Rainwater Harvesting for the Garden

Why Harvest Rainwater

Even in Australia's variable climate, a well-designed rainwater system can supply a significant proportion of garden water needs, reducing bills and insulating your garden from water restrictions.

Tank Sizing

The rule of thumb is 1,000L of storage per 30m² of roof catchment area. A 200m² roof can fill a 5,000L tank from a single 25mm rainfall event. For most suburban homes, 2,000–5,000L provides useful buffering.

First-Flush Diverters

The first flush of rain after a dry period washes bird droppings, dust, and debris off the roof. A first-flush diverter automatically discards the first 20–25L before allowing cleaner water into the tank. Essential for vegetable garden irrigation.

Distribution

A tank raised 50–70cm above ground level provides enough gravity head for drip irrigation. For overhead sprinklers or spray, a small submersible pump ($80–150) provides adequate pressure.