Water softeners indirectly add sodium to the water by replacing the scale-causing minerals calcium and magnesium. These are removed with a non-scale-forming mineral: sodium.
An 8-ounce (237-milliliter) glass of softened water generally contains less than 12.5 milligrams of sodium, which is well within the Food and Drug Administration’s definition of “very low sodium”, according to Sheldon G. Sheps, M.D. at the Mayo Health Clinic.
We typically have harder water in Minnesota, and the average sodium content would be around 10-30 milligrams in an 8 oz glass of water. In comparison, ocean water contains 1,035 milligrams of sodium in 8 oz of water.
Various sources, such as the National Research Council, have gone on the record indicating that drinking softened water does not pose any health risks. However, because a water softener is removing the calcium and magnesium from the water and replacing it with sodium, it may change the texture, taste or feel of the water and may be undesirable for some.
If you do not want to drink softened water, there are other options. Your kitchen cold water can be bypassed or can utilize a drinking water purification system such as reverse osmosis.