What is the maximum horizontal length of indirect waste piping and local waste piping handling sanitary wastes?

• A. 10 feet
• B. 20 feet
• C. 30 feet
• D. 40 feet

Answer: (C)

The main idea is knowing how far indirect waste piping and local waste piping can run horizontally before they must be vented or rearranged. The maximum allowed length is thirty feet. Keeping the run within this limit helps ensure the waste is adequately vented so trap seals aren’t siphoned and flow remains unimpeded. If the run would exceed this distance, you’d need to add venting or adjust the piping layout to keep the indirect/local waste within the permitted reach, preventing backflow issues and improper drainage.