Which type of water contains a high concentration of minerals such as calcium and iron?

Hard water is characterized by its high concentration of dissolved minerals, particularly calcium and magnesium, and often contains other minerals like iron as well. This type of water results from rainwater passing through mineral-rich areas, where it picks up these essential minerals from the soil and rock. As a result, hard water is often associated with certain benefits, including providing essential nutrients and contributing to dietary mineral intake.

In contrast, soft water typically has a low mineral content and is treated to remove calcium and magnesium, making it less suitable for dietary needs in terms of minerals. Filtered water can vary in mineral content depending on the filtration process, and tap water can be either hard or soft, depending on the source and local treatment practices. Therefore, the defining characteristic of hard water being rich in minerals directly supports why it is the correct answer to this question.