Which types of samples are considered microbiological samples?

Microbiological samples specifically refer to samples that are collected to test for the presence of microorganisms, such as bacteria, viruses, and other pathogens. These samples are crucial for assessing the safety of drinking water, ensuring that harmful microorganisms are not present in concentrations that could pose a risk to public health. The focus on bacteria and viruses directly aligns with the definitions of microbiology, which is the study of microscopic organisms.

The other options do not relate to microbiological testing. Lead and copper samples focus on heavy metals present in water, disinfection by-products examine by-products formed during the water disinfection process, and physical and chemical samples assess the water’s physical characteristics (like color and turbidity) and its chemical composition (such as pH and chemical contaminants). None of these options involves the analysis of microorganisms, which is why the choice of bacteria and viruses as microbiological samples is the correct one.