Quick Answer
A first flush diverter system is a crucial component of a rainwater harvesting system, designed to separate the first flow of water from a roof, which may be contaminated with debris, dirt, and pollutants, from the rest of the water. This system ensures that clean water is collected and stored for use. The system is typically installed at the point where the downspout meets the collection tank.
Understanding First Flush Diverter Systems
A first flush diverter system consists of a few key components: a diverter valve, a float or sensor, and a overflow or bypass pipe. The diverter valve is the heart of the system, directing the flow of water between the overflow pipe and the collection tank. The float or sensor is typically placed in the overflow pipe and activates the diverter valve when it reaches a certain water level. This causes the valve to switch, allowing the first flush of contaminated water to flow out of the overflow pipe while the clean water flows into the collection tank.
Components and Installation
The diverter valve can be manual or automatic, with the former requiring periodic maintenance to ensure proper function. Automatic valves are generally more reliable, but may be more expensive. The overflow or bypass pipe should be sized to handle the first flush of water, typically the first 10-15 gallons of water that flow from the roof. This can be calculated based on the roof’s surface area and the anticipated rainfall intensity. When installing a first flush diverter system, it’s essential to ensure that the entire system is sloped to allow for proper flow and prevent back-siphoning. A minimum slope of 1/4 inch per foot is recommended.
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