Florida Home Inspector Practice Test

What is the minimum required size for a P-trap drainpipe?

1. 2 inches

2. 1 inch

3. 1.5 inches

4. 3 inches

The correct answer is: 1.5 inches

The minimum required size for a P-trap drainpipe is 1.5 inches. This size is widely accepted in plumbing code because it provides an adequate flow of water to effectively trap odors and prevent sewer gas from escaping into the living space while also allowing for proper drainage without the risk of clogging. A P-trap is typically utilized in sinks and other drainage fixtures, where maintaining a water seal is essential for sanitation and safety. Larger sizes, like 2 inches or 3 inches, are often used for specific applications or larger fixtures but are not necessary for standard household drains. A 1-inch size would be insufficient to handle the expected flow from typical appliances and fixtures, which could lead to slow drainage or backups. Therefore, the 1.5-inch size is both the minimum requirement and a practical standard that balances functionality and efficiency in plumbing systems.