Irrigation System Design: Trenching, Well Pump, and Backflow

Designing a system starting on municipal water (70 PSI, 10 GPM), later switching to a well. Questions on shared trenching, pump without pressure tank, deadhead protection, and backflow prevention.

Key Recommendations

• Trenching: Run 110/220V in conduit at 18" depth; irrigation pipe and low-voltage wire at 10–12".
• Well Pump: Use controller's pump start terminal with a relay. Consider a holding tank (cistern) to buffer well yield.
• Deadhead Protection: Install a pressure relief valve on mainline to recycle water if a zone valve fails.
• Backflow: A double-check valve assembly can be buried in a valve box. Check local code; some require above-grade installation.
• Drip Tubing: Bury at least 2" to prevent UV degradation.

All questions are valid; the design is on the right track.