Rainwater Harvesting Tank Size Calculator

What size rainwater tank do I need?

Use the quick form below to see the ideal tank size for your requirements..

Step 1: Personal Information

Step 2: Roof Size

Insert the collection area in square metres (NB. This is the roof area only and not surface/driveways etc.) As a guide, you can measure the surface area of your overall floor plan for your house. (W x D = roof size)

Tip: The average UK roof size is 100 m2 (1076 ft2).

m2 ft.2

Step 3: Rainfall

Please enter your postcode so that we can estimate the rainfall for your area.

Estimated Rainfall  mm

Step 4: Number of people

Please select the number of people living in your household.

Tip: It’s important to size the RWH system to the property and not just the number of people living in it at this time.

Step 5: Rainwater Use

What will you use your collected rainwater for?