Calculation and Sensitivity Analysis of y ythe Infrastructure Leakage Index for

UK Water CompaniesUK Water Companies

Aaron BurtonAaron Burton

IWA UK Young Water Professionals ConferenceNewcastle, April 2008

Outline

• Background• Methods• 2006/07 UK ILI Results• Comparison with ELL• Sensitivity Analysis• Sensitivity Analysis• Conclusions and further

hresearch

Background – Leakage

6000e

Historical Total Leakage Target Total Leakage

3000

4000

5000

nies

Lea

kage

1000

2000

3000

ater

Com

pan

Ml/d

0

94-9

595

-96

96-9

797

-98

98-9

999

-00

00-0

101

-02

02-0

303

-04

04-0

505

-06

06-0

707

-08

08-0

909

-10

Tota

l UK

Wa

199

199

199

199

199

199

200

200

200

200

200

200

200

200

200

200

*Adapted from OFWAT Security of Supply 2006/07 ReportAdapted from OFWAT Security of Supply 2006/07 Report

Background - ILI

• International Water Association (IWA) Standard MethodologyMethodology

ILI = CARL/ UARLInfrastructure leakage index = Current Annual Real Losses/ Unavoidable Annual

Real Losses

• Utilised internationally and free software developedUtilised internationally and free software developed• Controversy in the UK = does not account for

environmental, social or economic factors implicitly , p yand does not account for pressure management

• Standard in USA, Australia, South Africa, others...

Methods – AWWA WaterMethods – AWWA Water Audit Software

OFWAT J R t 2006/07 d t il blWater Audit Report for: DCWW - N Eryri / Ynys Mon

Reporting Year:

All volumes to be entered as: MEGALITRES (THOUSAND CUBIC METRES) PER YEAR

WATER SUPPLIEDVolume from own sources: 16,662.250 Megalitres/yr (or ML/Yr)

Master meter error adjustment: ML/YrWater imported: 0.000 ML/Yr

Water exported: 149.650 ML/Yr.

WATER SUPPLIED: 16,512 600 ML/Yr

AWWA WLCC Water Audit Software: Reporting Worksheet

2006/07

?

? Click to access definition

Back to Instructions

Please enter data in the white cells below. Where possible, metered values should be used; if metered values are unavailable please estimate a value. Indicate this by selecting a choice from the gray box to the left, where M = measured (or accurately known value) and E = estimated.

???

Copyright © 2006, American Water Works Association. All Rights Reserved. WASv3.0

• OFWAT June Return 2006/07 data available on website• AWWA Water Audit Software• Modelled supply pipe lengths based on L/N vsWATER SUPPLIED: . 16,512.600 ML/Yr.

.AUTHORIZED CONSUMPTION .

Billed metered: 5,902.050 ML/YrBilled unmetered: 6,128.350 ML/YrUnbilled metered: 153.300 ML/Yr Pcnt: Value:

Unbilled unmetered: 113.150 ML/Yr 1.25%.

AUTHORIZED CONSUMPTION: . 12,296.850 ML/Yr

.WATER LOSSES (Water Supplied - Authorized Consumption) . 4,215.750 ML/Yr

.Apparent Losses . Pcnt: Value:

Unauthorized consumption: 0.000 ML/Yr 0.25%Customer metering inaccuracies: 0.000 ML/Yr 2.00%Systematic data handling errors: ML/Yr

Apparent Losses: . 0.000 ML/Yr

Real Losses

113.150

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?

?

?

?

?

?

Use buttons to selectpercentage

ORvalue

?Click here: for help using option buttons below

• Modelled supply pipe lengths based on L/N vs. Zero supply pipe length• Modelled pressure based on AZNP vs. 50m standardReal Losses .

Real Losses = (Water Losses - Apparent Losses): . 4,215.750 ML/Yr.

WATER LOSSES: . 4,215.750 ML/Yr..

NON-REVENUE WATER .NON-REVENUE WATER: . 4,482.200 ML/Yr

.

SYSTEM DATA ..Length of mains: 1,614.0 kilometers

Number of active AND inactive service connections: 61,580Connection density: . 38 conn./km main

Average length of customer service line: 16.1 metres

.Average operating pressure: 50.4 metres (head)

.COST DATA ..

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(pipe length between curbstop and customer meter or property boundary)

Water Audit Report For: Report Yr:

DCWW - N Eryri / Ynys Mon 2006/07

Water Exported

149.650Billed Metered Consumption (inc. water exported)

Revenue Water

5,902.050

AWWA WLCC Water Audit Software: Water Balance

Billed Authorized Consumption

Billed Water Exported

Copyright © 2006, American Water Works Association. All Rights Reserved. WASv3.0

standard

Total annual cost of operating water system: $/Year

Customer retail unit cost (applied to Apparent Losses):Variable production cost (applied to Real Losses): $/Megalitre

DATA REVIEW - Please review the following information and make changes above if necessary:

- Input values should be indicated as either measured or estimated. You have entered:

0 as measured values 0 as estimated values 0 as default values 18 without specifying measured, estimated or default

- Water Supplied Data: No problems identified

- Unbilled unmetered consumption: No problems identified

- Unauthorized consumption: No problems identified

- It is important to accurately measure the master meter - you have entered the measurement type as: unspecified

- Cost Data: None to evaluate

?

?

?Own Sources

Authorized Consumption 12,030.400 Billed Unmetered Consumption 12,030.400

6,128.35012,296.850 Unbilled Metered Consumption

153.300

16,662.250 266.450 Unbilled Unmetered Consumption

113.150Water Supplied Unauthorized Consumption 4,482.200

Apparent Losses 0.00016 512 600 0 000 Customer Metering Inaccuracies

Non-Revenue Water (NRW)

Unbilled Authorized Consumption

(Adjusted for known errors)

Cost Data: None to evaluate

PERFORMANCE INDICATORS

Financial IndicatorsNon-revenue water as percent by volume: 27.1%

Non-revenue water as percent by cost:Annual cost of Apparent Losses:

Annual cost of Real Losses:

Operational Efficiency Indicators

Apparent Losses per service connection per day: 0.00 litres/connection/day

Real Losses per service connection per day*: 187.56 litres/connection/day

Real Losses per length of main per day*: N/A

Real Losses per service connection per day per meter (head) pressure: 3.72 litres/connection/day/m

Unavoidable Annual Real Losses (UARL): 1,895.16 cubic meters/year?

16,512.600 0.000 Customer Metering Inaccuracies

0.000Systematic Data Handling Errors

Water Losses 0.000

Water Imported 4,215.750 Leakage on Transmission and/or Distribution Mains

Real Losses Not broken down

0.000 4,215.750 Leakage and Overflows at Utility's Storage Tanks

Not broken downLeakage on Service Connections

2.22

* only the most applicable of these two indicators will be calculated

Infrastructure Leakage Index (ILI) [Real Losses/UARL]:?

Leakage on Service Connections

Not broken down

Sensitivity AnalysisSi l th d M t d R k i l th d• Simple method = Macro to produce

percentage change for individual parameters and observe relative change in ILI value

•Rank equivalence method = percentage change in parameter to cause change in rank

Companies ILI Rank

123 DCWW

in ILI value

3 DCWW45678

CARL/ UARL

PARAMS

Any

cha

nge

in

rank

910

Companies ILI Rank

12iti

on3 DCWW45678

CARL/ UARL

PARAMS

Sw

ap p

os

910

ILI for UK Companies 50m PressureILI for UK Companies – 50m Pressure, Zero Service Pipe Length

4.224.50

3.373.50

4.00

L)

2.72

2.48 2.462.36

2.192.05

2.50

3.00

ILI (

CAR

L/U

ARL

Mean 1.87M di 1 641.92

1.81 1.80 1.75

1.53 1.50 1.41 1.40 1.38 1.38 1.331.29 1.20 1.14 1.11 1.04

1 00

1.50

2.00Median 1.64

0.00

0.50

1.00

0.00

Water Company*Distribution losses up to the property

line - UARL does not include real losses on metered and unmetered

2006/07 2001/02 Mean (2006/07)private pipes after the property line

ILI Vs % volume input andILI Vs % volume input and l/conn/d traditional indicators

25%

30%

35%

200

250

15%

20%

NRW

 % inpu

t volum

e

100

150

l/conn

/d

0%

5%

10%

0 00 0 50 1 00 1 50 2 00 2 50 3 00 3 50 4 00 4 500

50

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50

ILI0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50

ILI

• Strong correlation between ILI and non-revenue water as a % of input volume (R2=0 98) however ILI accounts for system specific factorsvolume (R2 0.98), however, ILI accounts for system specific factors• Strong correlation between ILI and litres/ connection/ day (R2=0.92)

ILI for UK Companies ModelledILI for UK Companies – Modelled Pressure and Zero Service Pipe Length

COMPANY AOP ( )COMPANY AOP (m)C 58R 52F 51M 48

4.884.7

5

6

ce pipe lengths

D 45J 45T 43A 43G 43

3.56

4

odelled AZN

P and servi

G 43H 42S 42L 41W 41K 41

2.742.65

2.532.43 2.42 2.36 2.3

2.112.01

1.89 1.81 1 782

3

Calculated

 based

 on mo

Mean: 2.42

K 41V 40I 40O 39Q 39

.8 1.781.6

1.51.36 1.32

1

ILI C

B 36E 35N 30U 23

0

Water Companies

Comparison with ELL/ReportedComparison with ELL/Reported Volumes

90063.33

9003.5

4.884.7

3.56

500

600

700

800

4

5

kage

 (Ml/d)

Supp

ly PIpe)

2.55

2.081.96

500

600

700

800

2

2.5

3

(Ml/d)

y pipe

 length)

2.74 2.652.53

2.43 2.42 2.36 2.32.11

2.011.89 1.81 1.78

1.61.5

1.36 1.32200

300

400

1

2

3

Repo

rted

 and

 ELL lea

ILI (50m pressure; 0m S 1.83 1.81

1.75 1.74 1.7 1.65

1.51.43

1.351.29 1.28

1.14 1.090.97 0.95

200

300

400

500

1

1.5

Repo

rted

 and

 ELL Leakage

 

mod

elled pressure and

 supp

l y

0

100

0

1

ILI 2006/07 Ml/d

0

100

0

0.5

ILI (

ILI 2006/07 Ml/d 2009/10 Target Ml/d

• Modelled pressure results in a stronger correlation between ILI and reported leakage volumes, especially for company B and C (R2=0.83 vs 0.81)• Difference between ELL/ reported volumes for companies with similar ILI values =Difference between ELL/ reported volumes for companies with similar ILI values links with ILI not reflecting environmental and economic factors that are included in the assessment of volumetric targets

ILI Dataset Comparison90

10

79

7170

80

8.9

7.3

4.8

3 8

5

6

7

8

9

e Leakage Inde

x (CARL/U

ARL)

50

40

50

60

RL/U

ARL)

3.8

2.42 2.3 2.2 2.1 2.1 21.7 1.7 1.65 1.6 1.6 1.6 1.4 1.3 1.3 1.3 1.2 1.1 1 0.93 0.8

0

1

2

3

4

Infrastructure

40 39

31

27 2724

30

40

ILI (CA

R

Water Utility

1816 16 15 15

11 10 10 9.7 97.1 6.7 5.7 5.7 5 4.1 3.6 3.4 2.5 2.42 2.4 2.1 1.65 1.5 1.3 1.2 1.2

0

10

20

0

Vietnam

Russia

Turkey

Turkey

Sri Lanka

Indo

nesia

Jordan

Malaysia

Bulgaria

Costa Rica

Italy

Greece

Hun

gary

Turkey

Sri Lanka

South Africa

Carib

bean

Greece

Ukraine

Italy

Czech Re

p.

Hun

gary

South Africa

Ireland

Japan

New

 Zealand

Czech Re

p.

France

2006/07 UK  …

Germany

UK

006/07 UK LO

W UK

UK

Australia

New

 Zealand

Country

20

Sensitivity AnalysisSensitivity AnalysisSimple Method

% Change A C XVolume from own sources +/‐2% ‐5.75% ‐13% ‐25%Water Imported +/‐2% ‐1% 0% 0%

/

ParameterComment

ILI % Change (higher value)

Water exported +/‐2% 0% 3% 0%Billed metered +/‐1% DI ‐3% ‐4% ‐11%Billed un‐metered +/‐1% DI ‐3% ‐4% ‐11%Unbilled metered +/‐1% DI ‐3% ‐4% ‐11%Unbilled un‐metered +/‐1% DI ‐3% ‐4% ‐11%Unauthorised consumption +/‐2% 1% 0% 0%UARL +/‐10% *not relatively significant ‐10% ‐10% ‐10%Length of Mains +/‐2% 0% 0% 0%Number of connections +/‐2% 0% 0% 0%Average CSP length +/ 2% 0% 0% 0%Average CSP length +/‐2% 0% 0% 0%Average operating pressure +/‐2% 0% 0% 0%

Sensitivity Analysis – RankSensitivity Analysis – Rank Equivalence

476%500%

System input rank change sensitivity analysis

476%

300%

350%

400%

450%

500%

com

pani

es to

sw

ap ra

nk

20

25

30

99% 96% 95%83% 81% 71%

100% 99% 88%

52%100%

150%

200%

250%

age

chan

ge re

quire

d fo

r c

Volume parameters are the most sensitive

10

15

20

Perc

enta

ge C

hang

e

ILI Change

System Input

42%18%

52%46%26%32%

13%

0%

50%

Water Importe

dUnbille

d unmeteredUnbille

d metered

orised co

nsumption

Water Exp

orted

Length of mains

Service Pipe Length

Service Connectio

nsoperating pressu

reBille

d Metered

Billed Unmetered

r from own so

urces

Perc

enta

0

5

U

Unauthor S Se

Average op

Water

Parameter

Percent change required ST Percent change required UU

• Volume parameters probed the most sensitive using both rank methods

Water Company

• Volume parameters have the most confidence as they are derived from regulatory reported figures

Conclusions and FurtherConclusions and Further Research

• ILI can be readily calculated from reported data and is suitable for

icomparison purposes• ILI has limitations for targeting• Improvements are required in UARL

assumptions (AOP and CSP length)C i f th d l i• Comparison of the developing Economic Leakage Index (ELI) with frontier or relative efficiencyfrontier or relative efficiency approaches for economic levels of leakage is required