Medical Device Reprocessing Association of Ontario (MDRAO) Practice Exam

Is distilled water considered sterile?

1. Yes, it is always sterile

2. No, it is not necessarily sterile or pyrogen free

3. Only if properly filtered

4. Yes, but only for a limited time

The correct answer is: No, it is not necessarily sterile or pyrogen free

Distilled water is not necessarily sterile or pyrogen-free. While distillation removes a significant amount of impurities, including many microorganisms, it does not guarantee sterility. Sterility implies the complete absence of viable microorganisms, which can only be assured through methods such as autoclaving or using sterile filtration processes. After distillation, if the water is exposed to non-sterile conditions during storage or handling, it can become contaminated. Furthermore, distilled water does not undergo the rigorous testing typically required to confirm an absence of pyrogens, which are substances that can cause fever when introduced into a sterile environment. This distinction is crucial in medical and laboratory settings where sterility and pyrogen-free conditions are critical for patient safety and reliable results. Thus, acknowledging that distilled water may be free of certain impurities but does not guarantee sterility or pyrogen safety provides an accurate understanding of its limitations in specific applications.