Non-Revenue Water Management

1. Non-Revenue Water Management Presented by Shankar Singh Engineer Public Utilities Commission (Guyana)

2. Why Non-revenue Water and not Unaccounted-for Water ?

3. Unaccounted-for Water • the difference between water produced and sold to the customers (through leaks, theft, etc.). Non-Revenue Water • water produced and “lost” before it reaches the customers (through leaks, theft, or legal usage for which no payment is made).

4. Difference between UfW and NRW Unaccounted-for Water UfW Non-Revenue Water NRW Customer Water Produced • Authorized usage without payment Water Lost • Leaks, theft, • etc. Customer Water Produced Water Lost • Authorized usage without payment • Leaks, theft, etc.

5. IWA/AWWA Standard Water Balance

6. 1. Unbilled Authorized Consumption • Water used for fire fighting. • Water for flushing distribution network. • In USA - low flow sprinklers on hydrants for cooling off during hot weather.

7. 2. Apparent Losses • Data handling errors – recording wrong unit. • Theft - Illegal service connections. - Meter by-pass. - Contractors taking illegal water supply for pressure testing.

8. 2. Apparent Losses (contd) • Metering inaccuracies: - wear from quality/quantity of water. - improper installation => turbulent flows - air in water => over-recording and damage. - under-recording at low flow. - improper meter size => oversized meters will under-record.

9. 3. Real Losses • Can often account for most of the NRW. • Mainly from leakages - T&D mains, service connections and other network components (eg. air valves) - Caused by aged pipelines and network components (defective air valves), pipe movement, heavy duty traffic, water conditions (pressure, pH).

10. Management of NRW • the lost water can be reduced. • amount recovered can then be used: - to meet current unsatisfied demand => increase revenue - to defer capital investment on additional supply => reduce capital cost - to reduce water production => reduce operational cost NRW Customer Water Produced Water Lost

11. Managing NRW A good strategy will include: • Leak detection and repair programme. => reduce real losses • Meter testing and replacement programme. => reduce apparent losses

12. Leak Detection & Repair Strategy 2 main methods for detecting leaks: • Listening Survey • Water Audit

13. Listening Survey • Involves sonic leak detection equipment to identify vibrations of the pipe (valve, hydrants, etc) as water escapes. • Correlator devices - listen at two points simultaneously to pinpoint the exact location of a leak.

14. Problems with Listening Surveys • Difficult to locate leaks in PVC pipes. • New backfilling material may sound like leak. • Large leaks make less noise. • Valves can sound like leaks. • Silent leaks - abandoned services - water crossings - leaks masked by highways and airport noise

15. Water Audit • Makes use of the IWA/AWWA Water Balance. • Distribution system is divided into DMAs. • Master meter should first be tested. • Flow measurements made over 24-hr periods. • Day and night flow comparisons can be made. • High night flow rates => good indication of a leak • Locate leak.

16. Typical DMA Pumping Station UfW 04/GT/03

17. Leak Repairs • Fixing leaks can be costly • Repair/replace? Replacement might last longer than repair. • Computation of cost of water lost by the leak vs. cost of repair/replacement may easily justify cost. • Eliminate risk of contamination

18. 2. Meter Test & Replacement Water Meters • “Cash registers” • Lose accuracy over time Meter Programme • Test production and large meters annually • Meter replacement programme • Meter properly sized

19. Guyana Size: 214,970 km2 Population: 751,223 (2002 census) Capital: Georgetown Exchange Rate ≈ GY$203 to US$1 Water Utility: Guyana Water Inc. Production Facilities: 117 Pipe Length ≈ 2,073 km №. of Customers ≈ 165,000 Min. Rural Domestic Rate: GY$60.90/m3 Georgetown Domestic Rate: GY$112/m3 NRW Target: 25 %

20. GWI West Bank Water Balance 2008

21. GWI Water Balance 2009

22. NRW and $$$ 2008 – NRW ≈ 69 % 2009 – NRW ≈ 32 % 2009 SIV: 109,197,895 m3 NRW Target @ 25% = 27,299,474 m3 NRW Volume: 34,380,158 m3 NRW exceeded target by 7,080,684 m3 (7%) At min. Domestic Rate of GY$60.91/m3 GY$431.3 M ≈ US$2.1 M

23. Conclusion Management of NRW can allow utilities to meet their regulatory requirements and to survive in competitive environments where such may exist.

24. Thank You

25. References • Unaccounted-for Water Puzzle: More Than Just Leakage, Paul V. Johnson - http://www.fwrj.com/articles/9602.pdf • Non-revenue water - http://en.wikipedia.org/wiki/Non-revenue_water • Leak Detection and Water Loss Control by Zacharia M. Lahlou, Ph.D. Civil and Environmental Engineer, Wiley and Wilson, Lynchburg, VA. http://www.nesc.wvu.edu/pdf/dw/publications/ontap/2009_tb/leak_detection_DWFSOM38.pdf • Unaccounted for Water “A Real Drain on Your Water System” http://www.mtas.tennessee.edu/knowledgebase.nsf/0/06c618903f5a75f28525726100586f56/$FILE/Unaccounted%20for%20Water.pdf • IWA/AWWA Water Audit Method http://www.awwa.org/Resources/WaterLossControl.cfm?ItemNumber=48055&navItemNumber=48162 • Water Loss Control Terms Defined http://www.awwa.org/Resources/WaterLossControl.cfm?ItemNumber=47866&showLogin=N • IBNET Indicators http://www.ib-net.org/en/ibnet-toolkit/ibnet-indicators/non-revenue-water.php?L=2&S=2&ss=3&PHPSESSID=b34f04f869d85aa47c0f4902e1bfcbc4 • Fire Hydrant http://en.wikipedia.org/wiki/Fire_hydrant • Assessing non-revenue water and its components – a practical approach. Water21 – August 2003, Allan Lambert, IWA Water Loss Task Force.