SUPADIVERTA - syphonic rainwater diverter

FEATURES

THE PRACTICAL REALITY

First flush diverters are more effective harvesting tin rooves than when harvesting tile rooves. Tin rooves drain faster, their smooth surfaces are quickly washed and the generated heat can have a sterilising effect on bird droppings and other contaminants.
Tiled rooves are numerically the most popular but their rougher and often weathered surfaces and grooves makes natural roof washing a slower process.
Domestic first flush divert chambers are commonly 90mm or 100mm PVC pipes which hold 5.8 and 8.2 litres respectively for each one metre length. For reasons both practical and aesthetic, most domestic units are rarely more than 1.5 metres long; therefore 1.5 metre lengths of 90mm and 100mm PVC pipe hold about 8.7 litres and 12.3 litres respectively.
Recommended first flush capacities vary between .5mm to 2mm for each square metre of roofing harvested. Given that large amounts of solid pollutants are not immediately washed from rooves and gutters, the average domestic first flush diverter is expected to perform a minor miracle.
The initial first flush contains the most contaminated water and a first flush diverter is a recommended accessory but homeowners need to be aware of practical limitations and not expect miracles.

The Cooperative Research Centre (CRC) for Water Quality and Treatment research report 39 (Guidance Manual for the design and installation of urban roofwater harvesting systems in Australia) states that research has shown first flush results are variable at best and particulates have been detected throughout the entire rainfall event(s). This coincides with AQUATREK’S studies over a two year period.

The research report; RAINWATER FIRST FLUSH DEVICES – ARE THEY EFFECTIVE? Gardner, Baisden, Millar, (2004) quotes percentage reductions for bacterial loads, suspended solids and trace metal contaminants when using first flush diverters and is interesting reading.

Unfortunately, many reports lack detail including the type and slope of roof, roof area harvested, rainfall intensities, gutter gradient, time period between rain (test) events and the observed influence of those periods on test results.

Rainwater quality and the retardation of tank sediment build up improves substantially when solid bird droppings and other particulates are continuously diverted by the SUPADIVERTA’S internal 750 micron divert filter.