How much water does a lawn need?

How long and how often should you water your lawn? A simple summer watering guide for South Australian lawns, covering soil types, irrigation methods and how to keep lawns green without wasting water.

In Short

There is no single rule for how long or how often you should water your lawn. In South Australia, most warm-season lawns (couch and kikuyu) perform best with 15–32mm of water per week in summer, depending on how green, durable and “perfect” you want your lawn to be. Soil type, lawn use, irrigation method and seasonal conditions all matter—and the best results come from matching water use to your expectations.

How Long Should I Water My Lawn – and How Often?

“How long should I water my lawn?” and “How often should I water it?” are two of the most common lawn questions we’re asked—and for good reason. With persistent heat and rising water costs, people want lawns that perform well without wasting water.

The problem is that there isn’t a single, universal answer. Lawn watering is contextual. The right amount of water depends on what you expect from your lawn, what it’s growing in, and how efficiently that water is applied.

To explain this properly, it helps to lean on research rather than opinion.

Why We Reference the IPOS Code of Practice

In 2007, IPOS Consulting was engaged by the South Australian Government to develop the Irrigated Public Open Space (IPOS) Code of Practice. Its purpose was to ensure public turf areas could remain fit for use while managing water responsibly.

In simple terms, the Code provides a framework for matching turf quality expectations with efficient water use, backed by real data.

While the Code was written for professional turf managers in public spaces, many of its principles translate exceptionally well to residential lawns. That’s why I reference it here—and why later in this blog I use its lawn classification system to help answer the “how much and how often” question in a meaningful way.

Before we get there, though, there are a few fundamentals to cover.

What Do You Want From Your Lawn?

Every lawn has a purpose—even if you’ve never consciously defined it.

Some lawns exist mainly for appearance. Others are recreation spaces for kids and pets. Some are high-traffic areas, while others are largely decorative. The harder you expect a lawn to work, the faster it must grow to recover—and that means more water.

Equally important is how you want it to look. Some people are happy for their lawn to brown off or thin out during summer. Others want it dark green, dense and uniform all year round.

Neither approach is right or wrong—but they require very different water inputs. Understanding your expectations is critical before deciding how much to water.

Climate, Rainfall and Reality

Any discussion about lawn watering focuses naturally on the warmer months, when moisture stress is most likely. Even then, conditions are constantly changing.

Did it rain? How much? Was it hot? Windy? Was there a heatwave?

With climate variability—and climate change—it’s unrealistic to set an irrigation program in spring and not touch it again until autumn. Lawn watering is dynamic, not static. That’s why black-and-white answers rarely work.

Lawn Type Matters

The type of lawn you have makes a huge difference to water use.

Warm-season grasses such as couch and kikuyu use up to 50% less water than cool-season grasses like rye and tall fescue. Most lawns in South Australia fall into this warm-season category, which is why this article focuses primarily on them.

If you have a cool-season lawn, seek tailored advice before applying the recommendations here.

Soil: The Hidden Driver of Water Use

Soil type determines how water moves, how much is stored, and how accessible it is to roots.

Sandy soils hold less water but allow deeper root systems. Heavier soils hold more water but absorb it slowly. In Adelaide, sandy soils are also commonly non-wetting (hydrophobic), meaning water runs off instead of soaking in.

This is critical:
If your soil is non-wetting, it doesn’t matter how much or how often you water—your lawn will still suffer moisture stress. Regular use of liquid wetting agents is essential to prevent water wastage and turf stress.

When watering, you should aim for moisture penetration to at least 50mm deep. The only way to know if you’re achieving this is to check—either by digging a small inspection hole after watering or using a soil moisture probe.

Site Conditions Still Count

Shade reduces evaporation. Slopes increase runoff. Fences and paving radiate heat. While these factors are secondary, they still influence how much water your lawn actually needs.

How You Water Changes Everything

Well-designed pop-up irrigation systems are far more efficient than hand watering or basic hose-end sprinklers—but only if they are designed and maintained correctly.

Sprinkler choice matters too. Mini-rotator sprinklers such as Rain Bird R-VANs or Hunter MP Rotators apply water more slowly and evenly than traditional pop-ups and can significantly reduce water use. They can also be retrofitted into many existing systems.

Turning All of This Into a Simple Framework

This is where the IPOS Code of Practice becomes genuinely useful.

Rather than asking “how long should I water?”, the Code categorises lawns by intended function and quality expectations, then links those expectations to benchmark water use.

For residential lawns, most people fit neatly into one of three categories.

Lawn Watering Categories (Based on IPOS Benchmarks)

Category 1: Elite Lawns

For lawns maintained to the highest possible standard.

These lawns are expected to stay green, uniform and highly durable all year round, even during heatwaves. This category suits very high-use or appearance-critical lawns.

Approximate water use (per 100m²):

• 100,000 litres per year
• 32mm per week (average)
• Approx annual cost: $300

Category 2: High-Quality Lawns

This is where most residential lawns sit.

Lawns in this category look good year-round but may fluctuate slightly with seasons or extreme weather. Occasional thinning or patching is acceptable.

Approximate water use (per 100m²):

• 70,000 litres per year
• 22mm per week (average)
• Approx annual cost: $210

Category 3: Standard Lawns

These lawns are managed primarily for survival and basic function rather than appearance.

Colour loss and seasonal fluctuation are expected, but coverage remains acceptable with minimal input.

Approximate water use (per 100m²):

• 50,000 litres per year
• 15mm per week (average)
• Approx annual cost: $150

Important Notes

These benchmarks assume:

• Suitable soil profile
• An effective irrigation system
• No non-wetting soil issues
• Appropriate fertiliser management
• Average Adelaide metropolitan climate

Watering should always be adjusted up or down for extreme weather or site-specific conditions.

Translating Water Volumes Into Run Times

Once you’ve decided what standard you want to maintain, the next step is turning a weekly water requirement into something practical: how long to run your sprinklers and how often.

For most homeowners, Category 2 – High-Quality lawns is the goal. This category delivers a lawn that looks good year-round, stays green through summer, and performs well under normal family use—without the obsession or water use required for elite turf.

Based on the IPOS benchmarks, a High-Quality couch or kikuyu lawn in the Adelaide metro region requires around 22mm of water per week during summer, assuming efficient irrigation, suitable soil and no non-wetting issues.

How that 22mm is applied depends entirely on the irrigation method you’re using.

Traditional Pop-Up Sprinklers

Traditional pop-ups apply water relatively quickly. Because of this, the weekly water requirement can usually be delivered in a single, deep watering.

• 30 minutes per zone
• Twice per week

This assumes the system is functioning correctly and water is penetrating to depth rather than running off.

Mini-Rotator Sprinklers (MP Rotators or R-VANs)

Mini-rotators apply water more slowly and evenly, which improves infiltration and reduces runoff. Because they apply water at roughly half the rate of traditional pop-ups, they need to run longer to deliver the same amount.

• 60 minutes per zone
• Twice per week

While the run time is longer, these sprinklers are more efficient and typically use less water overall.

Subsurface Drip Irrigation

Subsurface drip systems deliver water directly into the root zone at a very slow rate. Because of this, water is best applied more frequently in shorter cycles.

• 30 minutes per zone
• Three times per week

This often feels counter-intuitive at first, but when installed and managed correctly, subsurface drip is one of the most efficient ways to water a lawn.

Moveable Hose-End Sprinklers

Hose-end sprinklers can work well, provided you’re prepared to move them around and allow enough time for deep watering.

• 30–45 minutes per area
• Twice per week, depending on sprinkler type and coverage

Uniformity is the biggest challenge with this method, so attention and patience are key.

A Final Word on Fine-Tuning

These run times are a starting point, not a rulebook. Soil type, slope, shade, wind exposure and soil wetting all influence how effective your watering will be.

To dial things in properly:

• Use catch cups to confirm how much water your system applies
• Check soil moisture after watering to ensure penetration to at least 50mm
• Adjust run times if water isn’t reaching depth or is running off

Once you’ve done this a few times, you’ll gain confidence in your system—and your watering program becomes simple, efficient and repeatable.

The Takeaway

The best lawn watering advice isn’t a number—it’s a process.

• Decide what you want from your lawn.
• Understand your soil.
• Choose efficient irrigation.
• Match water use to expectations, not habits.

Do that, and you’ll reduce waste, save money and end up with a lawn that performs exactly the way you want it to.

Frequently Asked Questions

How often should I water my lawn in South Australia?

Most warm-season lawns such as couch and kikuyu perform best with one deep watering per week in summer, or an equivalent amount spread over multiple cycles depending on the irrigation method. During cooler months, watering frequency can usually be reduced or stopped altogether.

How much water does my lawn actually need?

That depends on your expectations. Based on IPOS benchmarks:

• Standard lawns need around 15mm per week
• High-quality lawns need around 22mm per week
• Elite lawns may require 30–32mm per week
  These figures assume efficient irrigation, suitable soil and average Adelaide climate conditions.

Is it better to water deeply or more often?

Deep watering is generally better. It encourages deeper roots, improves drought tolerance and reduces water loss through evaporation and runoff. Frequent shallow watering leads to weak root systems and higher water use over time.

How do I know if I’m watering deeply enough?

After watering, dig a small inspection hole or use a soil moisture probe. Ideally, moisture should reach at least 50mm below the surface. If it hasn’t, increase run time or investigate whether your soil is water-repellent.

Why does my lawn still look dry even though I water regularly?

This is very often caused by non-wetting (hydrophobic) soil, which is common in Adelaide. When soil repels water, moisture runs off instead of penetrating to the root zone. Regular application of liquid wetting agents is essential to fix this issue.

Can I water too much?

Yes. Overwatering can lead to shallow roots, fungal disease, nutrient leaching and wasted water. The goal is not more water, but the right amount applied efficiently.

Does lawn type really make that much difference?

Yes. Warm-season grasses like couch and kikuyu use up to 50% less water than cool-season grasses such as rye and tall fescue. Most South Australian lawns are warm-season, which is why they are the focus of this article.

Are modern sprinklers really more efficient?

Absolutely. Mini-rotator sprinklers such as Rain Bird R-VANs and Hunter MP Rotators apply water more slowly and evenly than traditional pop-ups, significantly reducing runoff and overall water use. They can also be retrofitted into many existing systems.

Should I change my irrigation settings through the year?

Yes. Lawn watering should be adjusted for temperature, rainfall, wind and seasonal growth patterns. It’s unrealistic—and inefficient—to run the same program from spring through to autumn without changes.

Is the IPOS Code of Practice relevant to home lawns?

While it was written for public open space, the IPOS Code is one of the best data-driven frameworks available for matching turf performance with responsible water use. Its principles translate extremely well to residential lawns when applied sensibly.