Rhode Island Journeyman Plumber Practice Exam

What must be installed before connecting an irrigation system to a potable water supply?

1. A backflow preventer

2. A vacuum breaker

3. A pressure reducing backflow preventer

4. A manual valve

The correct answer is: A pressure reducing backflow preventer

The connection of irrigation systems to potable water supplies must always incorporate protective devices to prevent contamination of the drinking water. A pressure-reducing backflow preventer serves a twofold purpose; it not only reduces excessive pressure that could cause damage to plumbing fixtures and lines but also acts as a vital safeguard against back-siphonage. This condition occurs when there is a drop in pressure within the supply line, potentially allowing contaminants from the irrigation system to flow back into the potable water supply. Installing a pressure-reducing backflow preventer ensures that the pressure levels are managed appropriately while simultaneously providing critical protection for public health. Therefore, having this device before connecting irrigation systems is crucial to maintain water safety standards. The other options, while relevant to water system management and backflow prevention, do not provide the same combination of pressure regulation and backflow protection that is necessary for a potable water supply connection in this context.