Understanding the Workings of a Reticulation System

A residential reticulation system (also known as an irrigation system) is an automatic network of underground pipes, valves, and emitters (like sprinklers or drippers) designed to distribute water efficiently and consistently to a property's lawn and garden beds.

The system is generally divided into zones to account for the different watering needs of the lawn and garden beds, as well as the water pressure limitations of the property.

How the System Works

The reticulation system operates based on a few core components:

1. Water Source Connection

  • A licensed plumber typically installs a connection, or "cut-in," to the main water supply line of the house.

  • A backflow preventer (like a dual check valve) is mandatory to ensure that water from the irrigation system cannot flow backward and contaminate the home's drinking water supply.

  • A master valve (solenoid) is often installed at this point, which acts as the main shut-off for the entire reticulation system, preventing the pipes from being under constant pressure and reducing the risk of leaks when the system isn't running.

2. The Controller (The Brain)

  • The controller (or timer) is a programmable device, often mounted on an exterior wall.6 It's the "brain" of the system, allowing the homeowner to set watering schedules (start time, run time, and days) for each individual zone.

  • Modern systems can use Wi-Fi-enabled smart controllers that connect to local weather data or use soil moisture sensors to automatically adjust watering schedules, maximizing water efficiency.

3. Solenoid Valves and Zoning

  • The system is divided into different zones (e.g., front lawn zone, back garden bed zone, side lawn zone). This is crucial because different areas have different needs (lawn needs more water than a native garden) and to manage the available water flow and pressure.

  • A solenoid valve is installed for each zone. The controller sends a low-voltage electrical signal to the valve, causing it to open and allow water to flow into that specific zone's piping network. When the set run time is over, the controller signals the valve to close.

  • These valves are typically housed in an underground valve box for protection and easy access.

4. Water Distribution (Piping and Emitters)

  • Pipes (usually PVC or Polyethylene/Poly pipe) are buried underground to route the water from the solenoid valves to the various zones.

  • Emitters are the devices that actually apply the water:

  • For Lawns: Pop-up sprinklers are used. These are flush with the ground when off but "pop up" when the system is pressurized to spray water. They are installed strategically to ensure "head-to-head coverage," where the spray from one sprinkler reaches the next, ensuring even watering across the entire lawn area.

  • For Garden Beds: Drip irrigation (or subsurface dripline) or micro-sprays/bubblers are preferred. Drip systems are highly efficient, delivering water directly to the plant's roots through small emitters or porous tubing, minimizing water loss from evaporation or runoff.

Installation Overview

Installing a reticulation system involves several key steps:

1. Planning and Design

  • Map the Area: A scaled drawing of the property is made, marking the house, driveways, garden beds, and lawn areas.

  • Test Water Flow and Pressure: A bucket test determines the available water flow rate (L/min) and a pressure gauge determines the water pressure (PSI). These figures are critical for designing the system and determining how many sprinklers can run simultaneously in a single zone.

  • Zone Layout: The plan is divided into zones, ensuring that areas with similar water needs are grouped together and the total flow required for any single zone does not exceed the maximum flow rate.

2. Trenching and Piping

  • Trenching: Shallow trenches (usually 200mm deep) are dug in the lawn and garden areas following the planned pipe routes.

  • Pipe Installation: Mainline pipes are laid from the water source to the valve boxes, and secondary pipes (lateral lines) are run from the valve boxes to the emitter locations in each zone.

  • Connections: All pipes and fittings are glued (PVC) or clamped (Poly pipe) to ensure a watertight system.

3. Valve and Controller Setup

  • Solenoid Valves: Valves are installed in the valve boxes, connecting the mainline to the lateral lines for each zone.

  • Wiring: Low-voltage wires are run from the controller to each solenoid valve, typically bundled with the pipes or in a separate conduit.

  • Controller Installation: The controller is mounted and wired to the power source and the solenoid valves.

4. Emitter Installation and Testing

  • Emitters: Pop-up sprinklers are connected to the pipes via flexible or articulated risers in the lawn areas, positioned to achieve full coverage. Drip lines or micro-sprays are installed in garden beds.

  • System Test: The trenches are left open, and the system is tested zone by zone for leaks, proper water coverage, and correct pressure.

  • Backfilling: Once all checks pass, the trenches are backfilled with soil, concealing the entire system.