Ontario Operator-in-Training (OIT) Practice Exam

Which of the following microorganisms is NOT commonly found in drinking water?

1. Bacteria

2. Viruses

3. Protozoa

4. Fungi

The correct answer is: Fungi

Fungi are not commonly found in drinking water, and this is significant for several reasons related to water microbiology and safety. While bacteria, viruses, and protozoa are well-documented and significant concerns for water quality, fungi typically require specific environmental conditions to thrive that are not usually present in properly treated drinking water systems. Bacteria are ubiquitous and can be found in various water sources, both treated and untreated. Many types of bacteria are common in drinking water, including both beneficial and pathogenic forms. Viruses, although less common than bacteria, can also be detected in water supplies and can pose serious health risks. They are smaller than bacteria and can survive longer in the environment, which makes them a concern for water safety. Protozoa are another category of microorganisms that may be present in drinking water, especially from sources that are not appropriately filtered or treated. Some protozoa can cause severe illness in humans, highlighting their significance in drinking water management. In contrast, while fungi can potentially contaminate water systems if conditions allow, they are not regarded as a primary or common constituent of drinking water, especially when proper treatment and monitoring protocols are in place. This understanding underscores the importance of effective water treatment processes in ensuring the microbiological safety of drinking water