Removes hardness minerals
Calcium and magnesium are exchanged for sodium ions. Result: no scale, soap that lathers, spot-free dishes, longer-lasting appliances.
Removes contaminants
Chlorine, sediment, taste, odor, and many organic compounds. Result: better-tasting water, no chemical smell, protected appliances and skin.
Do you need both?
Usually yes. Most Kalispell, Whitefish, and Columbia Falls homes get city water that's both hard and chlorinated. A softener handles hardness; a whole-home filter handles chlorine. They work side-by-side and dramatically improve every water-using fixture in the home.
What about reverse osmosis?
RO is a polishing filter for drinking water only. It removes dissolved solids a whole-home filter can't — lead, PFAS, nitrates, sodium. Most premium installations include a softener + whole-home filter + RO under the kitchen sink.