Rainwater Harvesting in South-East Queensland: The Case for Public Investment

In this submission to the Queensland Water Commission on the South East Queensland Water Strategy, Water Planning Tools researcher Dr Ian White provides clear evidence of the yields obtainable from household rainwater harvesting, and economic, social and environmental arguments for the Queensland Government to re-establish its support for rebates to household installation of rainwater harvesting systems as part of an integrated water supply and security management framework.

He argues that the withdrawal of support for rainwater harvesting as an alternative supply mechanism demonstrates a failure of evidence-based decision making and, particularly, a failure of the South East Queensland Water Strategy to consider a most obvious and economically, socially and environmentally sustainable source of water for supplementing and securing South East Queensland’s urban supply.

Summary

rainwater-harvesting-150x150 Based on recent, local, high-quality research, through a survey of 560 South East Queensland homes, the author submits to the consideration of the Queensland Government, two primary and ten subsidiary policy recommendations in support of rainwater as a decentralised supplement to the reticulated mains supply in South East Queensland. In considering submissions made to the South East Queensland Water Strategy, it is strongly recommended that the Queensland Water Commission and the Queensland Government consider a decision to reinstate the Home Waterwise Rebate Scheme, or an equivalent scheme that rebates households for the installation of rainwater harvesting systems. The benefits to Queensland’s water supply will be most effective if this rebate scheme is effective in encouraging households to connect the rainwater harvesting system to the toilet, laundry and hot water service, none of which require the harvested water to be treated to potable standard, and the increased demand from which will assure that the water stored in the tank is subject to daily demand, maximising yield.

Additionally, the effectiveness of these rainwater harvesting systems will be maximised when the security of supply provided by these rainwater harvesting systems is assured by establishing a supplementary connection to the mains supply through commercially available switching devices that allow rainwater to be the primary supply, with the mains supply available as a back-up.

The South East Queensland community is clearly a willing partner in the supplementation of the mains supply through household rainwater harvesting. The further proliferation of rainwater harvesting systems in Queensland homes is a cost-effective, high yielding, high quality, safe, environmentally friendly and socially desirable initiative in further securing South East Queensland’s urban water supply.

Policy Recommendations

Proposal 1: It is recommended that rainwater harvesting rebate schemes be maintained indefinitely. Rainwater harvesting shows clear benefits against triple bottom line assessments and is the most cost effective means for Governments to provide increased water security.

Proposal 2: It is recommended that a range of governance issues be addressed to increase the effectiveness of rainwater harvesting systems, protect public health and maximise reductions in mains water demand. In relation to this, it is recommended that:

an additional means-tested subsidy would be helpful in assisting lower income households with the costs of RH installation.
any additional action to address water consumption in Government owned housing should consider the clear cost benefit advantages of RH in comparison with other water supply technologies to maximise reductions in mains water demand.
a review of the complex taxation demands on RH system acquittals should be given some priority to simplify the system and minimise incorrect claims.
the existing opportunity for relaxation of RH system siting constraints should be made more prominent in the Council literature on RH adoption and that Councils be provided with a clear set of guidelines that enable a culture of approval.
the National Water Commission should secure a statement from the Australian Government that no future levy will be imposed on RH installations due to Australian Government ownership of the airspace.
although there is clear community support for mandated RH adoption under the Queensland Development Code, households should otherwise retain sovereignty over an RH adoption decision.
the RH rebate scheme conditions be modified increase the minimum storage size from 3kL to at least 5kL, and ideally 10kL to maximise to reductions in mains water demand.
attention should be given to publicising the deleterious health effects of lead (Pb) in the catchment area, since direct consumption of harvested rainwater continues despite commonly adopted RH system components not being capable of removing lead.
existing limitations on the connection of rainwater to household hot water services should be removed to maximise to reductions in mains water demand.
the risk of infection caused by RH backflow to the reticulated mains should be reassessed and the requirement for multiple backflow prevention devices removed, lowering the cost barrier to installation of more sophisticated RH systems with capacity to maximise reductions in mains water demand.