Rainwater tank calculator for Cairns
Cairns averages about 1,959 mm of rain a year (long-term average at the Bureau of Meteorology’s Cairns Aero station). Every square metre of roof collects roughly 1 litre per millimetre of rain, so a typical Cairns home can harvest a lot of water.
Rain you can collect in a year
| Roof area | Metal roof (×0.9) | Tiled roof (×0.8) | Average per day (metal) |
|---|---|---|---|
| 80 m² | 141,048 L | 125,376 L | 386 L |
| 100 m² | 176,310 L | 156,720 L | 483 L |
| 150 m² | 264,465 L | 235,080 L | 725 L |
| 200 m² | 352,620 L | 313,440 L | 966 L |
| 250 m² | 440,775 L | 391,800 L | 1,208 L |
| 300 m² | 528,930 L | 470,160 L | 1,449 L |
Work it out for your roof
The calculator below is pre-filled with Cairns’s average rainfall. Change the roof area, daily use and tank size to match your home.
Your measurements
Estimates only. Check sizes, coverage and quantities with your supplier, engineer or certifier before ordering. Standards references are a guide, not compliance advice.