Rainwater Harvesting Yield and Storage Calculator

Estimate collected rainfall and storage autonomy with visible losses.

Harvested water per rainfall event
476.59 US gallons
Inputs
sq ft
Horizontal roof projection area.
inches
Rain depth for one event.
%
Fraction of rainfall reaching the collection system.
%
Downpipe, first-flush, and conveyance efficiency allowance.
US gallons / day
Target daily use.
days
Desired storage autonomy.
Results & Graph
Harvested water per rainfall event
476.59 US gallons

Harvested water per rainfall event

Graph 1 • Calculator-specific flow Shows the calculated components and current result from this tool.
Harvested water per rainfall eventEvent yield476.6Target storage350Roof area1.0kHarvested water per rainfall event: 476.59 US gallons
Graph 2 • Modeled quantities Compares the values returned by the active calculation.
Event yield 476.6 Target storage 350 Roof area 1.0k
Graph 3 • Calculation checkpoints Displays the engine’s named calculation points in order.
0gallons 540gallons 1.1kgallons Event yield: 476.595 gallons 476.6 Event yield Target storage: 350 gallons 350 Target storage Roof area: 1,000 gallons 1.0k Roof area
Summary: The entered roof and rainfall yield 477 gallons; 350 gallons covers the entered use for the target days.
Summary: The entered roof and rainfall yield 477 gallons; 350 gallons covers the entered use for the target days.
⚠️ Assumes inches of rainfall, square feet of roof, and US gallons. Does not account for first-flush loss, overflow, local rainfall distribution, or water quality.

Formula & Mathematical Methodology: Rainwater Harvesting Yield and Storage Calculator

US gallons = roof area × rainfall × 0.623 × runoff fraction × collection efficiency.
US gallons = roof area × rainfall × 0.623 × runoff fraction × collection efficiency.
  • Inputs: All units, rates, and allowances are entered by the user.

Rounding: Displayed values are rounded for readability; package and item quantities round upward.

Worked Example: 1,000 sq ft roof and one inch of rain

Use the default values to review the rainwater harvesting estimate.

  1. Enter measured quantities and current user-supplied rates.
  2. Review the formula and assumptions below the result.
  3. Use the visualization to check the modeled input and output relationship.
Result: Estimate collected rainfall and storage autonomy with visible losses.

Frequently Asked Questions

Are prices or rates updated automatically?

No. Enter the current rate from your provider, supplier, or utility. The tool does not claim live pricing.

Does this convert currencies?

No. A currency selector changes the display denomination only; it does not exchange values.

Construction & Home • Water & Outdoors Guide

How to Use the Rainwater Harvesting Yield and Storage Calculator: Practical Guide & Visual Analysis

Estimate event yield from roof area and rainfall, then compare it with a user-selected storage target. Enter your own measurements, rates, and assumptions; the calculator runs locally in your browser. Whether you are researching rainwater collection calculator, rain barrel calculator, rainwater tank size, rainwater harvesting estimate, rainwater harvesting yield and storage calculator, this interactive tool helps you estimate event yield from roof area and rainfall, then compare it with a user-selected storage target.

Interpreting the 3 Custom Visual Graphs & Key Outputs

As you adjust Roof Catchment, Rainfall Event, Runoff Coefficient, Collection Efficiency, the calculator immediately computes Primary estimate, Input contribution breakdown, Sensitivity visualization and updates all three domain-specific SVG charts in real time. Instead of relying on a single static figure, you can inspect the primary domain diagram, component breakdown, and multi-point trajectory curve to see how changing your inputs shifts the final result. Use the Compare (up to 3 scenarios) button to evaluate side-by-side variations before making a decision.

Real-World Benchmark & Planning Tips (Global screening estimate; verify local units, product data, rates, and rules.)

In our benchmark scenario (1,000 sq ft roof and one inch of rain), Estimate collected rainfall and storage autonomy with visible losses. Keep in mind that entered values remain constant for the modeled interval. For related calculations in Construction & Home, explore Concrete & Square Footage Calculator, Roofing, Stair Stringer, Tile, Mulch/Gravel & HVAC BTU Calculator, Drywall Sheets, Paint Gallons, Siding Squares & Wallpaper Calculator.