How soon should you backfill a trench?

• A. After flushing the piping
• B. After completing the piping
• C. After installing the heads
• D. As you are doing the piping

Answer: (A)

Backfilling is done after flushing the piping to ensure the system is clean and functioning before it’s buried. Flushing clears debris from the trenches and fittings and allows you to verify there are no leaks or weak joints before they’re covered up. If you backfill first, dirt and rocks can be pressed into fittings or trap debris inside the lines, making it hard to detect problems later and harder to repair. Once you’ve flushed and tested, backfill in stages with proper compaction to protect the pipes and prevent settling.