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Water Consumption Research Project

No contact households (Phase 3)

August 2014

Background

• This phase of WCRP was conducted to analyse

the ‘no contact’ households from Phase 1

• No contact means the door was not answered

when the market researcher visited

• Purpose of this study is to determine if water

consumption is different in no contact households

Methodology

• Targets the no contact households from Phase 1

– Target sample identified 5,790 households

• circa 4 months meter readings
• Consumption per day calculated as total

metered quantity divided by number of days from date of install to date of meter read.

Methodology

• Door to door survey carried out by market research

company

• On this occasion surveys were conducted later on

weekdays and on two Saturdays

• Sensitive sites removed from list
• Data collected:

– Architecture type – Number of bedrooms – Number of occupants per house, including adults and children

• Assumption that surveys are answered and

recorded honestly and in good faith

• No data on socio-economic profile or age of

respondents

• Sample selection limited to households that had

meters installed before December 2013

• Mostly suburban areas – reflects installed

meters

Limitations

Assumptions

• Households greater than 800 litres/day removed

using the same methodology as the initial study

• Household usage is most closely correlated with
• ccupancy
• Children are defined as children under 18 living in

the household.

• Sample is not representative of CSO population

census but provides a useful snapshot of households metered so far

• Annual consumption is extrapolated from available

data

1A total of 23 outliers were removed.

Survey sample (ex outliers)

Children 1 2 3 4 5 Total Adults 1 31 10 2 1 1 45 2 117 58 78 33 6 3 295 3 34 9 8 5 56 4 17 3 3 2 25 5 5 1 6 6 1 1 Total 205 80 92 41 6 4 428

Sample geographic distribution

• 12
• 10
• 8
• 6
• 4

52 53 54 55 Longitude Latitude

Survey validation

CSO WCRP

1 occupant 24% 7% 2 occupants 29% 30% 3 occupants 18% 22% 4 occupants 16% 25% 5 occupants 9% 11% 6 + occupants 4% 5% Apartment 9% 1% Terraced 17% 16% Semi-detached 28% 39% Detached3 42% 43%

2Bungalows added to detached households as CSO does not use bungalow as a classification

Comparison of survey household proportions to CSO census data:

Survey validation

CSO WCRP

Apartment

2.0 1.5

Terraced

2.5 3.1

Semi-detached

2.8 3.3

Detached

3.0 3.2

Total

2.7 3.2 Comparison of survey household size (occupancy) to CSO census data:

Data distribution (ex outliers)

litres per person per day Frequency 100 200 300 400 10 20 30 40 50

3D scatterplot

1 2 3 4 5 6 200 400 600 800 1 2 3 4 5

Adults Children litres per household per day + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +

Phase 1 vs Phase 3

Phase 1 No contact (phase 3)

Sample size litres/person Sample size litres/person 1 occupant 94 171 31 123 2 occupants 335 140 127 123 3 occupants 353 108 94 100 4 occupants 428 94 105 87 5 occupants 265 83 49 86 6 + occupants 111 84 22 83 Total 1,586 428 Detached 435 110 186 101 Semi-detached 748 106 166 101 Terraced 370 109 70 111

Phase 1 vs Phase 1 & 3

Phase 1 Phase 1 & 3

Sample size litres/person Sample size litres/person 1 occupant 94 171 125 159 2 occupants 335 140 462 135 3 occupants 353 108 447 106 4 occupants 428 94 533 93 5 occupants 265 83 314 83 6 + occupants 111 84 133 84 Total 1,586 2,014 Detached 435 110 621 107 Semi-detached 748 106 914 105 Terraced 370 109 440 110

CSO weighted average

• Overall average consumption/person in

WCRP study can be weighted to CSO census data

• Multiply the WCRP average litres/person for

each occupancy by the number of people living in households3 with the same level of

• ccupancy.
• Divide the resulting litres consumed

nationally by the population that have a public mains connection

3Household with public mains connection as per CSO Census 2011

CSO weighted average Phase 3

• Weighted average: 100 litres per person per day

Occupancy A - CSO Households B - CSO Occupants C - litres/person National/litres (B * C) 1 occupant 302,967 302,967 123 37,176,885 2 occupants 369,976 739,952 123 90,939,780 3 occupants 225,130 675,390 100 67,245,469 4 occupants 198,002 792,008 87 69,005,960 5 occupants 101,926 509,630 86 43,589,257 6 + occupants 49,184 316,125 83 26,183,819

Total 1,247,185 3,336,072 100 334,141,171

CSO weighted average Phase 1 & 3

• Weighted average: 109 litres per person per day

Occupancy A - CSO Households B - CSO Occupants C - litres/person National/litres (B * C) 1 occupant 302,967 302,967 159 48,171,753 2 occupants 369,976 739,952 135 99,893,520 3 occupants 225,130 675,390 106 71,591,340 4 occupants 198,002 792,008 93 73,656,744 5 occupants 101,926 509,630 83 42,299,290 6 + occupants 49,184 316,125 84 26,554,500

Total 1,247,185 3,336,072 109 362,167,147

Summary

• CSO census weighted phase 3 water consumption per

person per day is lower

– this needs to be considered in the context of a smaller sample size

• When Phase 1 and 3 are added together the CSO

weighted average is close to the 111 litres per person per day previously reported

• Biggest difference is for one and two occupant

households

– Possibly due to the occupiers being outside of the home more often, e.g. young professionals

• Incremental usage is in line with the proposed child

allowance