Sodium in drinking water
Undeniably, salt-regenerated ion-exchange water softeners add sodium to the softened water they produce. The amounts vary with the concentration of the hardness of their drinking water supply; the more calcium and magnesium in the water supply, the more sodium will be added to the product water. Softeners remove calcium and magnesium from the water to protect the pipes and hot water-using appliances in our homes.
|Initial hardness||Sodium added|
|1 gpg||8 mg/L|
|5 gpg||50 mg/L|
|10 gpg||80 mg/L|
|20 gpg||160 mg/L|
|40 gpg||320 mg/L|
While the minerals calcium and magnesium are under-consumed in our diet, the best source of these nutrients is food, not water. Consuming a diet rich in fruits, vegetables and dairy products is the most effective means to eliminate mineral deficiencies. In fact, our shortfall in dietary calcium and magnesium (and potassium) creates a condition of "salt sensitivity" where the blood pressure of many people changes based on their salt intake.
And we've known about a sodium/blood pressure relationship for about half a century. What we don't yet know is whether is is advisable to adjust our sodium intakes to try to manipulate our blood pressure when medical studies show that salt reduction triggers other "unintended consequences" as the body senses lower sodium intakes and triggers compensatory responses. Public health officials, however, did not wait to sound the alarm until they had a trial of sodium reduction -- and they still don't have any controlled medical trials of the question.
More than 30 years ago, some zealous public state health agencies went beyond simple federally-mandated monitoring of the various potential contaminants of our drinking water. Some imposed onerous public notice warning requirements unnecessarily frightening consumers. The Connecticut regulation, for example, required water utilities where testing found sodium concentrations 20 mg/L or higher to warn consumers that “your drinking water exceeds the maximum permissible amount of sodium.” Protective to a fault since tapwater containing even higher levels of sodium could be bottled and sold as “sodium free” under federal nutrition labeling rules because the amount of sodium was inconsequential to health. The modified Connecticut notice (imposed at a significantly higher threshhold level) now reads “If you have been placed on a low-sodium diet, please inform your doctor that your drinking water contains X mg/L sodium.” Responding to the same ill-informed fears, Congress has three times mandated that the U.S. Environmental Protection Agency regulate sodium as a drinking water contaminant; fortunately, each statute allowed EPA to consult the science before acting, so EPA has held three separate sets of regulatory hearings and continues to follow the scientists, not the politicians. Sodium is not a regulated drinking water contaminant.
Still, some people have been placed by their physicans on low-sodium diets? Must they sacrifice their plumbing, appliances, sparkling clothes and good grooming for their medical therapy? Fortunately not. Homeowners who wish to avoid the added sodium in softened water can either "plumb around" their softeners so the water coming to the "Cold" faucet in the kitchen sink is unsoftened or switch to more-costly potassium chloride to regenerate their softeners. Consult your physician if you've been placed on a low-sodium diet to see if you need to take either step.
In any case, the good news is that consumers can continue to enjoy the benefits of softened water.