What is the primary characteristic of hard water?

The primary characteristic of hard water is that it contains high levels of minerals, specifically calcium and magnesium ions. These minerals are dissolved in the water and contribute to the overall hardness. Hard water can cause various effects, such as scale buildup in pipes and appliances, which can affect their efficiency and lifespan. It may also interfere with the effectiveness of soap and detergents, leading to the formation of soap scum. While hard water is generally safe to drink, the presence of these high mineral levels is what defines it as "hard." Understanding this characteristic is crucial for plumbing applications, including water treatment and system maintenance.