Medical Device Reprocessing Association of Ontario (MDRAO) Practice Exam

What distinguishes soft water from hard water?

1. Soft water is mineralized

2. Hard water is pure

3. Soft water lacks minerals

4. Hard water contains only magnesium

The correct answer is: Soft water lacks minerals

Soft water is characterized by its low mineral content, specifically the absence or low levels of calcium and magnesium ions, which are the minerals that contribute to water hardness. The distinction between soft and hard water primarily revolves around these mineral concentrations. Soft water results from processes that remove these minerals, such as ion exchange or filtration, making it gentler on skin and appliances, and it tends to lather more easily with soap. This is why the definition of soft water focuses on its lack of minerals, as opposed to being mineralized or being "pure" in a different sense. In contrast, hard water is defined by its higher concentration of minerals, particularly calcium and magnesium, which can cause scaling in pipes and reduction in soap effectiveness. The presence of only magnesium in hard water is not accurate, as hard water can contain various other minerals as well, leading to variability in hardness levels. Thus, the correct answer consistently highlights the main characteristic of soft water being its lack of significant mineral content.