Richard Taylor, Thomas Civil & Environmental Consultants h PWC’15 September 2015 Developing a Non- Revenue Water Strategy

Richard Taylor, Thomas Civil & Environmental Consultants

h

PWC’15 September 2015

Developing a Non- Revenue Water Strategy

Let’s look at the IWA Standard Water Balance

Firstly, how do we define Non-Revenue Water?

The Danger of Relying on Percentages

Paradise Island


27 m3

Real Losses30 m3

Unbilled Authorised Consumption% NRW =

30m3/100m3 = 30%

Apparent Losses Non-Revenue Water

Water Supplied

100 m3

System Input Billed Consumption Revenue Water

or 70 m3 70 m3

Paradise Island

At Normal Demand NRW = 30%


27 m3

Real Losses30 m3


30m3/120m3 = 25%


Water Supplied

120 m3


or 90 m3 90 m3

INCREASED

Paradise Island

With Increased Demand NRW = 25%


27 m3

Real Losses30 m3


30m3/80m3 = 37.5%


Water Supplied

80 m3


or 50 m3 50 m3

DECREASED

Paradise Island

With Reduced Demand NRW = 37.5%


Paradise Island

27 m3

Real Losses30 m3

Unbilled Authorised ConsumptionApparent Losses Non-Revenue

Water

Water Supplied

120 m3


or 90 m3 90 m3

INCREASED

27 m3

Real Losses30 m3


Water

Water Supplied

100 m3


or 70 m3 70 m3

NRW 30 % NRW 25 % NRW 37.5 %

But NRW Volume (including

Real Losses) are Unchanged

Don’t be fooled – Be aware

27 m3

Real Losses30 m3


Water

Water Supplied

80 m3


or 50 m3 50 m3

DECREASED

Best Performance Indicators for Real Losses

Litres/conn/day (urban areas) or

m3/km main/day (rural areas), and

Infrastructure Leakage Index (ILI)


Paradise Island NRW 30 % NRW 25 % NRW 37.5 %

27 m3

Real Losses30 m3


Water

Water Supplied

120 m3


or 90 m3 90 m3

INCREASED

27 m3

Real Losses30 m3


Water

Water Supplied

100 m3


or 70 m3 70 m3

27 m3

Real Losses30 m3


Water

Water Supplied

80 m3


or 50 m3 50 m3

DECREASED

Where do we start?

Key Objective #1

Reliably measure System Input Volume

•It is essential that the volume of water supplied into the water network is reliably measured

Developing a NRW Strategy

Key Objective #1 Continued


•Is a suitably sized meter installed?

•Is it installed correctly?

•Is ‘air’ an issue?

•Is data being accurately recorded?


Key Objective #2

Maximise Revenue Water

•Are meters installed at the property boundary?

•Are meters recording water use accurately?

•Are water bills correct?




•Have a plan to meter any ‘unmetered’ connections

•Is all water utility and public water use metered and billed? Parks, toilets etc.

•Is water tanker use metered and billed?


Key Objective #3

Minimise Apparent Losses

•Unauthorised Consumption - Have a plan to check for illegal connections. Reward meter readers? Compare aerial photos with meter locations (desktop study)? Door to door check?



Minimise Apparent Losses

•Customer Meter Under-registration – Check meter accuracy – use a 20 litre container? In-line meter calibration check? Bench tests?


Key Objective #4

Reduce Real Losses

These include:

•Leakage on mains

•Leakage and overflows at reservoirs

•Leakage on service connections up to the street/property boundary (meter location)


Key Objective #4 Cont’d

Reduce Real Losses


The Four ComplementaryLeakage Management Activities


Reduce Real Losses


1. Speed and quality of repairs

Leak Run Time Awareness

A L R

LEAK RUN TIME

FL

OW

RA

TE

RUN TIME

Leak Volume Loss = (A+ L+R ) Time x Flow Rate

= *Awareness + Location + Repair

m3

/ day

75

reported mains burst

82.5 m3

1.1 Days

Lm3

/ day

unreported serviceconnection burst

> 4500 m3256 months?

RA

m3

/ day 16 Days

reported service connection burst

400 m325

RLA

Bursts with high flow rates don’t produce the largest

volumes of Real Losses! Run time is a key factor.

It’s OK. It’s been like that for weeks.

THIS RESULTS IN VERY HIGH WATER LOSS

I’ll ring or text the water people so it will be fixed straight away.

THIS IS THE PATH TO LOW WATER LOSSES

The cost (at NZ$.40/m3) = $4/day= $28/week, = $1,450/year

The leak has to be repaired some time. Delaying doesn’t save any money, it costs money and causes high leakage (and high NRW)

The volume leaked:Say 7 litres/min x 60 x 24 = 10,080 litres/day,= 10m3/day= 70m3/week = 3,680m3/year

And it will be important that the utility follow up by:

•Fixing leaks promptly &

•Fixing leaks properly

I think a Public Relations Planmay be required as part of a NRW Strategy so that the public report faults straight away –


Reduce Real Losses


2. Pipe materials management, selection, installation, maintenance, renewal

Take Note: Leakage from watermains is generally not the key issue, leakage

from service connections is

Infrastructure ComponentBackground

LeakageReported Bursts Unreported Bursts Total

Mains 19.5% 9.3% 1.9% 30.7%

Service Connections 57.0% 11.0% 1.2% 69.3%

Totals 76.5% 20.3% 3.2% 100.0%


Reduce Real Losses


3. Active Leakage Control

Active Leakage ControlActive Leakage Control (ALC) is the only way to locate ‘Unreported’

leaks.

Active Leakage Control

Sectorizing a Water Supply Network

Monitoring of Minimum Night Flows into a Network or Zone

0

20

40

60

80

100

120

0 6 12 18 24 30 36 42 48

Hours

Hyd

rau

lic

Gra

de

Lin

e (H

GL

)

(m)

0

20

40

60

80

100

120

Flo

w

(l/s

)

112 m

91 m

Q Min = 10.9 l/s Q Min = 7.3 l/s

Monitor Low Flows at Night


Reduce Real Losses


4. Pressure Management

Relationship Between System Pressure & LossesN1 varies 0.5 - 2.5 depending mainly on

pipe material & existing leakage rates

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 1.10 1.20

Ratio of Pressures P1/Po

Rati

o o

f L

eakag

e R

ate

s L 1/

Lo

N1 = 0.50

N1 = 1.00

N1 = 1.15

N1 = 1.50

N1 = 2.50

Example of Pressure Management Reducing Real Losses (and Demand)

0

20

40

60

80

100

120

0 6 12 18 24 30 36 42 48

Hours

Hyd

rau

lic

Gra

de

Lin

e (H

GL

)

(m)

0

20

40

60

80

100

120

Flo

w

(l/s

)

112 m

91 m

Q Min = 10.9 l/s Q Min = 7.3 l/s

Water pressure reduced by 30%

33% Reduction in Minimum Night Flowrate

Flow and Pressure Control Installation

Key Objective #1


Developing a NRW Strategy – To Recap

Key Objective #2


Key Objective #3

Minimise Apparent Losses (Unauthorised consumption and Customer Meter Under-registration)


Key Objective #4 Reduce Real Losses


Water Scarcity Ex Harrison Mutikanga - AFRICA

•Absolute scarcity (insufficient quantity at the source – exacerbated by climate change)

•Economic scarcity (financial constraints to expand infrastructure to meet increasing demand; poor planning & demand forecasting)

•Scarcity from poor management (high leakage & wastage, poor O & M practices, governance issues – corruption, etc.)

Why Reduce Non-Revenue Water?

Other good reasons….

HAPPY CUSTOMERS

HAPPY WATER ENGINEERS

HAPPY WATER BOSSES

Why Reduce Non-Revenue Water?

Thank you

Any questions?

Documents

Richard Taylor, Thomas Civil & Environmental Consultants h PWC’15 September 2015 Developing a Non- Revenue Water Strategy