How to Design a Lawn Irrigation System: Complete DIY Guide

Designing a lawn irrigation system isn’t simply a matter of putting a few sprinklers around the lawn and connecting them to a garden tap.

A properly planned irrigation system needs to consider:

Water pressure
Available flow
Lawn dimensions
Sprinkler radius
Sprinkler spacing
Nozzle selection
Pipe size
Pressure loss
Number of irrigation zones
Solenoid valves
Controller capacity
Soil and slope
Watering requirements

Getting these things right before you start digging can save a considerable amount of time and money.

In this guide, we’ll walk through the basic process of designing a residential lawn irrigation system, from measuring your water supply to choosing sprinklers and planning irrigation zones.

What Does a Lawn Irrigation System Include?

A typical automatic lawn irrigation system may include:

Water supply

↓

Isolation/backflow components where required

↓

Main irrigation pipe

↓

Solenoid valves

↓

Zone pipe

↓

Pop-up sprinklers

↓

Sprinkler nozzles

The solenoid valves are connected to an irrigation controller.

The controller automatically opens each valve according to your programmed watering schedule.

Instead of trying to operate every sprinkler at once, the property is usually divided into separate irrigation zones.

Step 1: Draw a Plan of Your Property

Before buying irrigation equipment, create a basic drawing of the property.

It doesn’t need to be architectural quality.

You simply need an accurate representation of the areas you want to irrigate.

Include:

House
Lawn
Garden beds
Driveway
Footpaths
Decking
Fence
Trees
Water connection
Outdoor tap
Proposed controller location
Proposed valve location

Measure the important dimensions.

For example:

Front lawn: 8 m × 5 m

Back lawn: 12 m × 8 m

Side lawn: 2 m × 15 m

Write these measurements directly onto your drawing.

Step 2: Divide the Property Into Irrigation Areas

Different areas often require different irrigation methods.

For example:

Lawn

May use:

Spray nozzles
Rotary nozzles
Rotors

Garden beds

May use:

Drip irrigation
Dripline
Micro irrigation

Large lawn

May use:

Rotors
Longer-radius rotary nozzles

Avoid putting everything on one irrigation zone simply because it is convenient.

Different areas can have very different watering requirements.

Step 3: Measure Your Available Water Flow

This is one of the most important steps.

Your irrigation system cannot use more water than your water supply can reliably provide.

Flow is commonly measured in:

Litres per minute — L/min

A simple residential flow test can be performed using a container of known volume and a stopwatch.

For example, suppose you have a:

9-litre bucket

and it fills in:

20 seconds

Use:

Bucket volume ÷ fill time × 60

So:

9 ÷ 20 × 60

27 L/min

Your measured flow is approximately:

27 litres per minute.

Bucket Test Formula

Use:

Flow (L/min) = Container litres ÷ Seconds to fill × 60

Example 1

10 L bucket

20 seconds

10 ÷ 20 × 60 = 30 L/min

Example 2

9 L bucket

30 seconds

9 ÷ 30 × 60 = 18 L/min

Example 3

20 L container

40 seconds

20 ÷ 40 × 60 = 30 L/min

Repeat the test several times to get a more useful indication.

Remember that available flow can vary depending on the water supply and other water use occurring at the property.

Step 4: Check Your Water Pressure

Flow and pressure are not the same thing.

This is extremely important.

Flow

Measured in:

L/min

Flow tells you how much water is available.

Pressure

Commonly measured in:

kPa

Pressure affects how irrigation equipment performs.

You can have:

good pressure but insufficient flow

or:

good flow but insufficient pressure.

Both matter.

Static Pressure vs Dynamic Pressure

You may encounter two pressure measurements.

Static pressure

Pressure when water isn’t flowing.

Dynamic pressure

Pressure while water is flowing.

For sprinkler design, operating conditions matter.

A pressure gauge can help you understand your water supply.

The sprinkler manufacturer’s performance charts should then be used to determine expected radius and flow at the intended operating pressure.

Step 5: Choose Your Sprinkler Type

Now you can start selecting sprinklers.

For residential lawns, the main options include:

Traditional spray nozzles

Often suitable for smaller areas and shorter distances.

Rotary nozzles

Products such as Hunter MP Rotators can be useful for small-to-medium lawn applications where their radius and application characteristics suit the design.

Rotors

Often used for larger lawns requiring longer throw distances.

The correct sprinkler depends on:

Required radius
Pressure
Flow
Lawn shape
Sprinkler spacing

Spray vs MP Rotator vs Rotor

Type	Typical Use	Coverage
Spray nozzle	Small lawns	Short
MP Rotator / rotary nozzle	Small–medium lawns	Short–medium
Rotor	Medium–large lawns	Medium–long

These are general categories.

Always check the manufacturer’s specifications for the exact sprinkler or nozzle you’re considering.

Step 6: Determine the Required Sprinkler Radius

Look at your lawn drawing.

Measure the distance between proposed sprinkler locations.

For example, suppose the lawn is:

6 m × 6 m

If sprinklers are positioned at the corners, they need to provide appropriate coverage across that area.

You shouldn’t simply select the sprinkler with the longest advertised radius.

You want the radius to match the actual design.

Too short:

Dry areas

Too long:

Overspray

The goal is appropriate coverage without unnecessarily watering:

Driveways
Footpaths
Buildings
Fences

Step 7: Design for Head-to-Head Coverage

This is one of the most important principles in lawn sprinkler design.

Head-to-head coverage means one sprinkler reaches the next sprinkler.

Imagine:

Sprinkler A → Sprinkler B

and:

Sprinkler B → Sprinkler A

Sprinklers shouldn’t be positioned so their spray patterns barely meet in the middle.

Proper overlap helps compensate for the fact that sprinkler distribution isn’t perfectly uniform across the entire radius.

Why Sprinkler Overlap Matters

Poor sprinkler spacing can create:

Dry patches
Brown grass
Uneven growth
Overwatering near sprinkler heads
Underwatering between sprinklers

A common mistake is trying to solve poor coverage by increasing runtime.

But if the sprinkler layout is wrong, longer watering can simply make the wet areas wetter while the dry areas remain under-watered.

Fix the coverage first.

Step 8: Position Sprinklers Around the Lawn

Start with corners.

For a simple rectangular lawn, you may use:

Corners

Approximately:

90°

Along edges

Approximately:

180°

Interior locations

Where necessary:

360°

The exact arc depends on the sprinkler and the shape of the lawn.

The objective is to keep water inside the intended irrigation area.

Example: Rectangular Lawn Layout

Imagine a:

10 m × 6 m

lawn.

A possible conceptual layout might include sprinklers positioned around the perimeter with appropriate overlap.

You might use:

90° nozzles at corners

and:

180° nozzles along edges

depending on the sprinkler radius.

Don’t automatically put one sprinkler in each corner and assume the lawn will be covered.

Check the actual radius and overlap.

Step 9: Choose the Correct Sprinkler Arc

The arc describes how much of a circle the sprinkler waters.

90°

Quarter circle.

Often used at corners.

180°

Half circle.

Often used along edges.

360°

Full circle.

Often used in central lawn areas.

There are also adjustable and specialty patterns available.

Don’t Water the Driveway

Overspray is one of the easiest irrigation problems to avoid during the design stage.

If your sprinkler is watering:

Grass + driveway

you’re using water outside the intended area.

Choose the appropriate:

Arc
Radius
Sprinkler location
Nozzle

Design around the actual lawn shape.

Step 10: Find the Flow Rate of Each Sprinkler

Once you’ve selected the sprinkler/nozzle, check its flow rate.

The manufacturer will normally provide a performance chart showing:

Pressure
Radius
Arc
Flow

For example, suppose your proposed sprinklers use:

Sprinkler 1 = 4 L/min

Sprinkler 2 = 4 L/min

Sprinkler 3 = 4 L/min

Sprinkler 4 = 4 L/min

Total zone flow:

16 L/min

Now compare that with your available water supply.

Step 11: Don’t Use 100% of Your Measured Flow

Suppose your bucket test shows:

30 L/min

It isn’t usually a good idea to design a zone requiring exactly:

30 L/min

under all conditions.

Real systems have:

Pressure loss
Pipe friction
Fittings
Valves
Elevation changes
Supply variation

You need to design with operating pressure and hydraulic losses in mind.

The bucket test is useful, but it isn’t a complete hydraulic calculation.

Step 12: Calculate the Flow for Each Zone

Let’s say your sprinkler flow requirements are:

Sprinkler A

5 L/min

Sprinkler B

5 L/min

Sprinkler C

4 L/min

Sprinkler D

4 L/min

Total:

18 L/min

If your water supply can reliably support that demand at the required operating pressure, these sprinklers may potentially operate together.

If not, divide them into additional zones.

Step 13: Divide the System Into Zones

An irrigation zone is a group of sprinklers operating at the same time.

For example:

Zone 1

Front lawn

Zone 2

Back lawn

Zone 3

Side lawn

Zone 4

Garden dripline

The controller runs each zone separately.

This allows a limited water supply to operate a larger irrigation system.

Why Irrigation Zones Are Important

Suppose the entire property contains sprinklers requiring:

60 L/min

but your available supply can only support approximately:

25 L/min

You can’t simply run everything simultaneously.

Instead:

Zone 1 = 20 L/min

Zone 2 = 22 L/min

Zone 3 = 18 L/min

The controller operates them one at a time.

This is the basic concept behind irrigation zoning.

Don’t Mix Incompatible Irrigation Types

Avoid randomly placing different irrigation technologies on the same zone.

For example:

Traditional spray nozzles

and:

MP Rotators

can have different application rates.

Similarly:

Lawn sprinklers

and:

garden dripline

often have completely different watering requirements.

Where practical, keep irrigation methods with different watering characteristics on separate zones.

Step 14: Choose Your Irrigation Pipe

Poly pipe is commonly used in residential irrigation systems.

Common sizes may include:

13 mm
19 mm
25 mm

The appropriate pipe size depends on:

Required flow
Pipe length
Pressure
Number of sprinklers
Fittings
System design

Do not choose pipe size solely based on which option is cheapest.

Why Pipe Size Matters

As water moves through pipe, pressure is lost due to friction.

Generally:

Higher flow + smaller pipe + longer distance = greater friction loss

This can reduce the pressure available at the sprinklers.

Symptoms may include:

Sprinklers not reaching their radius
Weak pop-ups
Poor rotor performance
Uneven watering

Pipe sizing is part of the hydraulic design.

13mm vs 19mm vs 25mm Irrigation Pipe

13mm

Can be useful for smaller-flow applications and certain lateral connections.

19mm

Used in various residential irrigation applications depending on flow and distance.

25mm

Commonly useful where larger flow or longer runs require lower friction loss.

There is no universal rule saying:

“Use 19mm for every home.”

Calculate the system requirements.

Step 15: Plan Your Mainline and Lateral Pipe

There are generally two concepts to understand.

Mainline

Carries water toward the irrigation valves or through continuously pressurised parts of the system depending on the design.

Lateral / zone pipe

Carries water from a valve to the sprinklers in that irrigation zone.

Plan pipe routes before trenching.

Try to avoid unnecessarily complicated routes.

Step 16: Choose Solenoid Valves

Each automatic irrigation zone generally requires a solenoid valve.

For example:

4 irrigation zones

Typically:

4 zone valves

The valves connect to the irrigation controller using irrigation cable.

When the controller activates:

Zone 1

the corresponding valve opens.

When Zone 1 finishes, it closes.

Then:

Zone 2

can operate.

What Size Solenoid Valve Do You Need?

Valve sizing depends on:

System flow
Pipe size
Pressure
Manufacturer specifications

Residential irrigation systems commonly use valves sized to suit the associated pipework and hydraulic requirements.

Don’t assume that a larger valve automatically improves the system.

Use the valve manufacturer’s flow and pressure-loss specifications.

Step 17: Plan Your Valve Box

Solenoid valves are often installed inside an irrigation valve box.

This allows access for:

Maintenance
Solenoid replacement
Valve servicing
Wiring
Manual operation

Avoid burying valves directly where they become difficult to locate.

Future you will appreciate having accessible valve boxes.

Step 18: Choose an Irrigation Controller

Your controller needs enough stations for the number of irrigation zones.

For example:

4 zones

You need at least:

4 stations

6 zones

You need at least:

6 stations

But consider future expansion.

If you currently need:

5 zones

buying a controller with additional capacity may make sense if you expect to add irrigation later.

Smart vs Traditional Irrigation Controllers

Traditional controllers generally use programmed schedules.

Smart controllers may add features such as:

Wi-Fi
Smartphone control
Weather information
Seasonal adjustment
Remote operation
Alerts

Examples of irrigation controller ecosystems include products from:

Hunter
Rain Bird

Choose based on the features you actually need.

Step 19: Decide Where the Controller Will Be Installed

Before installation, consider:

Power availability
Indoor vs outdoor rating
Wi-Fi signal if required
Distance from valves
Cable routing
Accessibility

Don’t choose the controller location after all the pipework has already been installed.

Plan it as part of the system.

Step 20: Plan Irrigation Cable

Automatic solenoid valves require wiring back to the controller.

Typically, the design requires:

Common wire
Individual station wires

The exact wiring depends on the controller and valve system.

Use irrigation cable suitable for the installation environment and follow the manufacturer’s instructions.

Electrical work must comply with applicable requirements.

Step 21: Consider Water Pressure Loss

Pressure available at the water source isn’t necessarily the pressure available at the final sprinkler.

Pressure can be lost through:

Pipe
Valves
Filters
Fittings
Backflow equipment
Elevation
Long pipe runs

For example:

Source pressure

↓

Valve loss

↓

Pipe friction

↓

Fittings

↓

Sprinkler operating pressure

Your goal is to ensure sufficient pressure remains at the sprinkler.

Step 22: Consider Elevation

Water moving uphill affects pressure.

If one lawn area is significantly higher than the water source, the irrigation design should account for elevation.

Likewise, downhill irrigation can create other issues such as low-head drainage after a zone shuts off.

For properties with significant elevation changes, hydraulic calculations become increasingly important.

Step 23: Consider Soil Type

Irrigation isn’t just about the sprinkler.

The soil needs to absorb the water.

Sandy soil

Often drains relatively quickly.

Clay soil

May absorb water more slowly and can be prone to runoff.

Loam

Often has more balanced infiltration characteristics.

Your irrigation schedule should reflect the actual site.

Step 24: Consider Lawn Slope

Sloping lawns can experience runoff.

If water is applied faster than the soil can absorb it, water may travel downhill instead of soaking into the root zone.

Possible approaches include:

Lower application rates
Appropriate nozzle selection
Cycle-and-soak scheduling
Correct sprinkler placement

What Is Cycle and Soak?

Instead of running a zone continuously for:

30 minutes

you might divide watering into:

10 minutes

pause

10 minutes

pause

10 minutes

This gives the soil additional time to absorb water between cycles.

Whether this is appropriate depends on the site.

Step 25: Check Your Sprinkler Coverage on Paper

Before digging, review the plan.

Ask:

Does every sprinkler reach the next sprinkler?

Are there dry gaps?

Are sprinklers watering concrete?

Is the radius appropriate?

Are arcs correct?

Is each zone within available flow?

Is pipe size appropriate?

Fixing a design on paper is much easier than moving buried sprinklers later.

Example Lawn Irrigation Design

Let’s create a simplified example.

Property:

Front lawn: 8 m × 5 m

Back lawn: 12 m × 8 m

Garden beds around house

Available measured flow:

30 L/min

The design might become:

Zone 1

Front lawn sprinklers

Zone 2

Back lawn section A

Zone 3

Back lawn section B

Zone 4

Garden dripline

Each zone is designed to stay within the available hydraulic capacity while maintaining appropriate sprinkler pressure.

Example Zone Calculation

Suppose Zone 1 contains:

4 sprinklers

Each requires:

5 L/min

Total:

4 × 5

20 L/min

Zone 2 contains:

5 sprinklers

Each requires:

4 L/min

Total:

5 × 4

20 L/min

The controller runs:

Zone 1 first

then:

Zone 2

They don’t need to operate simultaneously.

How Many Sprinklers Can You Put on One Zone?

There is no fixed answer.

You need to calculate:

Sprinkler flow × number of sprinklers

For example:

Four sprinklers at 5 L/min

20 L/min

Six sprinklers at 5 L/min

30 L/min

Eight sprinklers at 5 L/min

40 L/min

Then determine whether the water supply and hydraulic design can support that zone at the required operating pressure.

Common Irrigation Design Mistakes

1. Buying sprinklers before designing

Design first.

Buy second.

2. Ignoring water flow

Your water supply has limits.

3. Looking only at static pressure

Operating conditions matter.

4. Too many sprinklers on one zone

This can cause weak sprinkler performance.

5. Poor sprinkler spacing

This creates dry patches.

6. No head-to-head coverage

Sprinklers need appropriate overlap.

7. Wrong sprinkler radius

Too short creates gaps.

Too long creates overspray.

8. Mixing spray and rotary nozzles without considering application rates

This can cause uneven watering.

9. Using undersized pipe

Excessive friction loss can reduce sprinkler performance.

10. Mixing lawn and drip irrigation

Different areas often require different watering schedules.

11. Forgetting future expansion

Leave room where practical.

12. Burying valves without accessible boxes

Maintenance becomes unnecessarily difficult.

Should Sprinklers Be Installed Before Turf?

Where practical, yes.

Installing irrigation before new turf allows you to:

Trench easily
Install pipe
Position sprinklers
Test coverage
Fix leaks
Adjust sprinkler height

before the lawn is laid.

It is usually much easier than cutting through newly established turf.

How Deep Should Irrigation Pipe Be?

Installation depth depends on:

Application
Local requirements
Pipe type
Vehicle loads
Landscape conditions
Manufacturer recommendations

Don’t place irrigation pipe where normal gardening or lawn work will easily damage it.

For areas subject to vehicle traffic or other loads, additional design considerations may apply.

What Sprinklers Should You Use?

A simple starting point:

Small lawn

Spray nozzles or short-radius rotary nozzles

Medium lawn

Rotary nozzles or suitable rotors

Large lawn

Rotors

Narrow lawn

Strip-pattern or suitable rotary nozzles

Garden beds

Drip irrigation

These are starting points only.

Actual selection should be based on hydraulic and coverage requirements.

Hunter MP1000 vs MP2000 vs MP3000

If you’re considering Hunter MP Rotators, the main models can be thought of by their intended radius ranges.

MP1000

Shorter-radius applications.

MP2000

Medium-radius applications.

MP3000

Longer-radius applications.

Measure the required sprinkler spacing first and then select the model using Hunter’s current performance data.

Don’t simply buy the largest nozzle.

What Size Controller Do You Need?

Count the irrigation zones.

Then consider expansion.

For example:

Current system: 5 zones

6-station controller

could operate the system.

But if you expect to add:

Another lawn
Garden drip
Vegetable garden

additional station capacity may be useful.

Do You Need a Rain Sensor?

A rain sensor can help prevent scheduled irrigation under certain wet-weather conditions.

Some smart controllers may also provide weather-based irrigation functionality.

The best option depends on:

Controller
Local conditions
System requirements

A sensor doesn’t compensate for poor sprinkler design, but it can improve how a properly designed system is controlled.

Do You Need a Filter?

Filtration can be important, particularly for irrigation equipment with small water passages.

Filters are commonly useful with:

Drip irrigation
Certain nozzles
Tank water
Alternative water supplies

Select filtration based on the water source and irrigation equipment.

Do You Need a Pressure Regulator?

Possibly.

A pressure regulator can be useful when supply pressure is higher than the operating range required by downstream irrigation equipment.

Different products have different pressure requirements.

Check the manufacturer’s specifications.

Tank Water Irrigation Design

If your irrigation system uses a rainwater tank, you also need to consider:

Pump flow
Pump pressure
Tank capacity
Filters
Suction conditions
Pipe sizing
Available stored water

Don’t assume a large pump automatically means good sprinkler performance.

The pump needs to operate appropriately at the required combination of:

flow + pressure.

Pump Selection for Irrigation

Pump selection should be based on the required system duty point.

For example, your irrigation zone may require:

25 L/min

at a particular pressure.

The pump needs to be capable of delivering that flow while maintaining sufficient pressure after system losses.

Looking only at the pump’s maximum flow rating can be misleading.

How Much Water Will Your Irrigation System Use?

Use:

Flow × Runtime

For example:

Zone flow:

20 L/min

Runtime:

20 minutes

Water consumption:

20 × 20 = 400 litres

If three zones each use approximately 400 litres:

1,200 litres

per complete watering cycle.

Understanding this before installation can help you estimate irrigation water consumption.

How Long Should You Run Lawn Irrigation?

There isn’t one universal runtime.

It depends on:

Sprinkler application rate
Soil
Grass
Weather
Season
Coverage
Local conditions

Don’t copy someone else’s controller schedule simply because they use similar sprinklers.

Your property may have completely different conditions.

DIY Irrigation Design Checklist

Before purchasing anything, confirm:

Lawn dimensions
Water source
Available flow
Available pressure
Required sprinkler radius
Sprinkler type
Sprinkler arc
Sprinkler spacing
Flow per sprinkler
Total zone flow
Number of zones
Pipe size
Pipe length
Valve size
Controller stations
Cable requirements
Soil type
Slope
Filtration
Pressure regulation
Future expansion

Frequently Asked Questions

How do I design a lawn irrigation system?

Start by measuring the property, testing water flow and pressure, selecting suitable sprinklers, planning head-to-head coverage, calculating zone flow, choosing pipe and valves, and selecting a controller with enough stations.

How many sprinklers can I put on one zone?

It depends on the available water flow, pressure, pipe size and individual sprinkler flow rates. Add the flow requirements of all sprinklers in the proposed zone and confirm the system can support them at the required operating pressure.

How far apart should lawn sprinklers be?

Spacing depends on the sprinkler’s actual radius under your operating conditions. Head-to-head coverage is an important design principle for many lawn systems.

What size irrigation pipe should I use?

Pipe size depends on flow, pipe length, pressure loss and system design. Common residential poly pipe sizes include 13mm, 19mm and 25mm, but the correct size should be selected hydraulically.

Should I use MP Rotators or spray nozzles?

It depends on the required radius, application rate, pressure, flow and lawn design. Neither is automatically best for every property.

Should I use MP Rotators or rotors?

MP Rotators are commonly suited to small-to-medium residential applications, while rotors can be better suited to larger areas requiring longer throw distances.

Do I need a separate valve for every irrigation zone?

Automatic systems generally use a separate zone valve for each independently controlled irrigation zone.

Can lawn sprinklers and drip irrigation be on the same zone?

It’s generally preferable to separate irrigation methods with significantly different application rates and watering requirements.

How do I calculate irrigation flow?

Add the flow rates of every sprinkler operating simultaneously in the zone.

For example:

4 sprinklers × 5 L/min = 20 L/min

How do I measure water flow at home?

A simple bucket test can provide an indication. Divide the container volume in litres by the seconds required to fill it, then multiply by 60.

Is pressure or flow more important for sprinklers?

Both are important. Flow determines how much water is available, while pressure affects sprinkler performance. A successful design needs sufficient flow at the required operating pressure.

Why are my sprinklers weak?

Possible causes include too many sprinklers on the zone, low pressure, insufficient flow, pipe friction, blocked filters, valve restrictions or leaks.

Can I install irrigation myself?

Many homeowners install residential irrigation systems themselves, but the difficulty depends on the property, water connection, hydraulic requirements and applicable plumbing/electrical requirements. Work requiring licensed trades should be completed accordingly.

Should irrigation be installed before new turf?

Where practical, installing and testing the irrigation system before laying turf usually makes installation and adjustment easier.

Final Lawn Irrigation Design Formula

A good irrigation system can be thought of as:

Measure

↓

Test flow

↓

Check pressure

↓

Choose sprinklers

↓

Plan head-to-head coverage

↓

Calculate sprinkler flow

↓

Create zones

↓

Size pipe

↓

Choose valves

↓

Choose controller

↓

Install

↓

Flush

↓

Test

↓

Adjust

Don’t skip the first steps and jump straight to buying equipment.

A good irrigation system is designed around the property and its available water supply.

Build Your Irrigation System With SprinklerPros

Once you’ve designed the system, you can start selecting the components required for the installation.

Depending on your design, you may need:

Pop-up sprinklers
Hunter MP Rotators
Spray nozzles
Rotors
Poly irrigation pipe
Poly fittings
Solenoid valves
Valve boxes
Irrigation cable
Irrigation controllers
Filters
Pressure regulators
Dripline
Irrigation accessories

The most important rule is:

Design before you buy.

Measure your lawn.

Check your water supply.

Calculate your zones.

Choose the correct sprinkler radius.

Plan the pipework.

Then purchase the components that match the design.

A well-designed irrigation system should provide appropriate coverage without relying on excessive watering to compensate for poor sprinkler placement.

Good irrigation starts on paper — before the first trench is dug.