Water softeners: How much sodium do they add?
I'm on a low-sodium diet and paying attention to my sodium intake. How much sodium does a water softener add to tap water?
Answer From the Mayo Clinic
from Sheldon G. Sheps, M.D.
Regular tap water contains very little sodium. The amount of sodium a water softener adds to tap water depends on the "hardness" of the water. Hard water contains large amounts of calcium and magnesium. Some water-softening systems remove calcium and magnesium ions and replace them with sodium ions. The higher the concentration of calcium and magnesium, the more sodium needed to soften the water. Even so, the added sodium doesn't add up to much.
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." The majority of sodium in the average diet comes from table salt and processed foods. Thus, the best way to decrease the sodium in your diet is by cutting back on table salt and processed foods.
If you're on a diet that calls for very little sodium and you're concerned about the amount of sodium in your softened water, talk with your doctor. He or she may suggest testing the sodium concentration of your water or switching to a type of water-purification system that doesn't replace magnesium and calcium with sodium, but rather with potassium.