THE GARDEN SAGE / HOMEOWNER LEARNING SERIES

Inside your irrigation.

Understand the whole system. See how every part works.

Start with the whole system. Follow the water.
Then explore each part and see how it works.

01 / THE COMPLETE SYSTEM

One supply. Many carefully timed jobs.

Start here: follow the blue water path.
Select a numbered part to explore it below.

System map: public supply, meters, shutoff, backflow preventer, pressure reducer, zone valves, sprinklers and controller wiring

EXPOSED SYSTEM VIEW Pipes normally run underground

Drag to explore · Select a numbered part to inspect itTwo fingers to explore · Tap a number to inspect

Water supply & flow Station + common wiring Areas watered separately

Zone 1 is watering. The other zone valves are closed.

→→→→→

Two meters share the public supply. Irrigation water passes through its own meter without passing through the house meter.

Illustrative layout. Pipe depths, lengths, component sizes and spacing are not to scale. Backflow type, regulator position and component order depend on the approved design. Some systems also have a master valve. This guide does not operate your actual irrigation.

The controller calls.

A program sends a low-voltage command to one station. A rain sensor or weather adjustment may prevent the cycle.

The valve responds.

The solenoid changes pressure inside the valve. The diaphragm lifts, opening that zone to the water supply.

The landscape receives.

Pressure raises the sprinkler stems. Their nozzles distribute water while the other zones remain closed.

The next zone takes over.

The command ends and the valve closes. The next station runs, or the controller returns to standby.

02 / THE COMPONENT LAB

A closer look changes everything.

Seven working models. Three ways to see them.

Reference cutaway showing two independent checks in a backflow preventer

Preparing your 3D model…

3D COMPONENT EXPLORER

Drag to rotate · Scroll to zoomTwo fingers to rotate · Pinch to zoom

Recognize the part as it appears in a real system.

03 / PROTECT

The backflow preventer

Two independent checks help prevent irrigation water from returning toward the drinking-water supply.

CHANGE THE CONDITIONS

Forward flow

Water pressure opens both checks toward the irrigation side.

Choose Cutaway to see the internal mechanism.

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This is the static edition of the guide. Enable JavaScript for interactive 3D views, or open each component lesson below.

The irrigation meter

Records the volume of water delivered to irrigation. It helps distinguish outdoor use from household use and makes changes in consumption easier to investigate.

Water moves a measuring element. This representative multi-jet meter directs water against an impeller. Other meters use a nutating disc or electronic measurement instead.

Movement becomes a total. The measuring mechanism drives a register. A magnetic coupling can transmit movement through a sealed barrier, keeping the dial mechanism dry.

The reading accumulates. The register totals water volume. It does not measure pressure or decide when sprinklers should run.

At home: Usually a numbered meter in a utility box near the property boundary. Match the serial number and displayed units to the water account.

Read the meter without disturbing utility seals or operating utility-owned valves. A meter alone is not the required irrigation backflow assembly.

The irrigation shutoff

Isolates the irrigation supply independently of the electrical controller. The illustrated quarter-turn ball valve physically closes the water passage.

A hole passes through the ball. In the open position, the ball’s bore lines up with the inlet and outlet, giving water a continuous passage.

The handle turns the stem. A quarter-turn rotates the ball 90 degrees. The handle normally follows the direction of its bore.

Seats seal against the ball. Closed, the solid side of the ball faces the pipe. Seats on either side form the water seal; stem seals prevent leakage around the handle shaft.

At home: A lever on a brass valve body, often near the meter or backflow assembly. Confirm which customer-owned valve serves irrigation before operating it.

Closing the supply does not drain the system or prove it is depressurized. Do not loosen pressurized fittings or force a seized valve.

The backflow preventer

Opposes water returning from irrigation toward the supply. This model demonstrates a double-check assembly with two independent spring-loaded poppets.

Forward pressure opens the checks. Enough forward pressure difference lifts each poppet from its seat against its spring. Water passes through both checks in sequence.

The springs return the seals. As the forward pressure difference falls, the springs urge the poppets back onto their seats. A reverse pressure difference helps hold them closed.

Each check can be tested. Test ports provide access for a qualified tester to assess the checks. A clean appearance does not establish that either seal is holding.

At home: The supplied Wilkins 950XLT reference has two angled access covers, end shutoffs and test ports. Its check elements translate away from their seats; they are not hinged flaps.

This is a representative mechanism, not certified product CAD or a substitute for a backflow test. Never bypass the assembly.

The pressure reducer

Reduces excessive supply pressure to a useful downstream level. It adjusts a restriction automatically as conditions change; it cannot increase a weak supply.

The spring requests an opening. The adjustment spring acts on the diaphragm and stem, tending to open the valve. Its preload establishes the target pressure range.

The outlet provides feedback. Downstream pressure acts on the diaphragm against the spring. Rising outlet pressure moves the valve toward its seat and reduces the opening.

The forces find a balance. When downstream demand lowers pressure, the opening increases. Real regulation varies with the valve’s operating limits, available inlet pressure and flow demand.

At home: Commonly a brass body with a spring bonnet and adjustment screw. This example is a direct-acting mainline pressure-reducing valve, not a small flow-only drip regulator.

Do not use these example numbers to adjust your installation. A regulator is neither a pump nor an approved backflow assembly.

The controller

Schedules the valves electrically. Water stays in the piping; only control wiring connects this conventional controller to the valve solenoids.

A station is selected. At a scheduled or manual start, the controller energizes that station’s output. Typical conventional valves use approximately 24 volts AC.

A circuit reaches the coil. A station wire connects to one solenoid lead. Its other lead connects to the shared common, completing the control circuit.

The valve does the hydraulic work. The coil opens a small pilot passage inside the valve. Water pressure then lifts the main diaphragm; the controller does not pump water.

At home: A wall-mounted cabinet with stations, programs and run times. The field terminals normally include numbered stations and a shared C or COM connection.

The highlighted wires show the selected circuit, not one-way DC current. Do not confuse low-voltage field terminals with the cabinet’s mains power connections.

The zone valve

Connects the pressurized irrigation supply to a particular group of heads. This model uses a small electrically operated pilot to control a larger diaphragm.

Closed: the upper chamber fills. With the pilot port shut, a small metering passage admits inlet water above the diaphragm. Chamber pressure and the closing spring hold the main seal on its seat.

Open: the pilot relieves pressure. The energized solenoid lifts its small plunger. A pilot passage allows water above the diaphragm to escape toward the outlet, lowering upper-chamber pressure.

Inlet pressure lifts the diaphragm. The resulting pressure difference raises the main seal. When the pilot shuts again, the upper chamber refills and the diaphragm reseats.

At home: Usually in a ground-level valve box. Look for a molded valve body, bolted bonnet, wire-connected solenoid and a separate pipe leaving for the zone.

Do not remove a bonnet or solenoid while the system is pressurized. Turning the controller off is not a substitute for isolating the water supply.

The pop-up sprinkler

Raises a nozzle above ground and distributes water over its intended area. This model shows a stationary spray nozzle, not a rotating rotor.

Pressure raises the riser. Water entering the body pushes the riser upward against its return spring. The upper wiper seal seals around the moving stem.

The nozzle shapes the spray. Water travels through the hollow riser and filter to the nozzle. The opening shapes the spray pattern; its illustrated reach is not a coverage calculation.

The spring brings it home. When supply pressure falls, the spring extends and retracts the riser into the body. An optional check valve can limit low-head drainage.

At home: A round cap near ground level when idle, with a stem that rises during watering. The nozzle, body height and spray pattern vary between models.

A retracted head does not mean the entire system is drained or winterized. Do not pull parts apart under water pressure or spring tension.

Representative teaching models, built to explain the mechanism. Exterior details and internal geometry vary by manufacturer; these are not exact manufacturer CAD, installation drawings, or hydraulic simulations. Blue particles indicate flow direction.

UNDERSTAND THE MECHANISM

How the checks do their job.

03 / WHY A SECOND METER?

Garden water takes
a different path.

A sink sends water to a drain.
Your sprinklers send it into the landscape.

A dedicated meter makes outdoor use visible. Where your utility allows it, that measurement can keep eligible irrigation water out of the volume used to calculate sewer charges. You still pay for the water.

Installation, service fees, water rates and backflow testing affect the total cost. A second meter does not automatically guarantee savings or a sewer credit.

Separate measurement does not mean extra pressure.

A meter measures volume. Water-supply pressure and the system’s hydraulic design determine how much flow is available.

SEPARATE SERVICE

Two meters.
Two measured branches.

Public main → House meter + irrigation meter

Each meter records only its own branch. The irrigation service can have its own account and billing treatment. The branches split before the meters or use separate utility taps.

APPROVED SUBMETER

One total.
A measured garden share.

Main meter → House + irrigation submeter

The main meter counts everything first. The submeter measures the irrigation portion already included in that total. Any sewer deduction needs the provider’s approval and reporting process.

A SUBMETER EXAMPLE · VOLUME, NOT A BILL ESTIMATE

10,000gallons through the main−4,000gallons to irrigation=6,000gallons of household use

Do not add the submeter reading to the main reading. The garden’s water has already passed through the main meter.

04 / KNOW YOUR OWN SYSTEM

Four things worth locating.

You do not need to dismantle anything to understand your irrigation. Start with a simple map of your property.

Ask The Garden Sage for help ↗

01
Your customer irrigation shutoff.
Identify the accessible valve that isolates irrigation. The controller’s OFF setting does not remove supply pressure. Leave utility-owned valves and seals alone.
02
Your meter and its account.
Match the serial number to your bill. Confirm whether it is a separate service or an approved submeter, and check the reading units.
03
Your backflow assembly.
Record the model and testing information. Your provider determines the approved protection and testing requirements. Never bypass the assembly.
04
Your controller and valve boxes.
Label each station with the area it waters. Mark the valve boxes on your map and keep their lids accessible.

WHEN SOMETHING DOES NOT SEEM RIGHT

Understand the symptom.

The controller is off. Why is the meter still moving?

Supply pipes can stay pressurized even when stations are off. Continued movement on a dedicated irrigation meter after the system settles can indicate a leak, a valve passing water, or another connection. A house main meter can also move because water is being used indoors.

Why does a zone keep watering after its time ends?

A valve may be obstructed, damaged, or held open manually. Removing its electrical signal cannot close a mechanically stuck valve. If needed, close the identified customer irrigation shutoff and arrange service. Do not open a pressurized valve or backflow assembly.

Can the pressure reducer fix weak sprinkler coverage?

A reducer limits excessive pressure; it cannot create pressure or water volume. Weak coverage may involve a leak, restriction, oversized zone, inadequate supply or incorrect nozzle. Pressure measured while water is flowing can differ from static pressure.

Is the pictured double-check preventer correct for every property?

No. The supplied Wilkins 950XLT reference is a double-check assembly for low-hazard protection. The approved backflow type depends on the utility and hazard. A reduced-pressure assembly has a relief zone, and vacuum breakers have different operating and installation requirements.

Does turning the controller off winterize the system?

No. Water remains in many pipes and components. Seasonal shutdown and winterization need to match the actual installation and local conditions. Arrange system-specific service.

THE SOURCES BEHIND THE MODELS

Built around how the equipment works.

Manufacturer literature and utility guidance inform these explanations. Use the documentation for your installed model and your provider’s requirements for service decisions.

Inside your irrigation.

One supply. Many carefully timed jobs.

The controller calls.

The valve responds.

The landscape receives.

The next zone takes over.

A closer look changes everything.

The backflow preventer

Forward flow

How the checks do their job.

Garden water takesa different path.

Two meters.Two measured branches.

One total.A measured garden share.

Four things worth locating.

Your customer irrigation shutoff.

Your meter and its account.

Your backflow assembly.

Your controller and valve boxes.

Understand the symptom.

Built around how the equipment works.

Garden water takes
a different path.

Two meters.
Two measured branches.

One total.
A measured garden share.