1. What is the Rainfall to Water Volume Calculation?

This calculation converts rainfall depth over a given area into total water volume. It's useful for rainwater harvesting, irrigation planning, and stormwater management.

2. How Does the Calculator Work?

The calculator uses the equation:

Where:

• \( rainfall\_in \) — Rainfall depth in inches
• \( area\_sqft \) — Area in square feet
• 0.623 — Conversion factor (gallons per square foot per inch of rain)

Explanation: One inch of rain falling on one square foot of area yields approximately 0.623 gallons of water.

3. Importance of Water Volume Calculation

Details: Knowing water volume from rainfall helps in designing rainwater collection systems, calculating irrigation needs, and managing stormwater runoff.

4. Using the Calculator

Tips: Enter area in square feet and rainfall depth in inches. Default rainfall is 1 inch. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Why 0.623 as the conversion factor?
A: It comes from 1 cubic foot = 7.48052 gallons, and 1 inch = 1/12 foot, so 7.48052/12 ≈ 0.623 gallons per square foot per inch.

Q2: How accurate is this calculation?
A: It's theoretically precise, but actual collection may be less due to evaporation, absorption, and system inefficiencies.

Q3: Can I calculate for multiple inches of rain?
A: Yes, simply enter the total rainfall depth in inches (e.g., 2.5 for two and a half inches).

Q4: What about metric units?
A: For metric: 1 mm rain on 1 m² = 1 liter. Conversion factor is 1.

Q5: How much water is that for a typical roof?
A: A 1,000 sq ft roof collects about 623 gallons per inch of rain - enough for substantial irrigation or non-potable uses.