Rhode Island Journeyman Plumber Practice Exam

What is a primary purpose of a backflow preventer?

1. To reduce water pressure

2. To maintain water temperature

3. To prevent contamination of potable water

4. To filter particulates from water

The correct answer is: To prevent contamination of potable water

A backflow preventer is a critical device in plumbing systems, primarily designed to prevent the backflow of water into the potable water supply. This function is essential for maintaining the safety and quality of drinking water by ensuring that contaminants from non-potable sources do not mix with or enter the municipal water supply. When there is a drop in pressure in the system, without a backflow preventer in place, water could potentially flow backward, bringing with it harmful substances or pollutants. By installing a backflow preventer, a one-way valve mechanism is utilized that allows water to flow in one direction only, significantly reducing the risk of contamination. This is vital for public health and complies with plumbing codes and regulations aimed at protecting water supply systems. The other options relate to aspects of water management but do not capture the critical role of a backflow preventer. Reducing water pressure and maintaining temperature are important functions in plumbing systems but are not specifically associated with preventing contamination. Filtering particulates from water, while beneficial, addresses a different aspect of water treatment, focusing on clarity and cleanliness rather than on safeguarding against contaminant intrusion.