Do I Need to Shut Off or Drain the Backflow Device Seasonally, and How?

Wondering whether your backflow preventer needs a seasonal shutdown? In San Diego’s mild climate, the answer is usually “no”—but there are important exceptions. If you’re in a colder inland microclimate or you have an exposed irrigation assembly, a quick seasonal drain can prevent expensive freeze damage.

Below is a clear guide on when and how to do it safely, and when to call Atlas Backflow Services for help—including our backflow testing san diego experts recommend to keep you compliant and protected.

Quick Answer

• San Diego coastal areas: Seasonal draining is typically not required.

• Inland/cooler zones or freeze warnings: Drain exposed irrigation backflow preventers (RPZ, PVB, DCVA) to prevent cracking.

• Never shut down fire protection backflow without permits and coordination with your AHJ.

• How to drain: Shut upstream valve, relieve pressure, open test cocks, and allow water to drain; insulate if leaving in place.

• Reactivation: Close test cocks, repressurize slowly, and schedule our backflow testing san diego recommend with Atlas Backflow Services.

When Seasonal Draining Makes Sense in San Diego

San Diego rarely freezes, but neighborhoods at elevation or inland (Ramona, Valley Center, Poway, Escondido, Alpine, Julian) can see overnight lows below 32°F. In these areas, exposed irrigation backflow preventers are vulnerable.

Water trapped inside can expand when frozen and crack the bronze body, leading to leaks and costly replacements.

Consider seasonal draining or temporary freeze protection if:

• You’ve had frost on consecutive nights or a freeze advisory is issued.

• Your backflow assembly is above ground, uninsulated, and feeds irrigation.

• The device sits in a windy, shaded location that stays colder.

For many coastal or urban properties, insulation and vigilant monitoring during cold snaps are enough. When in doubt, call Atlas Backflow Services for guidance and our backflow testing san diego recommend to ensure your device is safe and functional.

When You Should Not Shut Off or Drain

• Fire protection backflow (sprinkler systems): Do not shut off or drain seasonally. Disabling fire protection is unsafe and may violate code and insurance requirements. Any service requires coordination with your fire authority and permits.

• Domestic water backflow serving your building: Typically remains active year-round for health and safety. If you suspect freeze risk, consult us about insulation, heat-trace options, or relocation rather than shutdown.

If you’re unsure which assembly you have, contact Atlas Backflow Services. We’ll identify the device, advise best practice, and provide our backflow testing san diego recommend to verify performance.

Know Your Device Type

Different devices drain slightly differently:

• RPZ/RP (Reduced Pressure Zone): Has a relief valve that discharges. Always installed above grade; most vulnerable to freeze cracks if left full.

• PVB (Pressure Vacuum Breaker): Common on irrigation. Upright bonnet and air inlet—must be above downstream sprinklers.

• DCVA/DCV (Double Check Valve Assembly): May be in a box or vault; less tolerant of freezing water if submerged.

Step-by-Step: How to Shut Off and Drain an Irrigation Backflow

Safety first: If you’re not comfortable or your device is tied to critical systems, call Atlas Backflow Services. Improper draining can cause damage. We can handle the winterization and include our backflow testing san diego recommend at reactivation.General supplies: Flat screwdriver, adjustable wrench, towels/bucket, insulation cover.

1. Turn off the water supply upstream

2. Locate the upstream shutoff valve before the backflow assembly. Turn it fully off.

3. Confirm by watching a pressure gauge downstream drop, or by opening a nearby hose bib to see pressure fall.

4. Relieve downstream pressure

5. Open a downstream valve or hose bib to bleed off pressure trapped in the system.

6. Open test cocks to vent and drain

7. Most assemblies have two to four small test cocks with slotted screws.

8. Slowly turn each test cock 90 degrees to the open position. Start with the highest and finish with the lowest to allow air in and water out.

9. Device-specific tips

10. RPZ: With upstream off and downstream pressure relieved, the relief valve should stop dripping once drained. Crack unions or use the lowest plug to ensure all water exits. Don’t cap the relief vent—it must remain free.

11. PVB: Open both test cocks. Turn the two shutoff handles to a 45-degree position (half-open) so water can drain from the ball cavities. Water should stop trickling after a short while.

12. DCVA: Open test cocks. If the unit sits in a box, make sure the box drains; standing water in a freeze can still crack the body. Loosen downstream union briefly to release trapped water if needed.

13. Protect the assembly

14. Install an insulated backflow cover on exposed devices. For PVBs and RPZs, leave vents clear so trapped moisture can escape. Avoid taped plastic bags that trap condensation.

Optional (irrigation systems): Blow out sprinkler lines with compressed air. This is best left to pros; too much pressure can damage valves and heads. We use controlled pressures and proper adapters to protect your system.

How to Reactivate in Spring

1. Inspect visually

2. Check for cracks, corrosion, and damaged insulation. Confirm all test cocks are still open.

3. Close test cocks and valves in sequence

4. Close all test cocks fully.

5. Return downstream and upstream shutoff handles to the closed position if they were left at 45 degrees.

6. Slowly pressurize

7. Open the upstream shutoff valve very slowly to prevent water hammer.

8. Once filled, open the downstream valve gradually and check for leaks.

9. Test for compliance and performance

10. Schedule Atlas Backflow Services for our backflow testing san diego recommend. We’ll certify the device, verify check and relief functions, and record the test with your AHJ if required.

Common Mistakes to Avoid

• Leaving devices half-full: Trapped pockets can still freeze and crack.

• Capping the RPZ relief vent: This defeats the safety function and can cause flooding indoors if the device discharges.

• Shutting down fire protection backflow: Never without permits and professional coordination.

• Skipping reactivation testing: Many jurisdictions require testing after service. Our backflow testing san diego recommend ensures you’re compliant and safe.

Why Choose Atlas Backflow Services

• San Diego expertise: We know local microclimates, AHJ requirements, and best practices for seasonal protection without compromising safety.

• Certified testing and repairs: From irrigation to domestic and fire assemblies, we provide code-compliant service, including our backflow testing san diego recommend.

• Transparent guidance: If you don’t need seasonal draining, we’ll say so—and recommend insulation or relocation options that fit your property and budget.

FAQs

• Do I need to drain my backflow device every winter in San Diego?

  • Typically no for coastal areas. Yes or recommended for exposed irrigation assemblies in colder inland zones or during freeze warnings.

• Can I just wrap it with a towel?

  • Insulation helps, but it doesn’t remove water that can freeze. Draining plus a proper insulated cover is more reliable.

• Will draining void anything?

  • Not when done correctly. However, many AHJs require testing after service. Book our backflow testing san diego recommend to stay compliant.

Ready for Peace of Mind?

If you’re unsure whether your property needs seasonal draining—or you want it handled professionally—contact Atlas Backflow Services. We’ll assess your risk, perform winterization when needed, and handle spring reactivation with our backflow testing san diego recommend so your system stays safe, efficient, and compliant all year long.