Underground lawn and landscape irrigation systems may seem complex, but the principles by which they operate are fairly simple, and understanding a little about the system will help you understand the problems that can occur. With rare exception, most homeowners will find it possible to repair these problems themselves, but the first step is to identify the source of the problem—and this begins with understanding the components and how they work together.
Before You Begin
An in-ground lawn sprinkler system consists of several key components. In the typical system, a water supply pipe from the main water source first passes into a valve box set at ground level, where it is divided into individual underground irrigation zones, each controlled by its own zone valve. The zone valves are governed by an electronic controller, which sets the time and duration of each watering session via low-voltage wires. Smaller homes may have just one irrigation zone, but most have two, three, or more.
The zone valves themselves consist of a diaphragm that controls the flow of water; the diaphragm is open and closed based on signals received by a solenoid mounted on the zone valve. The solenoid controls a spring-loaded metal piston that opens or closes the water port passing through the valve. Irrigation zone valves come in many shapes and configurations, including models that integrate an anti-siphon device. In other systems, the anti-siphon valve is a separate device that is installed on the water pipe before it reaches the valve box.
When a zone valve opens, water flows through underground plastic tubing to feed sprinkler heads that pop up and distribute water to the lawn and landscape for however long the controller allows the zone valve to remain open.
Problems with an irrigation system typically make themselves evident with several common symptoms:
- Individual sprinkler heads not working
- Low water pressure at the sprinkler heads
- Sprinkler zones do not turn on
- Leaking around a zone valve
- Leak at the sprinkler head furthest from the valve
Source: The Spruce