What does the Colilert test primarily measure in water samples?

The Colilert test is specifically designed to measure the presence or absence of total coliform bacteria in water samples. This test is crucial for assessing the microbiological quality of drinking water, as total coliforms are indicators of potential contamination by fecal material and pathogens. By using specific substrate indicators, the Colilert test can detect coliform bacteria and provide results that help determine whether the water is safe for consumption. This is particularly important in public health, as coliform bacteria can indicate that more harmful microorganisms may also be present.

The other options focus on different aspects of water quality. Chemical contaminants and heavy metals refer to specific substances that can be harmful but are not detected by the Colilert test. Similarly, measuring water temperature fluctuations does not relate to the presence of coliform bacteria or its implications for water quality, focusing instead on physical rather than biological or chemical factors.