Method

• Sodium chloride and potassium chloride soften water in the same manner. Hard water flows over a resin containing either sodium ions or potassium ions. As it does, the calcium and magnesium in the water switch places with the ions on the resin. Consequently, the softened water now contains sodium or potassium rather than minerals.
  
  

Cost

• Ion-exchange water softeners periodically require the addition of more salt. Sodium chloride and potassium chloride are naturally occurring compounds. Since extracting potassium chloride from the ground is more difficult than mining sodium chloride, potassium salt costs more.
  
  

Health Effects

• Ion-exchange softening adds either sodium or potassium to the water. Individuals who are concerned about dietary intake of sodium or who follow sodium restricted diets should avoid sodium chloride softened water. Potassium chloride is recommended in such situations.
  
  

Environmental Effects

• Unlike potassium chloride, sodium chloride is detrimental to the environment. Sodium-laden water disposed of in drain fields can contaminate groundwater. Potassium chloride encourages plant growth and contributes to soil stability making it more environmentally friendly.