Usage & Capacity

Usage & Capacity

How can I calculate how much water I currently use?

Use the following table as a guide to calculating your average weekly water consumption. For example, an average 2 person household with garden would use approx 4,760L of water per week.

Household Occupancy Bathroom Laundry Kitchen Garden Subtotal (per day) Total (per week)
1 person 250L per day 120L per day 35L per day 135L per day 540L 3,780L
2 people 360L per day 130L per day 40L per day 150L per day 680L 4,760L
4 people 650L per day 150L per day 45L per day 165L per day 1,010L 7,070L



How much rain will it take to fill the tank?

This is a simple calculation. 1mm of rain on every square metre of surface area results in 1 litre of water into the tank.

Let's say that your house roof is 12 metres long by 10 metres wide. 12m x 10m = 120m2. If you had a very brief storm that dropped 1mm of rain on the roof, you would receive 1mm x 120m2 = 120 litres of rainfall into the tank. A larger storm comes through and drops 25mm of rain: 25mm (rainfall) x 120m2 (roof area) = 3,000 litres of rainwater into your tank.

This calculation works for any roof area; all you need to know to calculate your roof surface area is:

length (in metres) x width (in metres) = surface area (in square metres)