What is indicated by colour testing in water quality assessment?

Color testing in water quality assessment is primarily used to indicate the presence of dissolved substances in the water. When water samples are color tested, the color intensity can correlate with the concentration of various dissolved materials, such as metals, salts, or organic compounds, which can affect the overall quality of the water.

Dissolved substances can include nutrients, toxins, and other chemicals that may not be visible in their solid forms. The color observed in the water sample can help to identify potential contamination and guide further testing or remediation efforts.

This method is preferred for diagnosing issues related to water quality since the color can change based on specific dissolved pollutants, helping water quality professionals identify the source and severity of contamination. In contrast, the other options focus on different aspects of water quality that do not specifically relate to what color testing indicates.