Rainwater-tank rebates for households and businesses are unlikely to provide value for money for the Tweed shire, according to council managers.
That’s one of the main grounds why Tweed Shire Council staff have recommended not to proceed with a rebate plan in a revision to its rainwater tank policy to be debated by councillors tomorrow night (Thursday).
Instead, staff recommend looking at other demand-management programs, such as a non-residential rebate on dual flush toilets, showers and tapware, which they say would be ‘more reliable and more cost effective’.
The move coincides with Rous Water, which supplies the Tweed’s neighbouring shires with drinking water, doubling its existing rebates for residents who buy and install rainwater tanks at their homes.
Rebates for different-sized types of tanks amounting to between $200 and $1,000 came into effect in those local-government areas on April 1, and was twice the previous offer for residents connected to town water in Byron, Ballina, Lismore or Richmond Valley.
In his report, council’s engineering director David Oxenham also recommended scrapping a voluntary online rainwater tank register started two years ago, to evaluate tanks installed in the shire as part of demand management strategy would be ‘little or no value’ to council.
Mr Oxenham also said there was no need for a separate policy for tanks (non-potable water harvesting) in commercial and industrial precincts, only amending the existing policy for rainwater tanks in urban areas to cater for their use.
He said that council resolved in August 2011 to consider rebate schemes for rainwater tanks, but that ‘evidence from tank rebate schemes implemented elsewhere confirms that they generally don’t provide the best value for money’.
‘While rainwater tanks are recognised as a way to augment household or business water supply, studies have shown that the exact degree to which they reduce water demand is highly variable.
‘Results ranging from 10 to 100kL/a (average kilolitres) per household have been reported.
‘It is therefore considered that a tank rebate scheme is not effective and need not be considered further.’
Mr Oxenham also said the cost of of carrying out a Tweed Shire specific evaluation of rainwater tank rebates was prohibitive.
‘The development of a voluntary tank register was considered as a way of collecting background data but this would cost in the vicinity of $10,000 to setup and $10,000-$20,000 per year to promote and administer.
‘Despite this, data in the voluntary register would be inherently unreliable. On-site inspections of rainwater tanks would be required to refine the data in the register and this would cost about $30,000 per year in additional staff resources.
‘Analysis of the data would have to be outsourced and would require sophisticated statistics costing a further $10,000 to $20,000.
‘In total, evaluating the likely effectiveness of a tank rebate could cost up to $100,000 and the results would still have a high degree of uncertainty.
‘The likely finding of such an analysis would be that tank rebates are not cost effective.
‘The conclusion is that even though a community survey conducted in May 2012 clearly indicated that a council rebate for tanks would be well received and supported, such a rebate is unlikely to provide value for money.
‘Other demand management programs, such as a non-residential rebate on dual flush toilets, showers and tapware would be more reliable, less cost and provide more water saving.’