What type of contaminant is Iron classified as?

Iron is classified as a secondary contaminant. Secondary contaminants are substances that do not pose a health risk but can affect the aesthetic qualities of water, such as its taste, odor, or color. Although iron is naturally occurring and critical for biological systems, elevated concentrations in drinking water can lead to staining of laundry and plumbing fixtures, imparting an undesirable metallic taste.

In many water treatment scenarios, the presence of iron is monitored not for acute health effects, but to ensure that the water meets standards for quality and customer satisfaction. This differentiation is important because primary contaminants are those that have health-related criteria, while secondary contaminants focus on consumer acceptance. Such knowledge helps water operators maintain a balance between safety and quality in the water supply.