Quick Answer
Store collected rainwater in a clean, covered tank with a maximum capacity to hold at least 12 hours of roof runoff to account for potential spills. Regularly inspect and clean the tank, and use a first flush device to divert debris and contaminants from the roof. Monitor water quality and treatment options.
Tank Sizing and Selection
When choosing a tank for storing collected rainwater, consider the roof catchment area, desired storage capacity, and local building codes. A general rule of thumb is to provide at least 12 hours of roof runoff capacity to account for potential spills. For example, a 1,000 square foot roof will require a 1,200-1,500 gallon tank to hold 12 hours of runoff. Select a tank made from durable, food-grade materials like HDPE or stainless steel.
First Flush Devices and Pre-Treatment
Install a first flush device at the roof’s downspout to divert debris and contaminants from the roof during the initial flow of water. This device typically consists of a diverter valve that opens to allow the first 10-20 gallons of water to flow away from the tank, followed by the clean water. Consider adding a pre-treatment system, such as a sediment filter or skimmer, to the tank’s inlet to further remove debris and contaminants.
Water Quality Monitoring and Treatment
Regularly inspect and test the stored rainwater for pH, turbidity, and bacterial contamination. Consider adding a treatment system, such as a UV filter or membrane bioreactor, to the tank’s outlet to ensure safe drinking water quality. Monitor the tank’s water level, inspect the tank’s condition, and perform regular maintenance to prevent contamination and maintain water quality.
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