Illinois Plumbing Code Practice Exam 2026 – All-in-One Guide for Exam Success!

A vacuum breaker is a device used in plumbing systems to prevent backflow of potentially contaminated water into the potable water supply. When installing a vacuum breaker above a commercial laundry machine, it should be positioned sufficiently high enough to prevent any backflow into the water supply.

In this case, the correct answer is 26 inches for the installation height of a vacuum breaker above a commercial laundry machine. This height provides the necessary protection to ensure that any potential backflow from the machine does not contaminate the clean water supply.

Option A (18 inches), Option B (24 inches), and Option D (30 inches) are incorrect as they do not meet the optimal height requirement for the effective operation of the vacuum breaker in this specific scenario.