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

2. Firstly, how do we define Non-Revenue Water?
Let’s look at the IWA Standard Water Balance

3. The Danger of Relying on Percentages
Paradise Island

4. The Danger of Relying on Percentages
Paradise Island
At Normal Demand NRW = 30%

5. The Danger of Relying on Percentages
Paradise Island
With Increased Demand NRW = 25%

6. The Danger of Relying on Percentages
Paradise Island
With Reduced Demand NRW = 37.5%

7. The Danger of Relying on Percentages
NRW 30 %
NRW 25 %
NRW 37.5 %
But NRW Volume (including
Real Losses) are Unchanged
Don’t be fooled – Be aware
Paradise Island

8. The Danger of Relying on Percentages
NRW 30 %
NRW 25 %
NRW 37.5 %
Paradise Island
Best Performance Indicators for Real Losses
Litres/conn/day (urban areas) or
m3/km main/day (rural areas), and
Infrastructure Leakage Index (ILI)

9. Developing a NRW Strategy
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

10. Developing a NRW Strategy
Key Objective #1 Continued
Reliably measure System Input Volume
Is a suitably sized meter installed?
Is it installed correctly?
Is ‘air’ an issue?
Is data being accurately recorded?

11. Developing a NRW Strategy
Key Objective #2
Maximise Revenue Water
Are meters installed at the property boundary?
Are meters recording water use accurately?
Are water bills correct?

12. Developing a NRW Strategy
Key Objective #2 Continued
Maximise Revenue Water
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?

13. Developing a NRW Strategy
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?

14. Developing a NRW Strategy
Key Objective #3 Continued
Minimise Apparent Losses
Customer Meter Under-registration – Check meter accuracy – use a 20 litre container? In-line meter calibration check? Bench tests?

15. Developing a NRW Strategy
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)

16. Developing a NRW Strategy
Key Objective #4 Cont’d
Reduce Real Losses
The Four Complementary
Leakage Management Activities

17. Developing a NRW Strategy
Key Objective #4 Cont’d
Reduce Real Losses
1. Speed and quality of repairs

18. Leak Run Time Awareness
Leak Volume Loss = (A+ L+R ) Time x Flow Rate
LEAK RUN TIME
FLOW RATE A L R
RUN TIME
= *Awareness + Location + Repair

19. Bursts with high flow rates don’t produce the largest volumes of Real Losses! Run time is a key factor.
m3 / day 75
reported mains burst
82.5 m3
1.1 Days
m3 / day
16 Days
reported service connection burst
400 m3 25 R L A
In the past, we spent a lot of time locating burst mains and feeling satisfied when they were repaired.
Recent research has shown (in the top diagram) that whilst the average burst main runs at 75m3/day, it is repaired after only 1.1days, losing 82.5m3 in total.
The Water Supplier’s communication pipe has a lower flow rate at 25m3/day but runs for 16 days losing 400m3 .
Worst of all is the leak inside the customers boundary which loses 1150m3, 14 times more than the average burst main. It is therefore very important that the leakage practitioner understands the condition of his distribution system and where the leaks might occur. L
m3 / day
unreported service
connection burst
> 4500 m3 25
6 months? R A 19

20. It’s OK. It’s been
like that for weeks.
THIS RESULTS IN VERY HIGH WATER LOSS

21. I’ll ring or text the
water people so it
will be fixed straight
away.
THIS IS THE PATH TO LOW WATER LOSSES

22. The volume leaked:
Say 7 litres/min x 60 x 24 = 10,080 litres/day,
= 10m3/day
= 70m3/week
= 3,680m3/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 cost (at NZ$.40/m3) = $4/day
= $28/week,
= $1,450/year

23. I think a Public Relations Plan
may be required as part of a NRW Strategy so that the public report faults straight away –
And it will be important that the utility follow up by:
Fixing leaks promptly &
Fixing leaks properly

24. Developing a NRW Strategy
Key Objective #4 Cont’d
Reduce Real Losses
2. Pipe materials management, selection, installation, maintenance, renewal

25. Take Note: Leakage from watermains is generally not the key issue, leakage from service connections is

26. Developing a NRW Strategy
Key Objective #4 Cont’d
Reduce Real Losses
3. Active Leakage Control

27. Active Leakage Control
Active Leakage Control (ALC) is the only way to locate ‘Unreported’ leaks.

28. Active Leakage Control

29. Sectorizing a Water Supply Network

30. Monitoring of Minimum Night Flows into a Network or Zone
Monitor Low Flows at Night

31. Developing a NRW Strategy
Key Objective #4 Cont’d
Reduce Real Losses
4. Pressure Management

32. Relationship Between System Pressure & Losses
N1 varies depending mainly on
pipe material & existing leakage rates

33. Example of Pressure Management Reducing Real Losses (and Demand)
Water pressure reduced by 30%
33% Reduction in Minimum Night Flowrate

34. Flow and Pressure Control Installation

35. Developing a NRW Strategy – To Recap
Key Objective #1
Reliably measure System Input Volume
Key Objective #2
Maximise Revenue Water

36. Developing a NRW Strategy – To Recap
Key Objective #3
Minimise Apparent Losses (Unauthorised consumption and Customer Meter Under- registration)

37. Developing a NRW Strategy – To Recap
Key Objective # Reduce Real Losses

38. Why Reduce Non-Revenue Water?
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.)
Other good reasons….

39. Why Reduce Non-Revenue Water?
HAPPY CUSTOMERS
HAPPY WATER ENGINEERS
HAPPY WATER BOSSES

40. Thank you
Any questions?