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Home > Plumbing > Adding a Valve to an Irrigation System

Adding a Valve to an Irrigation System

By Brett Freeman
Adding a Valve to an Irrigation System

Adding a Valve to an Irrigation System

Many people imagine that irrigation systems are much more complicated than they actually are. This may be due to the fact that nearly all of the working parts are underground. But if you understand the basics, you can save yourself thousands of dollars by adding new zones to an existing system yourself. The first step is the addition of a new valve.

The Basics

Here's the way your irrigation system works. Water, under pressure, comes into the system, usually via a tap-in to the municipal water line. Sometimes it is pumped from a well, lake, or other source. Output is controlled by valves, one for each zone of your irrigation system, which are themselves controlled by a timer. When the timer sends a low-voltage signal to a valve, the valve opens, and that zone's sprinklers turn on. So, to add a zone, you need to add a valve.

What You Need to Know

Begin by locating your valve box or boxes. These boxes are generally dark green or black, and installed with the cover at ground level. Inside are the valves attached to the pipes that carry water in and out. If there are fewer valves in the valve box than zones in your system, then there is another valve box somewhere. In general you want to add a valve to the valve box closest to where you want your new zone. The exception is when this would require you to run a pipe under a driveway or sidewalk.

Understanding the Valve Assembly

Dig out the valve box so you have adequate space to work. Generally the valves are in a row, attached to the water source line by T-joints. If the final valve attaches to the source line via a T-joint (not an elbow joint), you can fairly easily add a valve to the valve assembly. But before you do, turn off the water. If you can't find a shutoff valve, you have to turn off the main water line to your home. If your system uses a well or lake pump, cut power to the pump at the circuit breaker board.

Adding the Valve

The water source line is either capped on the far side of the final valve, or it continues to another valve box. If it is capped, cut off the cap and add another T-joint. This joint is attached to the source line on one side, the new valve in the middle, and end in a short, capped length of pipe on the other. Using PVC solvents, preassemble this new section (T-joint to valve, T-joint to short length of PVC pipe, cap to PVC pipe). Cut the cap off the pipe at the end of the existing valve assembly, and use solvents to attach the remaining leg of your new assembly's T-joint to the main line.

If the main line continues to another valve box, do the same preassembly steps as above, but instead of attaching to a length of pipe that ends in a cap on one side, it attaches to a length of pipe that ends in half of a PVC union coupling. After preassembling your new section, use it as a guide to determine how large a section of the source pipe you need to remove. Cut the section of pipe out, and attach the other end of end of the PVC union coupling to the outgoing section of the source pipe. Using solvents, attach the preassembled valve assembly extension to the source pipe where it comes out of the existing valve assembly. Pull up on the end of the pipe to slide the T-joint over the end of the pipe. Finally, screw the two ends of the PVC union coupling together.

After the solvents dry, turn the water back on. If the PVC union coupling leaks, turn the water off, tighten the coupling, and turn the water back on. Repeat until the coupling doesn't leak.

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