Hard water is water that contains high levels of minerals like calcium and magnesium. While hard water is generally safe to drink, it can cause problems for industrial equipment and domestic plumbing over time. Common issues with hard water include a lack of suds when soap is used and limescale buildup. Water softening methods like ion exchange and lime softening are used to reduce the adverse effects of hard minerals by removing calcium, magnesium, and other cations, making the water more compatible with soap and extending the lifetime of pipes and appliances.