When it rains, water slowly builds up in the roof gutter system before it exits through the downpipe.
The first flush of water from the roof can contain amounts of bacteria from decomposed insects, lizards, bird and animal droppings and concentrated tannic acid. It may also contain sediments, water borne heavy metals and chemical residues, all of which are undesirable elements to have in a water storage system.
Instead of flowing to the water tank, these pollutants are diverted with the initial flow of water into the chamber of the water diverter. The water diverters from Rain Harvesting utilize a dependable ball and seat system -
a simple automatic system that does not rely on mechanical parts or manual intervention.
As the water level in the diverter chamber rises the ball floats, and once the chamber is full, the ball rests on a seat inside the diverter chamber preventing any further water entering the diverter. The subsequent flow of water is then automatically directed along the pipe system to the tank.
For a Water Diverter to work effectively,
the contaminated water in the chamber must be sealed off. This prevents the contaminated water from passing to the storage tank and ensures the water does not "siphon" off the contaminated water in the chamber. The simplest and surest way to do this is with a floating ball and seat.
Simple and effective first flush devices, these are installed at the downpipe and used when there are a small number of downpipes supplying water to the tank.
A slow release valve ensures
the chamber empties itself after rain and resets automatically. The diverted water need not be wasted water because the drain pipe from the diverter chamber can be fitted to a standard drip irrigation system.
It is preferable to fit the longest length chamber possible to ensure better quality water. Install the chamber below the gutter filter (or rain head), to within 6" above the ground to allow easy access to the end cap.
Downpipe Diverters should be installed at each downpipe that supplies water to the tank. For systems with multiple downpipes or high volumes of water, a Post/Wall Mounted Diverter or In-Ground Diverter may be more effective.
The diverters are supplied in kit form and come with everything needed to complete installation - just add the length of PVC pipe required to form the diverter chamber.
Water Diverters work best when a gutter downspout filter (sometimes called a rain head) is installed upstream of the diverter. Fitted at the downpipe either directly on the underside of the roof gutter or to a wall, the
Leaf Eater or Leaf Beater rain heads, also from Rain Harvesting, are self cleaning devices that deflect leaves and debris away from the flow of rainwater. Rain heads ensure the diverter chamber and Slow Release Control Valve do not block up as easily. They not only help Water Diverters operate more efficiently in preventing fine sediments and pollutants from entering the rainwater tank, they also ensure Water Diverters drain and reset automatically after rainfall, significantly reducing system maintenance.
Important Winterization Instructions:
Before the first hard freeze, simply remove the bottom "Screw Cap" to prevent the first flush PVC reservoir pipe from collecting water, that upon freezing, can possibly cause fracturing during a hard freeze. The PVC tube should be fully drained in order to prevent damage to the diverter chamber. Store the bottom cap and be sure to screw it back on for warmer weather and fully resume the first flush functionality.
An optional primary upgrade screen is available. The plastic screen provides extra confidence with additional filtration of fine sediments and pollutants to ensure the slow release control valve does not block.
Diversion Recommendations for the Roof
Minimal Pollution: divert 0.0125 gallons per square foot of roof areaOpen field, no trees, no bird droppings, clean environment
Substantial Pollution: divert 0.05 gallons per square foot of roof areaLeaves and debris, bird droppings, various animal matter, e.g. dead insects, lizards, etc.
Example for a minimal polluted roof of 1,000 square feet:1000 square feet X 0.0125 = 12.5 gallons to be diverted
Example for a heavily polluted roof of 1,000 square feet:1000 square feet X 0.05 = 50 gallons to be diverted
PVC Pipe Specifications
3" Downspout diverters: Use 3" Schedule 40 PVCStorage capacity: Each 3 foot section of 3" PVC holds approximately 1.1 gallons of water (0.3840341 gal/ft)
(not sewer and drain pipe)
4" Downspout diverters: Use 4" Schedule 40 PVCStorage capacity: Each 3 foot length of 4" PVC holds approximately 2 gallons of water. (0.661312 gal/ft)
(not sewer and drain pipe)
Post/Wall and In-ground First flush diverters: Use 4" Schedule 40 PVCStorage capacity: See
Delta Diversion Chart on our In Ground First Flush page, for exact calculations
Upgrade your First Flush system to the new
Advanced Release Valve and you'll never have to repair the ball and seat system or replace the rubber disks again!
In freezing climates, all water should be drained from the first flush system and the inlet should be shut off to prevent additional water from entering the system. If preventive maintenance is not performed, damage to the first flush system, including ice crushing the plastic ball, may occur. The Advanced Release Valve eliminates the use of washers and allows for much greater control over the release rate of the first flush chamber.
First Flush Upgrade Filter Video: