What is the required sample volume when testing finished drinking water for total coliform?

When testing finished drinking water for total coliform, the standard required sample volume is 100 milliliters. This volume is specified to ensure that the sample is sufficiently large to provide a reliable and accurate representation of the water quality. A 100 ml sample is an industry standard, as it effectively balances the need for both accuracy in detection and practicality in terms of handling and processing the sample in a laboratory setting.

Using this volume helps in achieving a suitable level of sensitivity for detecting coliform bacteria, as these microorganisms can be present at very low concentrations in water. Smaller volumes may not provide enough sample to reliably demonstrate the presence or absence of coliform, while significantly larger volumes may not be necessary for accurate testing, and could complicate the analysis process. This makes 100 ml a commonly accepted and practical approach for testing finished drinking water for total coliform bacteria.