A water softener is a filtration system that removes hardness-causing calcium and magnesium minerals from your water through a process called ion exchange. A water softener addresses one of the most prevalent and devastating water problems: hard water. Water softeners work through a process called ion exchange which eliminates calcium and magnesium from the water. When the hard water enters into the mineral tank, it flows through a bed of spherical resin beads. As the hard water passes through the resin, the beads grab ahold of the mineral ions and remove them from the water. The column of resin strips all the hardness out of the water as it passes through the mineral tank, and softened water flows out.