CSLB Class B General Contractor's License Practice Exam

What is the most common location for a cleanout?

1. Water heater gas pipes

2. Water supply pipes

3. Changes in direction of sewer drains

4. All of the above

The correct answer is: Changes in direction of sewer drains

The most common location for a cleanout in plumbing systems is at changes in direction of sewer drains. Cleanouts are essential access points that allow for clearing clogs and blockages in the sewer line. This is most crucial at bends or angles where debris tends to accumulate and where there is a higher likelihood of a blockage occurring. Installations typically include cleanouts at 45-degree and 90-degree turns, as well as at intervals along the run of the drain. By placing cleanouts at these strategic points, it becomes significantly easier to maintain the system and resolve any plumbing issues that may arise. While cleanouts can also be found in other locations, such as near water heater gas pipes or water supply pipes, these are not deemed the most common areas for their installation. Therefore, the focus on changes in direction of sewer drains establishes why this is the correct choice.