Which one of these is NOT a method for identifying contaminated water?

The correct choice is based on understanding that identifying contaminated water requires established methods and practices, which are critical for maintaining water safety and quality. Ignoring regulations about pollutant levels does not contribute to identifying contamination; in fact, it undermines efforts to monitor and protect water resources. Regulatory frameworks exist to guide water testing and ensure safe drinking water, so disregarding these cannot be considered a valid method for identifying whether water is contaminated.

In contrast, visual inspection for color changes can provide preliminary indications of contamination, laboratory analysis measures specific pollutants quantitatively, and sensory tests for odor can reveal potential issues based on noticeable characteristics. Each of these methods is recognized as a legitimate approach to assessing water quality, while ignoring regulations directly contradicts the integrity of water safety practices.