After years in commercial irrigation, the same mistakes keep costing crews thousands on every project. Here's what to watch for:

1. Undersizing mainlines for future expansion

Everyone designs for today's zones. Smart contractors design for the zones they'll add in 2-3 years. Ripping up parking lots to upsize a mainline is a conversation nobody wants to have with a property manager. Add 20% capacity overhead — the pipe cost difference is negligible compared to the retrofit.

2. Ignoring pressure loss through backflow preventers

I've seen systems spec'd at 65 PSI static that actually deliver 42 PSI at the heads after the RPZ and mainline friction loss. Map your actual dynamic pressure at every POC before you size anything. A $200 pressure test saves a $15,000 re-pipe.

3. Skipping wire tracking on large commercial sites

Two-wire systems save money up front. But when you're chasing a fault through 3,000 feet of wire under a parking lot with no as-built, you'll wish you'd spent the extra $800 on a wire tracker and proper documentation from day one.

These aren't edge cases — they happen on job sites every week. The difference between a crew that stays profitable and one that eats change orders is usually just preparation.

We break down stuff like this daily inside IrrigationPros. If you're running a commercial irrigation operation, this is your room.