First Flush Carrot | Rain Harvesting by BMCo
New
Kit
90mm
100mm

First Flush Carrot

First Flush Diverters
Divert your initial roof runoff without the need for a traditional First Flush storage chamber and ensure only the cleanest water reaches your tank.

The First Flush Carrot uses a clever mechanism to measure and discard the first flush of water, and then seals off to send the best water to your tank.

The compact design allows the unit to be installed in tight spots and is supplied in an all inclusive kit.
Size 90mm WDDP30
Size 100mm WDDP31
  • 90mm
  • 100mm
Ff Carrot 90mm Insitu

The most compact First Flush Diverter

The Carrot’s innovative design makes it the most compact first flush solution for your rain harvesting system, with the ability to fit almost anywhere. While it is a compact unit, The Carrot still allows for the full benefit of flushing away the crucial first portion of rainfall and dirty water from your roof.

Carrot Ksp Inside

Effective First Flush Diversion

The First Flush Carrot automatically measures and diverts the first flush of rainfall from your roof without requiring a traditional storage chamber. This first wash of the roof contains the most contaminants, meaning that you will end up with the best quality water in your rainwater tank.

Carrot Ksp Grommet

Easily adjusted for your needs

The First Flush Carrot comes pre-configured to divert around 20L (5 gal), but can be adjusted with easily switched washers so that you can maximise your water catchment and optimise the quality of water you collect. Diverting more water gives you better quality, diverting less means that you capture more rainwater. The Carrot gives you the power to choose.

How it works

The First Flush Carrot uses a special mechanism which automatically measures and discards the first portion of rainfall which falls on your roof.

It will discard about the first 20 litres (5gal) of rainfall which will include the most pollutants from your roof. Then the Carrot will activate, sending the remainder of the rain water straight to your tank. This means you capture the best quality rain water.

Product Overview:

Adjusting Water/Grommets

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. 

Installation

Cleaning and Maintenance

  • Reference Chart

  • Specifications

     

  • What's in the box?
    • First Flush Plus tee
    • Carrot housing
    • Carrot Upper Collar with O-Ring
    • Carrot Lower Slip Coupling
    • Pipe wall brackets x 2
    • Filling grommets (A & B)
    • Draining grommets (0, 1, 2 & 3)
    • Draining wick with grommet
    • Wick blanking grommet
    • Carrot spring
    • Carrot seal
    • Carrot flow diffuser
    • Carrot
    • Carrot filler frame
  • Tools/materials you may require
    • Tape measure
    • Marker pen
    • Saw
    • Solvent weld glue
    • Screws
    • Drill or screwdriver
  • Installation

    First Flush Carrot 90mm

    1. Your carrot will come pre assembled out of the box with Filling grommet A installed on the Carrot Filler Frame, and Draining grommet 2 installed on the Carrot. The Wick blanking grommet will be installed as standard. This default setup is a good starting off point to reliably divert an average amount of water with a longer reset time.

    2. Determine the installation location for your Carrot First Flush Diverter. The First Flush Plus tee can be installed in the horizontal or vertical orientation to suit your installation (see Figure 1). Note however that the Carrot Diverter Chamber itself must be installed in a vertical orientation.

    3. Select the orientation of the First Flush Plus tee appropriate for your chosen installation point. This will determine which socket on the First Flush Plus tee will attach to your Carrot Diverter Chamber.

      Example: If you’re installing your First Flush Carrot into a horizontal pipe, the arrow marking the direction of water flow should be oriented in the direction of flow (see Figure 1b). For installations using the tee in vertical positions, always ensure the arrow is pointed ‘up’ (see Figure 1a).

    First Flush Carrot 100mm

    1. Your carrot will come pre assembled out of the box with Filling grommet A installed on the Carrot Filler Frame, and Draining grommet 2 installed on the Carrot. The Wick blanking grommet will be installed as standard. This default setup is a good starting off point to reliably divert an average amount of water with a longer reset time.

    2. Determine the installation location for your Carrot First Flush Diverter. The First Flush Plus tee can be installed in the horizontal or vertical orientation to suit your installation. Note however that the Carrot Diverter Chamber itself must be installed in a vertical orientation.

    3. Select the orientation of the First Flush Plus tee appropriate for your chosen installation point. This will determine which socket on the First Flush Plus tee will attach to your Carrot.

      Example: If you’re installing your First Flush Carrot into a horizontal pipe, the arrow marking the direction of water flow should be oriented in the direction of flow (see Figure 1b). For installations using the tee in vertical positions, always ensure the arrow is pointed ‘up’ (see Figure 1a).

    4. Measure your existing downpipe and cut to create space for the First Flush Plus tee. Ensure all cut edges are clean and smooth. Install your First Flush Plus tee in place by applying solvent weld glue to the incoming and outgoing sockets and pipe. Leave the lower socket for now. Insert the pipe into the incoming and outgoing sockets at either end of the First Flush Plus tee.

    5. Apply solvent weld glue to the Carrot Upper Collar and the lower socket of your First Flush Plus Tee and insert it firmly in place.

    6. Make sure the o-ring is located in the groove on the underside of the Upper Collar and screw the Carrot housing into position.

    7. Slide the Carrot Lower Slip Coupling onto the outlet of the Carrot housing and install the remaining pipework as required. Note that the First Flush Carrot will divert the first flush of water down this pipe, so routing this pipework to stormwater or another suitable location is necessary.

    8. Attach to the wall using the supplied brackets, supporting the unit until it is fully secured. The upper bracket should sit directly under the First Flush Plus tee where it will hold the weight of the unit.

    9. We recommend that for the first rainfall event you keep the default Filling and Draining grommets installed (Filling grommet A and Draining grommet 2). Once you have assessed the performance of the Carrot in your rainwater harvesting system, adjust the grommets to suit. Refer to the table in this guide for more information.

  • Flushing Guidelines

    Should I choose the Wicking grommet?

    If you have very low rainfall intensities, the wicking grommet will provide the longest reset time, ensuring that you capture the most water possible. It will require more maintenance than the draining grommets (which is simple by just washing the wick out occasionally).

    Examples:

    • You would use filling grommet B with Draining wick with Draining grommet 0 for very low rainfall intensity where you want to capture as much water as possible
    • You would use filling grommet A with Draining grommet 3 for high rainfall intensity on a roof that has high pollution. However this setup would be less suitable for low intensity rainfall as the Carrot may continue to flush water for the entire rain event

    NOTE: Some combinations of filling grommet and draining grommet are less compatible with typical rainfall events than others.

  • Maintenance

    It is important to periodically unscrew the Carrot housing and check the unit is functioning properly. Check that both the Filling Grommet and Draining Grommet have not become blocked. Also check that the spring is functioning correctly and all the internal seals are seated properly.

    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.

Products you may be interested in

New
Kit
First Flush Plus with Max Chamber Upgrade Kit
First Flush Plus with Max Chamber Upgrade Kit
90mm
New
Downpipe Diverter (Inline) Round
Downpipe Diverter (Inline) Round
90mm
New
Advanced Release Valve
Advanced Release Valve
Universal size
Close

Your selection

Add Rain Harvesting or Plumbing products to your list.