Quantifying mains water savings from residential rainwater tanks

Turner, A; Fyfe, J

Quantifying mains water savings from residential rainwater tanks

Turner, A

Fyfe, J

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Publisher:: International Water Association
Publication Type:: Chapter
Citation:: Rainwater Tank Systems for Urban Water Supply, 2015, 1, pp. 47-72
Issue Date:: 2015-03-01

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Field	Value	Language
dc.contributor.author	Turner, A https://orcid.org/0000-0002-0586-5615
dc.contributor.author	Fyfe, J
dc.contributor.editor	Sharma, A
dc.contributor.editor	Begbie, D
dc.contributor.editor	Gardner, T
dc.date.accessioned	2023-12-01T21:47:05Z
dc.date.available	2023-12-01T21:47:05Z
dc.date.issued	2015-03-01
dc.identifier.citation	Rainwater Tank Systems for Urban Water Supply, 2015, 1, pp. 47-72
dc.identifier.uri	http://hdl.handle.net/10453/173642
dc.description.abstract	The premise for mandating rainwater tanks, or implementing expensive financial incentive programs such as rebates for the installation of tanks, is that meaningful savings can be achieved from the potable water supply. Whilst there is a depth of literature on modelled and theoretical savings from rainwater tanks, there are scant studies that seek to quantify the savings from multiple household ‘real life’ examples. The primary objective of this chapter is to present three different methods for assessing the savings in mains water use from regions of Australia that have recently installed rainwater tanks. We believe all three methods are internationally applicable. Various ‘before’ and ‘after’ comparisons are presented of mains water demand resulting from either rebated or mandated rainwater tank installations. Case Study 1 is a desktop assessment that uses water utility water billing data, lot sizes and presence or absence of an internally plumbed rainwater tank (RWT) to make pair-wise statistical inferences on the range of savings from internally plumbed tanks at a scale of local authority areas. Building on Case Study 1, Case Study 2 applies known household socio-demographic data matched with their household billing data to determine a benchmark water savings. Case Study 3 focuses on the water savings derived from a city-wide rainwater tank rebate program by comparing water consumption of each individual rebated household with a statistically-matched non-rebated household. Conclusions from all the studies focus on the need for sufficiently large sample sizes, known household occupancy, and the penetration of water efficient appliances in households. Comparison of savings estimates highlighted the variability of rain tank yields between regions associated with climate, tank sizes and functionality, and connected end uses and roof area. Outdoor consumption is a critical end-use that will maximise savings. Thus factors such as potable water restrictions, lot size and behavioural cues (willingness to water use) are also important in determining water savings.
dc.format.extent	14
dc.language	en
dc.publisher	International Water Association
dc.relation.ispartof	Rainwater Tank Systems for Urban Water Supply
dc.rights	info:eu-repo/semantics/openAccess
dc.title	Quantifying mains water savings from residential rainwater tanks
dc.type	Chapter
utslib.citation.edition	1
pubs.organisational-group	/University of Technology Sydney
pubs.organisational-group	/University of Technology Sydney/DVC (Research)
pubs.organisational-group	/University of Technology Sydney/DVC (Research)/Institute For Sustainable Futures
pubs.organisational-group	/University of Technology Sydney/Strength - ISF - Institute for Sustainable Futures
utslib.copyright.status	open_access	*
pubs.consider-herdc	false
dc.date.updated	2023-12-01T21:47:04Z
pubs.edition	1
pubs.place-of-publication	London
pubs.publication-status	Published
dc.location	London

Abstract:

The premise for mandating rainwater tanks, or implementing expensive financial incentive programs such as rebates for the installation of tanks, is that meaningful savings can be achieved from the potable water supply. Whilst there is a depth of literature on modelled and theoretical savings from rainwater tanks, there are scant studies that seek to quantify the savings from multiple household ‘real life’ examples. The primary objective of this chapter is to present three different methods for assessing the savings in mains water use from regions of Australia that have recently installed rainwater tanks. We believe all three methods are internationally applicable. Various ‘before’ and ‘after’ comparisons are presented of mains water demand resulting from either rebated or mandated rainwater tank installations. Case Study 1 is a desktop assessment that uses water utility water billing data, lot sizes and presence or absence of an internally plumbed rainwater tank (RWT) to make pair-wise statistical inferences on the range of savings from internally plumbed tanks at a scale of local authority areas. Building on Case Study 1, Case Study 2 applies known household socio-demographic data matched with their household billing data to determine a benchmark water savings. Case Study 3 focuses on the water savings derived from a city-wide rainwater tank rebate program by comparing water consumption of each individual rebated household with a statistically-matched non-rebated household. Conclusions from all the studies focus on the need for sufficiently large sample sizes, known household occupancy, and the penetration of water efficient appliances in households. Comparison of savings estimates highlighted the variability of rain tank yields between regions associated with climate, tank sizes and functionality, and connected end uses and roof area. Outdoor consumption is a critical end-use that will maximise savings. Thus factors such as potable water restrictions, lot size and behavioural cues (willingness to water use) are also important in determining water savings.

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http://hdl.handle.net/10453/173642