DIY vs. professional sprinkler blowout: what can go wrong

You can blow out a small system yourself, but most homeowners don't have the airflow to do it well, and the parts that break are expensive.

The airflow problem

Most home compressors put out about 4–10 CFM. Professional blowout rigs are typically 185 CFM trailer units that cost $20,000+. With a small compressor you have to run each zone in many short cycles and still risk leaving water in low spots. Utah State University Extension notes that systems without drain valves need compressed air and suggests hiring a professional.

Overpressure risk

Most residential systems run around 40–60 PSI. Pushing too much pressure, or blowing air with every valve closed, can pop heads off or crack PVC fittings. Blowing air for too long through a dry zone can also heat up plastic parts.

The backflow preventer: the part that breaks first

The backflow preventer is usually above ground and is the most freeze-sensitive component of the system. A cracked backflow is a common spring surprise. If it's a testable assembly, cities like Salt Lake City also require annual testing.

Freeze damage costs (local pricing)

If you DIY anyway

• Close the irrigation water supply first and relieve pressure.
• Keep air pressure at or below your system's normal operating pressure.
• Run one zone at a time, and never blow air with every zone valve closed.
• Wear eye protection and never stand over a sprinkler head.
• Don't blow air through the backflow preventer itself. Drain it per the manufacturer.