DIY Network

How To Prepare for a Backflow-Prevention Device

Learn how to prepare for the installation a backflow preventer. This installation is recommended for an experienced master plumber, but preparation work can be done ahead of time.

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prepare for installing backflow preventer
  • Time

    Under Half Day

  • Price Range

    $50 - $100

  • Difficulty

    Moderate to Hard


Step 1: Dig a Hole Around the Water Meter

A backflow-prevention device safeguards the water line from the nonpotable water in the irrigation system, and in fact, this is required by many local codes throughout the country. Start by digging a hole around the water meter. A 2'-by-2' hole should be sufficient for most water mains. Carefully expose the water-main pipe and fittings, then call a professional to handle the installation.

Step 2: Attach the Device

The backflow-prevention device is threaded onto the main line and is tightened securely with a pipe wrench.

attach the device

Step 3: Attach the Master Control Valve

On the other end of the backflow preventer, the master control valve (Image 1) is threaded on using Teflon (c) tape. First cut a small piece of 1" poly pipe about 12" long. Using a stainless-steel clamp, crimp the clamp tightly down onto the control valve. Slide clamps onto the main pipe and zone pipe. Slide a T-coupler (Image 2) into the main and zone pipes and onto the control-valve pipe. Crimp all clamps down securely (Image 3). Since this is a critical junction in the irrigation system, using two clamps per section is recommended.