CRCST Practice Exam 2025 - Free CRCST Practice Questions and Study Guide

Reverse osmosis is the correct answer because it is a water purification system that uses a semi-permeable membrane to remove organic materials from the water. Reverse osmosis works by applying pressure to the water, pushing it through the membrane, which traps impurities such as bacteria, viruses, and organic compounds, resulting in purified water on the other side. This process effectively removes a wide range of contaminants, making it a popular choice for producing high-quality, clean water in various settings.

In contrast:

- Filtration typically uses a physical barrier to separate impurities from water, but it may not be as effective at removing all organic materials compared to reverse osmosis.

- Deionization removes ions from water using ion exchange resins but does not specifically target organic materials.

- Distillation involves boiling water to create steam, leaving impurities behind, and then condensing the steam to produce pure water. While it is effective at removing many contaminants, including some organic materials, it does not rely on a semi-permeable membrane like reverse osmosis.