a preliminary analysis of potable water savings from ... · 10/16/2009 · effects from internally...
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![Page 1: A Preliminary Analysis of Potable Water Savings from ... · 10/16/2009 · effects from internally plumbed rainwater tanks (e.g. some council regions have enforced rainwater tank](https://reader034.vdocuments.site/reader034/viewer/2022042309/5ed6247424dc623e75223e57/html5/thumbnails/1.jpg)
A Preliminary Analysis of Potable Water Savings from Mandated Rainwater Tanks in New
Residential Properties in SEQ
Cara BealTed Gardner & Ashok Sharma
Decentralised Systems Project
18 August 2009
Urban Water Security Research Alliance
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Background
• Queensland Development Code
• MP4.2 Water savings targets
• January 1 2007
• Savings from mains water of 70kL/household/year
• 70kL..???
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Aim & Methods• Is the 70 kL/hh/year mains water savings target achievable?• Are there demographic and residential features that influence potable water
consumption?• Obtain household water consumption (billing) data from SEQ councils –
Moreton Bay Regional Council, Gold Coast City Council, Redland Shire Council, Ipswich City Council, Sunshine Coast Regional Council
• Data pairs:
• Comparison of the means & two tailed, paired t-test
Criteria Indicator from databaseHouses without mandated rainwater tank
Houses constructed before 2007 (ex. rebates)
Houses with mandated rainwater tanks
Houses constructed after 2007
Similar geographical location Suburb / ABS census district
Similar urban footprint Lot size < or > 700 m2
Similar demographics Suburb / ABS census district (family composition)
V ?
?????
?
?????
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Brisbane
Caboolture Region MBRC
WATER USE MBRC GCCC* RSC
QWC Notification if ≥800L/hh/d
Established gardens/ lawns
– irrigation systems and unattended &/or sprinkler systems
Hand held hose
Hand held bucket &/or watering can
Newly established gardens/lawns
–Irrigation systems, sprinkler systems etc.
Hand held hose
Hand held bucket &/or watering can
Filling up new pools/spas
Once daily
twice daily
Topping up pools/spas & ponds/ aquariums
Car/boat/caravan
General outdoor cleaning
Extremely limited
WATER RESTRICTIONS
* Note GCCC off QWC restrictions between Feb and Nov 08. Jan & Dec as per MBRC restrictions.
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Caboolture Region
Snapshot so far….n = 6,040 pairs
Av. mains use for houses without mandated tanks = 146 kL/hh/year
Av. mains use for houses with mandated tanks = 133 kL/hh/year
Only 1 suburb showed statistically lower water use in post 2007 homes for both lot size categories
Estimated savings for post 2007 homes = 26 kL/hh/year (not statistically significant)
Water use for Caboolture region properties (< 700m2) for period Jan to Dec 2008
0
20
40
60
80
100
120
Bon
gare
e
Nar
angb
a
Cab
ooltu
re
Mor
ayfie
ld
Sand
ston
ePo
int
Ban
ksia
Bea
ch
Bea
chm
ere
Bel
lmer
e
Woo
rim
Dec
eptio
nB
ay
Ave
rage
tota
l wat
er c
onsu
mpt
ion
(kL/
hh/s
ix m
onth
s)
Houses without mandated tanksHouses with mandated tanks
n=3
48
n=21
3
n=15
0
n=57
5
n=56
0
n=53
0
n=16
9
n=14
0
n=93
n=27
5
Water use for Caboolture region properties (> 700m2) for period Jan to Dec 2008
0
20
40
60
80
100
120
Bon
gare
e
Nar
angb
a
Cab
ooltu
re
Mor
ayfie
ld
Sand
ston
ePo
int
Ban
ksia
Bea
ch
Bea
chm
ere
Bel
lmer
e
Woo
rim
Dec
eptio
nB
ay
Ave
rage
tota
l wat
er c
onsu
mpt
ion
(kL/
hh/s
ix m
onth
s)Houses without mandated tanksHouses with mandated tanks
n=1
52
n=85
3
n=18
9
n=50
0
n=48
8
n=18
7
n=74
n=93
n=10
5
n=34
7
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-30 -20 -10 0 10 20 30 40
Average annual savings (kL)
Bongaree (n=500)
Narangba (n=1066)
Caboolture (n=1048)
Morayfield (n=1075)
Sandstone Point (n=339)
Banksia Beach (n=621)
Beachmere (n=198)
Bellmere (n=233)
Woorim (n=243)
Deception Bay (n=717)
Average annual savings (kL) Jan to Dec 2008 for all properties from selected suburbs in Caboolture area (Moreton Bay Regional Council)
Properties < 700m2 Properties >700 m2
av. 25.9 kL combined
Estimated savings for Caboolture region
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Brisbane
WATER USE MBRC GCCC* RSC
QWC Notification if ≥800L/hh/d
Established gardens/ lawns
– irrigation systems and unattended &/or sprinkler systems
Hand held hose
Hand held bucket &/or watering can
Newly established gardens/lawns
–Irrigation systems, sprinkler systems etc.
Hand held hose
Hand held bucket &/or watering can
Filling up new pools/spas
Once daily
twice daily
Topping up pools/spas & ponds/ aquariums
Car/boat/caravan
General outdoor cleaning
Extremely limited
WATER RESTRICTIONS
* Note GCCC off QWC restrictions between Feb and Nov 08. Jan & Dec as per MBRC restrictions.
Gold Coast City Council
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Snapshot so far…
n = 1,944 pairs
Av. mains use for houses without mandated tanks= 188 kL/hh/year
Av. mains use for houses with mandated tanks = 167 kL/hh/year
All post 2007 homes had significantly lower water use for <700 m2
Estimated savings for post 2007 homes = 38 kL/hh/year
Outdoor water use less restricted in GCCC – greater expression of differences between mandated & non mandated houses
Gold Coast City Council
Water use for GCCC for period Jan 2008 to Jan 2009
0
10
20
30
40
50
60
2008/09Q1
2008/09Q2
2008/09Q3
2008/09Q4
2008/09Q1
2008/09Q2
2008/09Q3
2008/09Q4
Lot size < 700m2 Lot size > 700m2
Qua
rterly
wat
er c
onsu
mpt
ion
(kL)
Houses without mandated tanks
Houses with mandated tanks
n=139 per quartern=347 per quarter
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-10 0 10 20 30 40 50 60
Quarterly water consumption (kL)
2008/09 Q1
2008/09 Q2
2008/09 Q3
2008/09 Q4
2008/09 Q1
2008/09 Q2
2008/09 Q3
2008/09 Q4
Lot s
ize
< 70
0m2
Lot s
ize
> 70
0m2
Estimated average savings from mains water in GCCC over the period Jan 2008 to Jan 2009
Quarterly savings
Annual savings
av. 38 kL combined
Estimated savings for Gold Coast
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Brisbane
Redland Shire Council
WATER USE MBRC GCCC* RSC
QWC Notification if ≥800L/hh/d
Established gardens/ lawns
– irrigation systems and unattended &/or sprinkler systems
Hand held hose
Hand held bucket &/or watering can
Newly established gardens/lawns
–Irrigation systems, sprinkler systems etc.
Hand held hose
Hand held bucket &/or watering can
Filling up new pools/spas
Once daily
twice daily
Topping up pools/spas & ponds/ aquariums
Car/boat/caravan
General outdoor cleaning
Extremely limited
WATER RESTRICTIONS
* Note GCCC off QWC restrictions between Feb and Nov 08. Jan & Dec as per MBRC restrictions.
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Redland Shire Council Snapshot so far…
n = 3,920 pairs
Av. mains use for houses without mandated tanks = 212 kL/hh/year
Av. mains use for houses with mandated tanks = 112 kL/hh/year
All post 2007 homes had significantly lower water use for <700 m2
Estimated savings for post 2007 homes = 80 kL/hh/year
Outdoor water use less restricted in RSC – greater expression of differences between mandated & non mandated houses
Water use in Redlands Shire for properties < 700 m2 over the period April 2007 and March 2009
0
10
20
30
40
50
60
2007 AprJun
2007 JulSep
2007 OctDec
2008 JanMar
2008 AprJun
2008 JulSep
2008 OctDec
2009 JanMar
Billing Quarter
Aver
age
tota
l wat
er c
onsu
mpt
ion
(kL/
hh/q
uart
er)
Houses without mandated tanksHouses with mandated tanks
n=21
n=72
n=17
0
n=26
4
n=38
1
n=46
8
n=54
7
n=63
8
Water use in Redlands Shire for properties > 700 m2 over the period April 2007 and March 2009
0
10
20
30
40
50
60
70
80
90
100
2007 AprJun
2007 JulSep
2007 OctDec
2008 JanMar
2008 AprJun
2008 JulSep
2008 OctDec
2009 JanMar
Billing Quarter
Aver
age
tota
l wat
er c
onsu
mpt
ion
(kL/
hh/q
uart
er)
Houses without mandated tanksHouses with mandated tanks
n=16
n=36
n=76
n=13
2
n=19
9
n=24
1
n=30
6
n=35
3
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Estimated average savings from mains water in Redlands Shire over the period April 2007 and March 2009
0 20 40 60 80 100 120 140 160
2007 Apr Jun
2007 Jul Sep
2007 Oct Dec
2008 Jan Mar
2008 Apr Jun
2008 Jul Sep
2008 Oct Dec
2009 Jan Mar
Savings (kL/hh/quarter)
Annual savings >700m2Quarterly savings >700m2Annual savings <700m2Quarterly savings <700m2
av. 80 kL combined
Estimated savings for Redland
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Internal water use & estimated savings
Perth -
155 L/pp/day Yarra Valley –
169 L/pp/day
Bath/Shower
Leaks
Other
Tap
Toilet
Washing machine
24%33% 31%
27%21%
16%
3%
18%16%
9%2%
Bath/Shower
Leaks
Other
Tap
Toilet
Washing machine
• Toilet + laundry = average 45% of internal water use (73 L/p/d)
= 71 kL/hh/year
savings from mains water (assuming full tank)
• Caboolture –
26 kL/hh/year• Redlands –
80 kL/hh/year
• Need modelling to identify tank capacities and savings under range of scenarios
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Further considerations / work…
• Rebate tanks to be excluded from dataset
• ABS Census district data – allows for greater resolution in pairing homes and teasing out demographic influences on domestic water use
• Teasing out effects of restrictions, rebates and Waterwise features v effects from internally plumbed rainwater tanks (e.g. some council regions have enforced rainwater tank installation prior to 2007 (e.g. Pine Rivers)
• Roof and tank size will affect rainfall & volume
• Garden size / lawn area more relevant parameters than lot size in gauging outdoor water use, although data much harder to obtain
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Thank youwww.urbanwateralliance.org.au