A first flush system is designed to capture and divert the initial runoff from rainwater harvesting systems, which may contain debris, contaminants, or pollutants that have accumulated on rooftops or other surfaces. The purpose of this system is to improve the quality of harvested rainwater by discarding the first portion of the runoff and allowing cleaner water to be collected afterwards. Below are the steps to set up a first flush system for water harvesting:
Understand the Concept: Familiarize yourself with how the first flush system works. The basic idea is to use a diverter to redirect the initial flow of water away from the storage tank and into a separate pipe, where it is held until the system is flushed clean. This ensures that the first flush water, which might contain contaminants, doesn't enter the storage tank.
Gather Materials and Tools:
PVC pipe and union
Tank and a valve
T-joint
Elbow joint and cap
Metal saw
Screwdriver
Fine mesh filter to remove larger debris getting in the tank
Install the First Flush System: Follow these steps for installation: a. Attach the downspout diverter or rainwater diverter at the beginning of the rainwater downspout. b. Connect a pipe from the diverter to the first flush chamber, which could be a separate holding tank or a section of pipe. c. Ensure the first flush chamber has an overflow outlet, which allows excess water to bypass the chamber and continue to the storage tank after heavy rainfall. d. Install a flushing mechanism, like a ball valve or just a cap, at the bottom of the first flush pipe. e. Consider adding some filtration media at the entry point of the tank to catch larger debris.
Maintenance: Regularly inspect and maintain the first flush system. Clean the first flush chamber periodically to remove accumulated debris, sediment, or pollutants. Ensure that the flushing mechanism operates smoothly.
By implementing a first flush system, you can improve the quality of harvested rainwater and maximize its potential for various non-potable uses, such as watering plants, flushing toilets, or washing hands.