RPZ Backflow Preventer Maintenance

& Freeze Protection Guide

Your RPZ (Reduced Pressure Zone) backflow preventer plays a critical role in protecting your water supply from contamination. Proper maintenance and freeze protection will help extend its lifespan and prevent costly repairs. Follow this guide to keep your RPZ in optimal condition year-round.

Routine Maintenance for Your RPZ

✅ Inspect Monthly

  • Check for leaks around the relief valve, test cocks, and pipe connections.

  • Ensure there is no standing water around the unit, which could indicate a hidden leak.

  • Look for debris buildup that could interfere with the device’s operation.

✅ Annual Testing (Required by Law in most Municipalities)

  • Your RPZ must be tested annually by a certified backflow prevention tester.

  • Wildflower Plumbing & Gas can help with testing and compliance documentation—contact us to schedule.

✅ Clear the Area

  • Try to keep at least 2 feet of clearance around the RPZ.

  • Avoid covering it with landscaping, mulch, or objects that could obstruct access.

✅ After Nearby Construction or Plumbing Work

  • Flush the RPZ to remove any dirt or debris that may have entered the system.

  • If water pressure fluctuates unexpectedly, contact us to inspect the device.

Preparing for a Hard Freeze

Central Texas experiences occasional hard freezes—these are the times when most RPZs fail due to frozen water inside the unit. Follow these steps to protect your RPZ:

For RPZs with a Freeze-Relief Valve

(This valve is designed to open and release pressure if the RPZ starts to freeze.)

  1. Check the valve: Make sure it is installed correctly and functioning.

  2. Wrap exposed pipes: Use foam pipe insulation on all supply and return lines.

  3. Install an insulated RPZ cover: Wildflower Plumbing & Gas recommends using a heavy-duty weatherproof insulated cover for added protection.

  4. Monitor during a freeze: If water is actively dripping from the freeze relief valve, it is working as designed. If it stops dripping and temperatures are below freezing, call us immediately.

For RPZs With & Without a Freeze-Relief Valve

(RPZs without a Freeze-Relief Valve require more proactive protection, as they will not automatically relieve pressure if frozen.)

Drain and Shut Off Water Supply (if freezing temperatures are expected for an extended period and water use is not needed):

Turn off the supply valve near hose bib / spigot. This stops water from flowing to your RPZ.

Open both “check valves” (these are green on our RPZs) on the RPZ itself so they’re running parallel with the RPZ and pipe. In the diagram above they are labeled “Shut-Off #1” and “Shut-Off #2. In the diagram both valves are open; in the image above on the left, one is open and one is closed.

Opening the inlet valve where water enters the RPZ (“Shut-Off #1”), and opening the outlet valve where water exits the RPZ (“Shut-Off #2”), allows water to exit the RPZ - you want this. If this is not done, water will be trapped inside and can freeze.

Locate test cocks #2, #3 and #4 (refer to diagram above). These are the 3 cylindrical pieces on top of the RPZ, and the fourth off to the side (in the image below; test cock #1 is on the left - do not mess with test cock #1):

Turn test cocks #2, #3 and #4 slightly to the left (one-quarter turn with a flathead screwdriver so the flathead piece is parallel with the test cock body) so the flathead piece is aligned vertically. This allows air in, lets water out, and prevents pressure buildup.

Don't turn the fourth test cock (test cock #1, off to the side) because it is on the supply side of the valve. If you open it, it will spray water out.

Cover and insulate the RPZ with an insulated RPZ cover.

For Active Water Use During a Freeze:

  • Let a nearby outdoor faucet drip slightly to keep water moving.

  • Wrap the RPZ and pipes with insulation, ensuring full coverage.

  • Consider heat tape if the RPZ is in an exposed location.

Monitor for Freezing Signs:

  • If water stops flowing or pressure drops, the RPZ may be frozen.

  • DO NOT apply direct heat with an open flame. Instead, use warm towels or a hairdryer to gradually thaw the unit.

🚨 Follow these steps to keep yours out of our 'RPZ Graveyard' of frozen, cracked RPZs! 🚨

Need Help? Call the Experts!

We can help with installation, testing, and repair. Contact us today!


📞 (512) 292-1966 (call or text)
📧 INFO@WILDFLOWERPLUMBING.COM