What is the determining factor for the minimum number of water samples required for bacteriological analysis in public water supplies according to the Safe Drinking Water Act?

The minimum number of water samples required for bacteriological analysis in public water supplies, as dictated by the Safe Drinking Water Act, is primarily determined by the population served. This approach is designed to ensure appropriate monitoring of water quality for the population that relies on the public water supply.

Bacteriological analysis is crucial because it helps identify the presence of harmful microorganisms that can pose serious health risks to the population. The guidelines generally stipulate that as the population served by a water supply increases, the minimum number of samples also increases. This is to ensure that representative samples are collected which reflect the water quality and safety for larger groups of people.

Focusing on daily population served or the specific area of the raw water supply may not adequately account for variations in water usage and exposure risks among the total population. Similarly, the amount of water treated does not directly correlate to the potential for contamination or the necessity to monitor bacteriological quality. Therefore, the population served remains the critical factor guiding sampling requirements under the Safe Drinking Water Act.