Quick Answer
A first flush diverter typically captures between 10 to 30 gallons of water, depending on the system size and design. This amount includes the initial flow that goes directly into the storage tank. Proper installation and maintenance ensure the captured water quality.
Understanding First Flush Diverter Capacity
A first flush diverter’s capacity is determined by its size, slope, and the roof’s surface area. A common size for a residential system is a 1:12 slope, which allows for a 10-gallon capacity. Larger systems, such as those for commercial buildings, can range from 20 to 50 gallons.
Calculating System Capacity
To determine the required system capacity, consider the roof’s surface area, rainfall intensity, and desired storage volume. A general rule of thumb is to calculate the roof’s surface area in square feet, multiply it by 0.5 inches of rainfall per hour, and then divide the result by 7.48 gallons per square foot. This will provide the system’s required storage volume in gallons.
Practical Considerations for System Size
When selecting a first flush diverter, consider the installation location, pipe size, and material. Ensure the system’s components are compatible and can handle the required flow rate. For example, a 1-inch pipe can handle up to 2.8 gallons per minute, while a 1.5-inch pipe can handle up to 4.2 gallons per minute. Proper sizing and installation are crucial for efficient water capture and storage.
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