How to Winterize Your Irrigation System in North Idaho (And Why Backflow Protection Matters)

North Idaho and the Spokane corridor get hard freezes. Water left in irrigation lines or inside a backflow preventer expands, cracks brass, and is one of the top reasons spring backflow tests fail. Winterizing is not only about dead grass — it is about not buying a new assembly in April.

When to winterize around CDA and Spokane

Aim for after the last heavy watering of the season and before consistent overnight freezes — often mid to late fall. Do not wait for the first hard freeze warning if your schedule is flexible; shops and blow-out services get slammed the same week.

High-level winterization steps

1. Shut off the irrigation isolation valve that feeds the system from domestic water.
2. Open the test cocks / drain ports on the backflow assembly per manufacturer guidance so water can leave the body (many PVBs need specific drain steps).
3. Blow out zones with appropriate air pressure — too much PSI can damage pipe and heads; use a tech if you are unsure.
4. Leave the assembly in a drained / protected state for winter (insulation helps in exposed locations; it does not replace draining).
5. Shut down the controller or set a rain/off mode so it does not call for water against a closed valve all winter.

Why the backflow device is the weak link

Sprinkler pipe is often buried below frost depth. The PVB sits above grade in the weather. That is by design for air inlet function — and it makes freeze damage more likely if water remains inside. A cracked body or destroyed check is an expensive “oops” compared to a careful fall shut-down.

Spring startup and your annual test

When you re-open irrigation in spring:

• Repressurize slowly and check for leaks at the assembly.
• Book your annual certified test once the system can hold pressure — many districts mail notices in the same season.
• If you hear spraying from the air inlet or see constant weeping, stop and call a tester before the due date.

Yearly Autopilot so spring is boring again

Pair good winterization with a recurring test plan. Our Yearly Autopilot plan is $50 standard (save $5 vs one-time) and we reach out before next year’s notice season so you are not scrambling after a shutoff letter.