What type of samples should be representative of the system when testing?

The correct answer is that bacteriological samples, often referred to as "Bacti samples," are specifically designed to test for the presence of pathogens in water systems and should be representative of the water being drawn from the system. When assessing water quality, especially for drinking water, it is crucial that these samples accurately reflect the conditions of the water supply.

Bacti samples typically involve testing at various points within a distribution system to ensure that results accurately represent the water's microbial quality across different locations and times. This is essential since contamination can vary significantly based on the source, treatment, and distribution conditions.

In contrast, other types of sampling methods, such as composite and grab samples, serve different purposes. Composite samples collect multiple portions of water over time, which may not provide an accurate picture of any specific moment's contamination levels. Grab samples, taken from a single location at a specific time, may miss variations in water quality.

By understanding the significance of Bacti samples, you can appreciate their role in ensuring public health is safeguarded through effective monitoring of water systems.