Gutter Guard SA 

(DRP Universal Pty Ltd)

First Flush Diverter's for rainwater tanks:

(all prices exclude VAT)

Options and pricing are listed below as well as an explanation of how the system works: (example installation pictures shown further down the page).

  • First Flush DIY Kit (for standard 80mm down pipes) - R295 (supplied in a box with diagram).

First Flush DIY kit includes –

  • Top intake adapter 80 to 110 mm (Intake to fit standard 80mm round downpipes), Float ball, 110mm bracket for mounting the unit to the wall, 80mm round T piece, bottom base cap with screw off lid for cleaning, valve for draining the system.

    You will need:

    -         Drilling machine for mounting the bracket to the wall, 

    -         PVC glue (available from your hardware store or plumbing supplier),

    -         Standard round 110mm diameter plumbing pipe, cut to a suitable length for your specific installation (the 110mm plumbing PVC pipe is sometimes only sold in 4 or 6 metre lengths although some hardware stores or plumbing suppliers will cut a piece for you). Explanation below explaining how to work out what length pipe is required for your specific requirements. 

    -         Additional 80 mm PVC plumbing pipe to connect the T Piece to the tank/First Flush device depending on your set up requirements.

(*Ask for full information sheet and assembly/installation instructions to be emailed to you).

*DIY first flush Kits for 110 mm down pipes also available for R395 ea.

Leaf catcher box if required is sold separately (R250). 

If you prefer a unit already assembled and ready to install: 

·       8 Litre ready assembled system - 950 mm long, standard 110 mm diameter pipe with intake for 80mm round down pipes: holds approximately 8 litres of water: R450 each. (does not include T piece or mounting bracket, sold separately).  

·         4 litre ready assembled system - 450 mm long and 110 mm diameter pipe with inlet for 80mm round down pipes: holds approximately 4 litres water: R390 each.  (does not include T piece or mounting bracket, sold separately).

What are First Flush Systems and how they work:

The “First Flush” rainwater filter system will divert any small or dissolved pollutants from your roof and gutters into a separate pipe so it does not enter the tank.

When it first starts to rain, water slowly builds up in the roof gutter system before it exits through the down pipe. 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.

Gutter mesh and baskets (leaf catchers) will help with leaves and larger debris but can’t stop small bits like dust and bacteria. That is why it is recommended that you install a First Flush Filter. We all know that prevention is better than cure and so it makes sense to stop the pollutants from entering your tank.

How it works:

The first flush device is installed along the gutter down pipe that will feed into your water tank. As the water level in the first flush diverter chamber (110mm pipe) rises, the ball floats and rises. 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 clean water is then automatically directed along the pipe system through the T piece into the rain water tank.

It is best to have one first flush diverter on each downpipe however a single unit can be placed close to the tank and perform a first flush for several downpipes. This will really depend on how big your roof catchment is and how clean you need the water to be.

The amount of water you need to first flush will depend on a few things like:

-          The size of your roof- The recommended minimum first flush is 4L per 20m of roof catchment area.

-          The amount of leaves and pollution on the roof (polluted areas need to be flushed more.

-          The intended use of the water (drinking water will need a bigger first flush).

(You should always check the quality of the water in your tanks before drinking it).

The amount of water flushed is determined by the length of the 110mm PVC (flush) pipe attached to the first flush kit. The average is 1m of 110mm PVC pipe will flush 50sqm of roof catchment area. The 110mm pipe is not included in the DIY kit but is readily available at any good hardware store. (It is sometimes only sold in 4 or 6 metre lengths although some hardware stores or plumbing supplier will cut a piece for you). As an example, 850 mm of 110mm pipe will give you an 8 litre system.

The first flush system is a simple and effective device. After the rain, just drain the system through the valve, ready for the next rain. The bottom of the unit (end cap) can be screwed off to fully clean the unit occasionally. During periods of frequent rain, it may not be necessary to drain the first flush device every time it starts raining as the roof and gutters may already be clean.      

First flush systems work best when a leaf catcher box is installed at the start of the down pipe. The leaf catcher box (available from us) is fitted at the start of the down pipe either directly on the underside of the roof gutter at the fascia board, or to the wall. The device deflects leaves and debris away from the flow of rainwater. 

The below picture shows the ready assembled 110 mm round 4 litre, and 8 litre first flush side by side: (the ready assembled units from us come with a small inspection window in the 110mm pipe). 


 DIY Kit pictures as below:(110mm pipe not included)

 (Kit for 80mm down pipe)

(Kit for 110mm down pipes)

Pictures of ready assembled units (8 litre and 4 litre) - 

Examples of installation outlays:



80mm pipe T Piece (R50) - (*already included in DIY kit)

(T Piece for 110mm pipe R70* - included in 110 First flush kit).



 Leaf Catcher Box (R250) - optional extra.  (adapter for 110 down pipes available)


If you have other shape/size or asbestos existing down pipes we can supply adapters of any size, for example, rectangular to round adapters and reducers etc:


90 degree bend: 

 80 to 110 mm eccentric adapter, R45: (Included in DIY kit).

Rectangular to round adapters:

Plinth bends: 

Adapters for fibre cement down pipes: