INBDE (Integrated National Board Dental Examination) Practice Exam

What is the EPA's required limit for heterotrophic bacteria per mL of water?

1. <200 CFU

2. <300 CFU

3. <400 CFU

4. <500 CFU

The correct answer is: <500 CFU

The EPA's required limit for heterotrophic bacteria per mL of water is <500 CFU. This means that the maximum number of heterotrophic bacteria allowed per 1 mL of water is 500 colony forming units. Options A, B, and C are incorrect because they all exceed the EPA's allowed limit of <500 CFU. It is important to note that CFU stands for colony forming units and represents the number of viable bacteria in a sample. Therefore, option D is the only correct answer according to the EPA's guidelines.