Which contaminants are typically tested in community water quality assessments?

• A. Oxygen, nitrogen, potassium
• B. Sodium chloride, calcium, magnesium
• C. Chlorine residual, pH, turbidity
• D. Bacteria, nitrates, lead

Answer: (D)

In community water quality assessments, the focus is on contaminants that can directly threaten health and are routinely checked to protect consumers. Bacteria signal potential microbial contamination and GI illness, nitrates indicate agricultural or sewage input that can cause serious problems for infants, and lead reveals deterioration of older plumbing that can impair neurodevelopment. These health-related contaminants are central to standard drinking-water monitoring. The other options describe substances or parameters that affect taste, aesthetics, or treatment performance rather than representing health-based contaminants: minerals like calcium and magnesium influence hardness, sodium chloride affects salinity, and chlorination residual, pH, and turbidity are process indicators or aesthetic measures rather than contaminants themselves.