Garden Water Savings Calculator Australia: Mulch & Drip Irrigation

See how much water and money you could save

Compare your current watering and mulching with a drip irrigation and mulch setup, using typical Australian climate figures. You can enter your own water price for a more accurate result.

Step 1: Your climate zone

Evaporation and rainfall vary hugely across Australia. Pick the zone closest to your garden. Figures are typical averages.

Step 2: Garden size and type

Different plants need different amounts of water. A vegetable patch needs far more than a native garden.

Garden type

Step 3: How do you water now?

Not all of the water you apply reaches plant roots. The percentage shown is a typical efficiency for each method.

Step 4: Your current mulch

Mulch cuts evaporation from the soil surface. The deeper the layer, the more it helps.

Step 5: Your water price

Pick your state for a typical price, then change it to match your bill. Use the price per kilolitre (kL) for the usage tier you pay. One kL is 1,000 litres.

Your estimated water savings

Yearly water used

Your current setup
With drip irrigation and mulch

The improved setup assumes drip irrigation (about 90% efficient) and a 75 mm layer of mulch.

Your water-saving action plan

This is an estimate based on typical climate figures and a simple model, not a measurement of your garden. Local water restrictions and your soil and plants will change the real numbers.

Water-smart gardening in Australia

Australia is the driest inhabited continent, and gardens can account for a big share of a household’s water use, especially in summer. The biggest water losses are usually avoidable: evaporation from bare soil, spray that never reaches roots, and watering at the wrong time of day.

Evaporation

Bare soil in hot, windy weather loses water quickly. A layer of mulch shades the surface and slows that loss.

Delivery method

Sprinklers lose water to wind and evaporation. Drip lines and soaker hoses put water at the roots, where plants can use it.

Timing

Watering early in the morning, when it is cool and calm, means less water lost before it soaks in.

Rebates and rules

Some water utilities and councils offer rebates for tanks or efficient irrigation, and many areas have watering rules. Check with your local provider.

How this calculator works

We estimate how much water your garden needs from typical evaporation and rainfall for your climate zone and the water demand of your garden type. Then we adjust for mulch and for how efficiently your watering method delivers water. These assumptions are simplified:

  • Climate figures are typical approximations for each zone, not data for your suburb.
  • About 35% of a garden bed’s water loss is assumed to be evaporation from the soil surface. Mulch reduces only that part: roughly 30% less with a light layer, 60% with 75 mm and 70% with a deep layer.
  • Efficiency figures are typical: hand hose 60%, oscillating sprinkler 50%, pop-up sprinkler 65%, watering can 80%, drip 90%, sub-surface drip 95%.
  • Rainfall is counted at 70% effectiveness, except in greenhouses and grow tents where rain doesn’t reach plants.
  • The result assumes plants are growing and watered year-round, so many gardens will use less.

Frequently asked questions

How much water does a garden use in a year in Australia?

It varies enormously with climate, plants and watering method. A 50 m² vegetable garden in a hot, dry area can use many times more water than a native garden in a cool, wet one. Evaporation, rainfall and how efficiently you deliver water are the main drivers, which is why the calculator asks for each.

Does mulch really save water?

Yes. A layer of organic mulch shades the soil and slows evaporation from the surface, so the soil stays moist longer between waterings. A depth of around 75 mm is commonly recommended for garden beds. Mulch also suppresses weeds, which compete with your plants for water.

When is the best time to water a garden?

Early morning, ideally before about 8 am. It’s cooler and calmer, so less water is lost to evaporation and wind before it soaks in. Evening is the next best option, though damp foliage overnight can encourage fungal disease. Watering in the heat of the day wastes the most.

What is the most water-efficient irrigation for a home garden?

Drip irrigation and sub-surface drip are the most efficient, delivering most of the water directly to the root zone. Soaker hoses are a simple, low-cost alternative for beds. Adding a timer helps avoid overwatering. Sprinklers and hand hosing are generally less efficient, although hand watering can be well targeted if done carefully.

Are there water rebates for gardeners?

Some water utilities, councils and state programs have offered rebates for rainwater tanks, efficient irrigation or soil moisture sensors, but offers change and vary by location. Check your water provider’s and local council’s websites for what is currently available.

Brought to you by Garden Yard Australia, your Australian garden and outdoor living store.
Estimates use typical climate and efficiency figures and will differ from your actual usage and water bill.