What types of substances are commonly tested to assess water quality?

The assessment of water quality typically requires a comprehensive evaluation of various substances to provide a complete picture of the water's safety and health for both environmental and human use. Commonly tested substances include nutrients, such as nitrogen and phosphorus, which can indicate the level of organic pollution and the potential for algal blooms. Pathogens are also crucial to test, as they signify the presence of microorganisms that could pose health risks to humans and wildlife.

In addition to nutrients and pathogens, heavy metals are significant indicators of contamination. They can originate from various sources, including industrial discharges and urban runoff, and their presence can have serious implications for the ecosystem and human health.

Therefore, the combination of testing for both nutrients and pathogens along with heavy metals gives a well-rounded evaluation of water quality, making the selection that combines both these groups of substances the most accurate choice. Testing solely for physical parameters, while important, does not provide the necessary insight into chemical and biological risks associated with water quality.