How Much Water Could You Be Collecting Off Your Roof
Here’s how to calculate how much water your rainwater tank could collect…
Every 1mm of rain that falls on every square metre of roof equals 1 litre that could be collected in your tank.
So the formula is:
1m x 1m x 1mm = 1 litre
Example:
160m² of roof x 5mm rain = 800 litres
250m² of roof x 15mm rain = 3750 litres
Now you see how much water you can easily collect, cross-refer this information to the tank charts to see what size tank you need. Slimline watertanks Round tanks
Water calculator
Enter roof area (m²)
Rain in mm