Roof catchment planning

Rainwater Harvesting Capacity Calculator

Estimate harvestable rainwater from roof area, rainfall and collection efficiency, then compare storage and monthly demand.

Enter your values

Example values demonstrate the method; they are not product recommendations.

Your result

Enter measured or nameplate values to calculate.

Method

One millimetre of rain over one square metre equals one litre before losses. Harvest = roof area × rainfall × entered collection efficiency.

Important limits

Period totals do not model storm timing, first flush, water quality, treatment, plumbing, local rules or dry-season reliability. Use monthly or daily data for storage design.

Technical reference

Estimate collectable rainwater and storage coverage from roof area, rainfall, collection efficiency and daily demand.

Estimate rainwater collection capacity with Vukar Automation's harvesting tool. Start with the roof area and rainfall inputs.

What to enter

Use current, project-specific values for roof area, rainfall, collection efficiency and daily demand. Check every unit before calculating and compare like-for-like inputs.

How to use the result

Treat collectable rainwater and storage coverage as estimates. Actual collection varies with rainfall timing, roof condition, losses, overflow, maintenance and demand.

Before making a decision

Verify source measurements, equipment specifications and operating conditions. Have a qualified professional review the final selection, safety and installation requirements before purchase, connection or construction.