- Rain Barrels
- Packaged Systems
Downspout First Flush Water Diverters improve water quality and reduce tank maintenance by preventing the first flush of water, which may contain roof contaminants, from entering the tank. They help ensure cleaner water is available for use, which protects rainwater pumps and internal household appliances such as clothes washing machines, toilets, hot water systems, etc.
The New First Flush Water Diverter ADVANCED allows less "dirty" water to skip over the first flush chamber. The tee incorporates a unique flow direction feature that forces fast-flowing water into the diversion chamber, preventing the water from entering your rainwater tank. With this kit, 4x less "dirty" water bypasses the diversion chamber, and 97% of first flush water is diverted.
This Advanced model improves upon the First Flush Water Diverter Plus by adding an electronic advanced release valve, giving you greater control over how frequently you release your diverted water. Increase your release frequency to maximize water quality or release the dirty water less frequently to maximize stored water volumes.
Supplied in kit form, the First Flush Diverter Advanced can be installed on your downspouts with a simple T junction. Simply add and install the length of pipe required to meet your diversion needs. This will be based on the volume of dirty, contaminated water you wish to divert.
Fitting an appropriately sized First Flush Water Diverter is critical to achieve good quality water. Water Diverters improve water quality, reduce tank maintenance and protect pumps by preventing the first flush of water, which may contain contaminants from the roof, from entering the tank.
When it rains, water slowly builds up in the roof guttering system before it exits through the downspout. The first flush of water from the roof can contain amounts of bacteria from decomposed insects, 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.
It is important to prevent heavy sediments and other roof pollutants from entering the rainwater tank/cistern. The amount of water diverted should be a minimum of 12.5 gallons per 1000 square feet of roof area (or 0.0125 gallons per square foot). In calculating the amount of water to divert, consideration can be given to (1) the surface area of the roof, and (2) the amount of pollutants on the roof and gutters.
The following factors can be used as a guide in determining the volume of water to be diverted.
As a rule of thumb, the more water that is diverted, the better the quality of water in the tank/cistern.
1. Determine the length of Diverter Chamber #4. Consider as a guide
– 3 foot section of 3″ Schedule 40 PVC pipe holds approx. 1.5 gallons
– 3 foot section of 4″ Schedule 40 PVC pipe holds approx. 2 gallons of
Fit the longest length of pipe possible, making sure the Screw Cap
#10 is at least 6″ from the ground to allow for removal and
2. Place the ball Seat #9 into the Tee Junction #6 ensuring the narrow
end of the ball seat points down into the Diverter Chamber #4. Apply
glue to the Diverter Chamber #4 and fit up against the Ball Seat #9
and hold until the glue sets. (Optional: Use a 45º bend adaptor to
allow easier removal of the Screw Cap #10). Glue the Socket #14 to
the bottom end of the Diverter Chamber #4.
3. Fix the assembled chamber directly to the wall in the desired position
using the Wall Brackets.
4. Connect a Male & Female (M&F) Elbow #8b (if required) to the
Chamber Outlet #8 and connect the downspout #3. Fit an elbow to
the InFeed pipe #2 (if required) and connect to the bottom of the
selected rain head.
5. Select the appropriate Flow Control Valve #11 and insert into the
Hose Connector #16, making sure the valve is inserted with the side
marked “TOP” still showing. Start by using the Control Washer with
the smallest gauge hole (lowest number). Try a larger gauge Washer
if experiencing blockages. Place the Filter Screen #13 into position
from the outside of the Screw Cap #10 and then attach the Hose
An extra filter screen that helps stop the Control Valve blocking is
available from your local store. Ask for the “Optional Stainless Steel
Primary Screen” (Product Code: WDAC02). This filter is fitted in
addition to the Plastic Filter Screen #13. To install: After completing
step 5, insert the Keeper Ring #1a into the Screen Cap #10 and then
place the Optional Stainless Steel Primary Screen on top of the Keeper
Ring #1a. Proceed to step 6.
6. Place the Sealing Ball #5 into the Diverter Chamber #4 and attach the
assembled Screw Cap #10 to the Socket #14.