The City of Norwood Payneham & St Peters is collecting the rainwater off the roof of the heritage listed Norwood oval grandstand.

Two concrete tanks with a combined capacity of 45,460 litres were installed underground in the car park. The rain water is filtered through mosquito screens to remove dirt and rust as it enters the tanks. From there it is pumped through a 10 micron carbon filter to remove sediment and some chemicals on its way to the Norwood Football Club change rooms for use in the showers, toilets, hand basins and washing machine. A second line, takes it into the adjacent public toilets, for use in flushing and in the hand basins. When the amount of rainwater in storage is insufficient to supply the demands, the pressure pump switches over to allow mains water to be used. With the installation of low flow shower heads, taps and dual flush toilets, 250,000 litres (250 kilo litres), was saved in the first year.

The triple bottom line.

The cost: $50,000 ($42,000 commonwealth grant + $7,000 ratepayers) capital: depreciation $5,000 pa maintenance (filters, gutter cleaning, electric power) $500 pa.

The savings: 250 Kilo litres @ $1.00 per kilo litre equals $250 pa. In a better rainfall year 500 kilo litres may be collected and used.

Cost benefit analysis: reveals a loss of (5000+500)-250 or $5,250 dollars per annum.

Community benefit analysis: is mostly “feel good” and educational.

Environment benefit analysis: is a reduction in storm water runoff and pollution entering the River Torrens. Used water joins the sewage input stream for recycling which probably costs more than the value of the water saved.