Home > Design & Install > Tapping Into The Main Line

In this video, we’ll be covering how to tap into the mainline and install a backflow prevention device. Before you start digging, make sure you have obtained all the required permits for tapping into your water supply mainline.

Prepare The Site For An Easy Sprinkler System Installation

After locating your sprinkler head and valve locations, use some marking spray to signify the location of your trenches. As you’ll see in the video above, marking flags have already been placed to indicate where spray heads and valves will be located. The best practice is to tap into your main water supply line close to the water meter so you’ll get the highest amount of water volume and pressure to supply your sprinkler system.

Steps To Turn Off Your Mainline

First things first, turn off the water supply at the water meter before cutting your home’s water supply line. The irrigation system will tee off of the main water supply line into a one-inch pipe that will run to the backflow prevention device [and from there to the front and back yard].

Next, cut the supply pipe, add primer, and submit to one side of the tee. Then, push on the tee fitting and twist it at a 45-degree upward angle. About five feet of service line has been dug up after the tee so that the technician can flex the PVC pipe back into the tee fitting.

Reasons Why You Need A Ball Valve In Your Irrigation System

Installing a ball valve allows you to turn off the water to the sprinkler system without interrupting your home’s water usage. After installing the ball valve, water can be restored to the house. With the ball valve closed, turn on the water at the water meter and leave a hose bib open to bleed out air trapped in the pipes during the installation.

You’ll need to install some type of backflow prevention in your system. Sprinkler Warehouse does not recommend the use of an anti-siphon valve. It’s possible for an anti-siphon valve to get stuck allowing contaminated water to get into your drinking water. Instead, we recommend a dedicated testable backflow prevention device like a PVB.

How The Pressure Vacuum Breaker Works

Here’s how the water flows through the pressure vacuum breaker. First, water travels from the ground straight up into the pressure vacuum breaker. Then, from the PVB the water heads out horizontally then makes a 90-degree turn, and back down to the ground where it will head off to the valves in your sprinkler system.

The contractor has dug a large hole giving him plenty of room to work that will allow him to easily install the backflow preventer right up next to the concrete foundation of the home. The system is using the popular Febco 765-1 pressure vacuum breaker (PVB) available at Sprinkler Warehouse.

Guide To Installing Your PVB

The technician starts by cutting into the schedule 40 PVC supply line running directly from the ball valve we just installed. He cuts the length of the pipe that will allow him to place the PVB next to the home.

Now he’s estimating the working height of the PVB. Remember, it will need to be at least 12 inches above the system’s highest sprinkler head. Next, he’s installing the upright supply pipe and double-checking the working height of the backflow prevention device, and gluing it in place.

Then, he’s cutting the outflow pipes and attached them to the PVB. Wiping away excess glue not only makes for a clean professional-looking install but also prevents the chemical reaction of the primer and cement from weakening the PVC piping.

This is the outflow piping that’s being installed now. Don’t wait for winter to wrap the above-ground PVC piping with insulation. If you take care of it when installing your system you won’t be caught off guard and besides, it’s no fun to do this while your hands are freezing. Check out our video Winterizing Your PVB located on for more information.

Run A Test To Ensure Your Sprinkler System Runs Smoothly

Once the rest of the sprinkler system is installed and you’re ready to turn on the water for the first time, to avoid damaging your piping first open both test cocks and close the downstream valve on your PVB then, slowly open the ball valve. Once water is flowing out of the test cock close the inflow PVB valve and close the test cock valves. Open the inflow valve again fully charging the PVB with water. Now, very slowly open the outflow valve allowing all of the air to be forced out of your sprinkler system.

Learn More At Sprinkler Warehouse

Remember Sprinkler Warehouse has everything for your irrigation needs to trees, lawn, flowerbeds, and gardens are lush and beautiful. If you have any questions, chat with one of our amazing customer service experts on They really know their stuff and they will get you squared away. Subscribe to our YouTube channel for more helpful tips, tutorials, and general sprinkler instruction. Sprinkler Warehouse where we offer professional quality at rock-bottom prices.