Massachusetts Plumbers Journeyman Practice Exam

How should the water supplies to clothes washers be protected against backflow?

1. By using higher pressure pipes

2. By manual valve operation

3. By an air gap or a back flow preventer

4. By using specialized washing machines

The correct answer is: By an air gap or a back flow preventer

The protection of water supplies to clothes washers against backflow is crucial to prevent the contamination of potable water. The correct method for ensuring this protection involves incorporating an air gap or a backflow preventer. An air gap is a physical separation between the end of a water supply outlet and the overflow level of a fixture, which effectively prevents backflow by allowing air into the system and eliminating any potential back-siphonage. A backflow preventer is a device specifically designed to block any reverse flow of contaminated water into the clean water supply, ensuring the safety and quality of potable water. Utilizing higher pressure pipes does not inherently protect against backflow; rather, it could potentially exacerbate the issue if there’s a failure in the system. Manual valve operation also does not provide a reliable safeguard, as it relies on the consistent engagement and disengagement by users, which may lead to human error and neglect. Using specialized washing machines does not address the fundamental issue, as the washing machine alone cannot ensure backflow prevention unless properly integrated with appropriate plumbing measures.