1. What is Rainwater Harvesting Calculation?

Rainwater harvesting calculation estimates the volume of rainwater that can be collected from a roof surface based on area, rainfall amount, and runoff coefficient. It helps in designing efficient water collection systems for residential and commercial use.

2. How Does the Calculator Work?

The calculator uses the rainwater harvesting formula:

Where:

• \( Area \) — Roof surface area in square meters (m²)
• \( Rainfall \) — Rainfall amount in millimeters (mm)
• \( Runoff\ Coefficient \) — Dimensionless factor (0-1) representing efficiency

Explanation: The equation calculates the potential rainwater collection volume by multiplying the roof area by rainfall amount and adjusting for collection efficiency through the runoff coefficient.

3. Importance of Rainwater Harvesting

Details: Rainwater harvesting is crucial for water conservation, reducing dependency on municipal water supplies, and sustainable water management. It provides an alternative water source for irrigation, flushing, and other non-potable uses.

4. Using the Calculator

Tips: Enter roof area in square meters, rainfall in millimeters, and runoff coefficient (typically 0.8-0.95 for clean roofs). All values must be valid positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical runoff coefficient for roofs?
A: For clean, smooth roofs (metal, tile), coefficient is typically 0.8-0.95. For rough surfaces or dirty roofs, it may be lower (0.6-0.8).

Q2: Why convert mm to liters?
A: 1 mm rainfall on 1 m² area equals 1 liter of water, making the conversion straightforward for metric measurements.

Q3: How accurate is this calculation?
A: It provides a good estimate but actual collection may vary due to evaporation, spillage, and first-flush diversion systems.

Q4: Can I use this for large-scale systems?
A: Yes, the formula scales for any size roof area, making it suitable for both residential and commercial rainwater harvesting systems.

Q5: What factors affect runoff coefficient?
A: Roof material, slope, surface condition, and rainfall intensity all influence the runoff coefficient value.