Ontario Operator-in-Training (OIT) Practice Exam

Which of the following is considered a secondary drinking water standard?

1. Nitrate

2. Fluoride

3. Microbial Contaminants

4. Chlorine

The correct answer is: Fluoride

Fluoride is considered a secondary drinking water standard because secondary standards are based on aesthetic effects rather than health effects. They are generally established to regulate substances that can affect the taste, odor, or appearance of drinking water, which in turn can impact public acceptance and consumption. Fluoride, while it is often added to drinking water for its dental health benefits, can also lead to undesirable taste and color changes if present in excessive amounts. This makes it a good example of a substance regulated under secondary standards. Other options listed, such as nitrate, microbial contaminants, and chlorine, are primarily focused on health-related concerns. Nitrate can cause serious health issues, especially in infants, which categorizes it under primary standards, while microbial contaminants are direct indicators of water safety, and chlorine, commonly used for disinfection, relates more to health safety than aesthetic qualities. Therefore, these do not fit the criteria for secondary standards as neatly as fluoride does.