families with young children, may prefer to leave a kitchen faucet or other drinking-water faucet connected to the unsoftened water supply when installing a water softener. Alternatively, installing an additional water purifier, such as a reverse osmosis or distillation system, can reduce the sodium introduced by the water softener.

By Michael Chiu, MWS, CI
Previously published in Ming Pao Daily News – Updated and Revised in 2026