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Rainwater Harvesting Formula:
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The rainwater tank sizing formula calculates the optimal water tank volume based on roof catchment area and local rainfall data. This helps determine the appropriate tank size for rainwater harvesting systems in New Zealand.
The calculator uses the rainwater harvesting formula:
Where:
Explanation: The formula accounts for the relationship between catchment area, rainfall volume, and system efficiency to determine optimal tank capacity.
Details: Proper tank sizing is crucial for maximizing water collection efficiency, ensuring adequate water supply during dry periods, and optimizing investment in rainwater harvesting systems.
Tips: Enter roof area in square meters and average rainfall in millimeters. Use local rainfall data for accurate results. All values must be positive numbers.
Q1: Why is there a 0.8 efficiency factor?
A: The 0.8 factor accounts for system losses including evaporation, first flush diversion, and overflow during heavy rainfall events.
Q2: What rainfall data should I use?
A: Use average monthly or annual rainfall data for your specific region in New Zealand for the most accurate results.
Q3: How do I measure roof area?
A: Calculate the horizontal projection area of your roof. For complex roof shapes, break it down into simple geometric shapes and sum the areas.
Q4: Should I consider water usage patterns?
A: Yes, for optimal system design, also consider your household water consumption patterns and the length of dry periods in your region.
Q5: Are there regional variations in New Zealand?
A: Yes, rainfall patterns vary significantly across New Zealand, so it's important to use location-specific rainfall data for accurate calculations.