This is an important question and the figures can get quite involved so to begin let's try and keep it simple...

In essence you need to think about a number of key factors when sizing for rainwater harvesting, otherwise you won’t get the best performance from the system you install.

So it’s really important to get the figures right and strike the correct balance between these elements:

• Rainwater yield.
• Rainwater demand.
• Budget.
• Overflow frequency.
• Future proposed applications.

For more details on how to size a rainwater harvesting system click here.