Commercial First Flush Diverter | Rain Harvesting by Blue Mountain Co

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Kit
150mm
225mm

First Flush Commercial

First Flush Diverters
Divert large volumes of the dirtiest water that washes off your building’s roof to protect your rainwater quality.
Size 150mm WDDP03
Size 225mm WDCL30
  • 150mm
  • 225mm

THIS IS A DISCONTINUED VERSION OF THE RAIN HARVESTING COMMERCIAL FIRST FLUSH AND IS NO LONGER AVAILABLE.
BLUE MOUNTAIN CO ALWAYS WORKS TO BETTER OUR CUSTOMER SERVICE AND PRODUCTS AND AS PART OF THIS PHILOSOPHY WE HAVE INTRODUCED A NEW AND IMPROVE COMMERCIAL FIRST FLUSH IN 2019.
IF YOU HAVE ANY QUESTIONS ABOUT THE PREVIOUS COMMERCIAL FIRST FLUSH, PLEASE REFER TO THE INFORMATION ON THIS PAGE OR USE OUR CONTACT US PAGE TO GET IN TOUCH.

Commercial FF Tee

Divert more water

The First Flush Commercial’s size allows it to divert significantly larger volumes of the most contaminated water that washes off your roof. This makes it suitable for schools, hotels, warehouses and other sizeable commercial and non-commercial buildings. (Note: 225mm tee pictured)

Commercial FF Filter

Keep contaminants out of your tank

By keeping the dirtiest water out of your tank, this first flush diverter provides significant protection to your rainwater quality. This water is often laden with hazardous contaminants such as bacteria, organic fine particles, heavy metals and other pollutants – so it pays to keep it out. (Note: 225mm end cap pictured)

 

Commercial First Flush Perspective

Install with ease

The First Flush Commercial comes in an all-inclusive kit, including a stand (225mm). Simply add glue and a length of pipe that’s suitable for containing your desired diversion volume. Key components can be removed where necessary for easier maintenance. (Note: 225mm product pictured)

Calculate your diversion needs 

Generally speaking, the more water you divert, the better the quality of the rainwater that ends up in your tank. However, diverting more rainwater than necessary can lead to volume shortages, so it’s important to calculate your diversion needs, and divert water accordingly.  

The following formulas offer general guidelines for calculating how much water you should divert: 

  • Areas with low pollution (open fields, no trees, no bird droppings or animal matter, clean environment) = divert 0.5 litres of water per square metre of roof 
  • Areas with higher pollution (leaves and debris, bird droppings, animal matter/carcasses, pollution) = divert at 2 litres of water per square metre of roof.  

This calculation will allow you to determine what length and size pipe or pipes you need for your diversion chambers.

The length of pipe required to form your first flush diversion chamber will depend upon how much water you need to isolate and capture. The following measurements are given as a guide only.

1 metre of 90mm pipe = 5.7 litres
1 metre of 150mm pipe = 18.8 litres
1 metre of 300mm pipe = 72 litres
3 feet of 4″ pipe = 2 gallons
1 metre of 100mm pipe = 8.8 litres
1 metre of 225mm pipe = 45 litres
3 feet of 3″ pipe = 1.5 gallons
3 feet of 12″ pipe =19 gallons

Benefits of First Flush Water Diverters

First Flush diverters help you plan for volume by allowing you to choose your catchment volume with custom catchment size and/ or an advanced release valve.

First Flush Diverters help divert the first flush, through their design. They are installed using a T junction or high flow inlet to which the diversion chamber is fitted. As the chamber fills with the initial dirty water from your roof, a ball rises until it seals the inlet, allowing the rest of your rainwater, which is much cleaner, to flow directly to your tank.

Learn more about the 4 pillars of designing a Rain Harvesting system. 

The Rain Harvesting steps addressed:

Limit sources of contamination     Plan for volume

Filter leaves and debris                    Divert the first flush

Secure the system                             Manage standing water

Consider a safety net                        Monitor and maintain

  • Specifications

  • Installation
    1. Determine the length of 225mm pipe required for your first flush diversion chamber using the table below and cut accordingly. Ensure all cut edges are clean and smooth.
    2. Attach the lower end cap to your 225mm pipe using solvent weld cement.
    3. Push the flap valve up inside your T-junction socket with the flap facing down. Solvent weld glue the T-junction to the top of your 225mm pipe to secure the flap valve in place.
    4. Fit your first flush unit into the stand and solvent weld the T-junction to the main pipework.
    5. Select one of the flow control washers and fit it into the hose connector, with the side marked “TOP” showing. Save the remaining washers for possible future use.
    6. Insert the plastic filter screen in through the base of the screw cap with O-ring seal and secure by attaching the hose connector and flow control washer.
    7. Place the stainless steel filter and 8mm (0.3″) keeper ring through the lower end cap outlet, then screw the screw cap with O-ring seal (and assembled components) to the lower end cap outlet.
    8. Securely bolt the stand and check to ensure that the pipework connected to the top of your First Flush Commercial is stable and the unit is not stressed by bad alignment.
    9. Remove the bottom screw cap and insert the 20 balls inside your first flush diversion chamber, then replace the screw cap.

     

    Diversion chamber volume (litres) Total length of 225mm pipe required (metres)
    20 .40
    30 .70
    40 .90
    50 1.10
    60 1.30
    70 1.50
    80 1.80
    90 2.00
    100 2.20
    120 2.60
    150 3.30
  • Maintenance

    It’s important to ensure that your first flush diverter outlet remains clear of any debris. If your outlet becomes blocked, the chamber will not empty and the first flush of water will not be diverted when it rains.

    To ensure the flow of water out through your diverter’s outlet, periodically unscrew the outlet to allow debris to fall out. If the diversion chamber is full of water, take care as it empties. Remove the flow control washer, hose connector, keeper ring and filter screens and hose or wash the screens with clean water. Check the flow control washer for any blockages and remove and clean as necessary.

    For best results and minimal maintenance, we recommend installing rain heads such as our Leaf Eater rain heads on all your downpipes to limit the volume and number of leaves and debris that reach your first flush diverter.

  • What's in the box?
    • stand
    • end caps (1 with screw fitting)
    • hose connecter
    • 8 flow control washers
    • plastic filter screen
    • screw cap with O-ring seal
    • threaded coupling
    • First Flush primary filter screen
    • 90mm/3″ keeper ring (8mm/0.3″)
    • 20 balls
    • flap washer
    • T-junction
  • Tools you might need
    • 225mm pipe (for diversion chamber)
    • Tape measure
    • Marker pen
    • Saw
    • Glue or sealant
  • Product FAQs

    What comes in my first flush diverter kit?

    The exact components included in your first flush diverter kit will depend upon the product you order and are listed on each individual product page. (For product-specific information, visit the product page for your chosen first flush diverter via the links above.) 

    Where should I install my first flush diverter?

    Your first flush diverter can be installed anywhere between your roof catchment area and your rainwater tank to isolate and capture the first “flush” of dirty water at the beginning of a rain event. You may choose to install smaller diverters to divert rainwater from each downpipe or you may choose to install larger diverters to divert rainwater from several downpipes. 

    How much water should I divert?

    In areas with mild pollution (e.g. open fields, no trees, no bird droppings or animal matter, clean environment) you should divert 0.5 litres per square metre of roof (0.0125 gallons per square foot of roof). In areas with higher pollution (e.g. leaves and debris, bird droppings, animal matter/carcases, pollution) you should divert 2 litres per square metre of roof (0.05 gallons per square foot of roof). These formulas will help you calculate your total diversion volume or, if you’re using more than one first flush diverter, the volume of water you should divert in each device (which will depend upon the size of the roof area that “feeds” each diverter). 

    How long should my first flush diversion chamber be?

    The length of pipe required to form your first flush diversion chamber will depend upon how much water you need to isolate and capture. The following measurements are given as a guide only. For product-specific information, visit the support page for your first flush diverter.  

    1 metre of 90mm pipe = 5.7 litres 

    1 metre of 100mm pipe = 8.8 litres 

    1 metre of 150mm pipe = 18.8 litres 

    1 metre of 225mm pipe = 45 litres 

    1 metre of 300mm pipe = 72 litres 

    3 feet of 3″ pipe = 1.5 gallons  

    3 feet of 4″ pipe = 2 gallons 

    3 feet of 12″ pipe =19 gallons 

    Can I run two or more pipes into one first flush diversion chamber?

    Yes. Just remember that you need to size your first flush diversion chamber based on the size of the roof area that’s upstream from your diverter. If two or more pipes (aka lines) feed into a single diverter, you should size your diversion chamber accordingly by considering the total roof area that feeds both pipes. 

    Which flow control washer (valve) should I use?

    Your first flush diverter comes with a range of flow control washers (valves). Each washer has a different sized hole. The size of the hole determines the rate at which your first flush diversion chamber will empty. A smaller hole will create a slower flow rate and release less water during a rain event, while a bigger hole will create a higher flow rate and release more water during a rain event. (Blockages excepted, any size washer will eventually fully empty your diversion chamber after each rain event.) Washers with a smaller hole will become blocked sooner than washers with a larger hole. Choosing your flow control washer is therefore a trade-off – lower wasted water during rainfall means more regular maintenance, while moderate wasted water during rainfall means less maintenance is required. However, when choosing your flow control washer, remember that the volume of water flowing from the largest washer, which has a 2mm diameter hole, will still be insignificant when compared to the rainfall flow rate. 

    Which way should the ball seat be oriented?

    Your diverter’s ball seat is like a funnel: \  /. The narrow end is installed facing down so it can be sealed by the black ball. (For detailed installation instructions, visit the Support page for your chosen first flush diverter.) 

    How do I plumb the trickle feed outlet on my first flush diverter?

    You can use 12mm irrigation tubing to plumb the trickle feed outlet to a location away from the diverter. 

    How do I clean my first flush diverter?

    Slowly unscrew the black hose fitting from the bottom of your first flush diverter. If the diversion chamber is full of water, take care as the water empties. Remove the plastic filter (it may come out when you remove the black hose fitting) and wash under clean water. Check the flow control washer for any blockages and wash with clean water, then replace all these parts. (For product-specific maintenance instructions, visit the Support page for your chosen first flush diverter.)

Products you may be interested in

Leaf Eater Commercial (Metal)
Leaf Eater Commercial (Metal)
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Maelstrom Filter
Maelstrom Filter
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Vent Cowl Weatherproof
Vent Cowl Weatherproof
50mm or 100mm

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