According to the Water Quality Association, an ion exchange water softener adds approximately 8 mg/L of sodium for each grain per gallon of hardness removed.
amount of sodium ingested in mg per day =
= (liters of water ingested per day) * 8 * ((source water hardness in grains per gallon) - (final water hardness in grains per gallon)) =
= (liters of water ingested per day) * 8 * ((source water hardness in mg/L) - (final water hardness in mg/L)) / 17.2
where:
• 1 grain per gallon = 17.12 mg per L
• 1 grain = 64.7989 mg; 1 gallon (US) = 3.7854 liters
For patients for whom this amount of sodium is a problem, options include:
(1) having a separate line of source water that bypasses the water softener which can be used for drinking and cooking
(2) having the water from the softener go only to the hot water heater
(3) using potassium chloride for the regenerating brine
(4) using an alternative form of water softener
