Addressing Non-Revenue Water

Transcription

1 Addressing Non-Revenue Water Smart Management for Small Water Systems

2 Addressing Non-Revenue Water Own Sources Water Imported Total Total System System Input Input (allow ( allow for for known known errors) errors ) Water Exported Water Supplied Authorized Authorized Consumption Consumption Water Water Losses Losses Billed Authorized Consumption Unbilled Authorized Consumption Apparent Losses Revenue Water Non- Revenue Water Billed Water Exported Billed Metered Consumption Billed Unmetered Consumption Unbilled Metered Consumption Unbilled Unmetered Consumption Unauthorized Consumption Customer Metering Inaccuracies Systematic Data Handling Error Leakage on Mains Real Losses Leakage on Service Lines Leakage & Overflows at Storage

3 Addressing Non-Revenue Water Water that is used by customers known to the water system but is not billed Water loss due to theft, slow meters and billing issues, also called commercial losses Water loss due to leakage in the system

4 How much non-revenue water is acceptable? Identify a goal or appropriate level of non-revenue water Facility and supply limits and economics will help you decide the level of action you should take In some states this is required California: < 10% unaccounted-for water Colorado: proposed reporting requirements for NRW water Ohio Public Utility Commission will not allow private utilities to charge customers for production of NRW in excess of 15% Some states now adopting the AWWA approach (GA, FL, TN)

5 Addressing Unbilled Authorized Consumption Billed Authorized Consumption Total System input Authorized Consumption Unbilled Authorized Consumption Water Losses Apparent Losses

6 Addressing Unbilled Authorized Consumption Water you don t bill for Fire fighting Flushing Public parks and golf courses Street cleaning Municipal facilities Other uses?? Unbilled Authorized Consumption

7 Addressing Unbilled Authorized Consumption Can your utility control Unbilled Authorized consumption more effectively? Unbilled Authorized Consumption Meter, estimate, report

8 Addressing Unbilled Authorized Consumption Meter Municipal Services Fountains Municipal Buildings Parks Conservation Meter, estimate, report Unbilled Authorized Consumption

9 Addressing Unbilled Authorized Consumption Flushing Filling mains compute volume Fire flow tests measure time and flow Flushing measure time and flow Keep records Meter Unbilled Authorized Consumption Meter, estimate, report

10 Addressing Unbilled Authorized Consumption Fire fighting Record number of events Estimate flows Meter? Unbilled Authorized Consumption Meter, estimate, report

11 Addressing Unbilled Authorized Consumption Improving Unbilled Unmetered Data Quality Estimate unbilled metered events Record number of unbilled events and develop a standard formula to calculate volume Conduct testing to look at actual vs. estimated flow Install meters Unbilled Authorized Consumption Start Here Work Towards Here

12 Addressing Unbilled Authorized Consumption Improving Unbilled Metered Data Quality Read meters on a regular basis Start meter testing program Develop systematic testing program Install automatic meter reading Test all meters annually Repair or replace all underperforming meters Continue Working Work Towards Here Unbilled Authorized Consumption

13 Addressing Apparent Losses Total System input Authorized Consumption Billed Authorized Consumption Unbilled Authorized Consumption Water Losses Apparent Losses

14 Addressing Apparent Losses Unauthorized consumption Customer meter inaccuracies Systematic data handling errors Apparent Losses

15 Addressing Apparent Losses Process is largely administrative No physical defect that allows water to be loss Apparent Losses

16 Addressing Apparent Losses Unauthorized Consumption Illegal taps Theft at hydrant Open bypasses Illegal use of fire services Apparent Losses Image from Maynilad Water Services Manila, Phillipines aynilad_water.shtml

17 Addressing Apparent Losses Unauthorized Consumption Estimate number of major incidents Evaluate types of incidents and number of occurrences of each Identify losses due to unauthorized consumption and aim to reduce Examine policy and procedures for gaps that allow for fraud Apparent Losses Start Here Work Towards Here

18 Addressing Apparent Losses Unauthorized Consumption Implement a monitoring and enforcement plan New regulations to target specific types of unauthorized consumption Review annually Continue Working Work Towards Here Apparent Losses

19 Addressing Apparent Losses Customer meter inaccuracies Apparent Losses Customer meter accuracy declines with age and varies between meter type and meter manufacturer Meter types Nutating Disc Oscillating Piston Turbine

20 How accurate are your customer meters? Accuracy depends on style and manufacturer Apparent Losses Data Courtesy Utah State University and Water Research Foundation

21 Addressing Apparent Losses Customer meter inaccuracies Target suspected problem areas due to meter age or type and test small number of meters Standardize meter testing over a larger area Replacement program for older meters Increase meter testing or replacement program over a wider area Apparent Losses Start Here Work Towards Here

22 Addressing Apparent Losses Systematic Data Handling Errors Errors that occur between when a meter is read and when a bill is sent to the customer Can be due to: Billing system entry errors Account adjustments Invalid meter consumption readings Meter rollover Meter change out Apparent Losses

23 Addressing Apparent Losses Systematic Data Handling Errors Conduct internal review of meter reading & billing systems Conduct internal checks on data vailidity and meter reading procedures Conduct annual internal checks of billing data Conduct third part audit with specific review for possible data handling and meter reading errors Apparent Losses Start Here Work Towards Here

24 Addressing Total System input Authorized Consumption Billed Authorized Consumption Unbilled Authorized Consumption Apparent Losses Water Losses Real Losses

25 Addressing Leakage Leakage on mains Leakage on service connections Leakage at finished water storage tanks including overflow events

26 Addressing Leakage Which leaks cause more water loss? Small hidden leaks Large surface leaks

27 Addressing Leakage Small hidden leaks can lead to most water loss Constant flow of low-level leaks causes more water loss than spectacular water main breaks 5-gpm leak running 100 days = 720,000 gallons 500-gpm leak running 4 hours = 120,000 gallons

28 Addressing Leakage Is the point you can see water the location of the leak? Yes or No?

29 Addressing Leakage Pinpointing a leak Water will take the path of least resistance Leaks don t always surface (especially the small constant or slowly increasing leaks) May surface far away from the leak Leaks may occur in places difficult to access (e.g., under a stream, highway or wetland) Pinpointing a leak saves money in repair costs

30 Addressing Ways to reduce leaks 1. Respond faster to known leaks 2. Asset Management 3. Reduce pressure 4. Find hidden leaks

31 Addressing Ways to reduce leaks 1. Respond faster to known leaks Water leak determination speed? Listen leaks cause vibration (sonic and subsonic noise) Pressure loss Staff availability Staff to respond to leaks Staff specialized in using necessary equipment Labor, equipment, and materials Stock repair parts Contractor contacts Team with other systems

32 Addressing Ways to reduce leaks 2. Asset Management Track main breaks to find weakest links Pipe inventory Pipe of particular size, age, and material that breaks in one location likely to break in other similar locations Oldest pipe is not necessarily the worst pipe Budget for timely replacement

33 Addressing Ways to reduce leaks 3. Reduce Pressure Reducing pressure reduces leak flow and the frequency of future water leaks Pressure can be reduced by altering pumps, installing new pressure reducing valves (PRVs), or changing existing PRVs New PRVs can reduce pressure when flow is reduced (nighttime) Photos courtesy Claval

34 Addressing Ways to reduce leaks 4. Find Hidden Leaks Leaks that do not surface Make some noise (sonic and subsonic) Can flood subsurface areas May cause cracks in paving or sinkholes May reduce pressure to customer Affect operations Pumps work harder Tanks harder to fill

35 Addressing Finding hidden leaks Technologies for detecting hidden leaks Active Listening Passive Listening Other detection technologies

36 Addressing Finding hidden leaks Characteristics of leak noise Impact of pipe size and type Small leaks higher frequencies Large leaks lower frequencies Smaller pipes > Larger pipes Metal Pipes > Cement or plastic pipes Transitions in pipe materials (clamps and couplings) muffle leak noise

37 Addressing Finding hidden leaks Characteristics of leak noise and separating from other noise Everyday vibrations (e.g., traffic, HVAC and electrical equipment) make listening difficult Continuous customer water use generates similar sound

38 Sonic ground listening devices Correlators Probes Walking main lines and listening at valves Issues Addressing Finding hidden leaks Active Technology Time and labor intensive Highly skilled staff or contractors Photo courtesy Texas Water Board

39 Permanent and semi-permanent listening devices Transmits data to central location Analyzes night flows Issues Still requires onsite visit to investigate possible leaks Cost Addressing Finding hidden leaks Passive Technology

40 Addressing Finding hidden leaks Additional Technologies Tracer Gas Leak Detection Sahara, Smartball Issues Works best for a pipe that is out of service Complex and expensive

41 Addressing Finding hidden leaks Additional Technologies GPR and infrared sensors Devices can be inserted into pipe to locate leaks and the pipe itself Issues Not suitable in certain regions Complex and expensive Ground penetrating radar Insertion camera

42 Addressing Finding hidden leaks What should you have in your toolbox? Listening stick to monitor services, hydrants

43 Addressing Finding hidden leaks What should you have in your toolbox? A ground microphone that filters and amplifies sound

44 Addressing Finding hidden leaks What should you have in your toolbox? Budget permitting, a leak noise correlator especially if leaks do not surface readily

45 Addressing Finding hidden leaks What should you have in your toolbox? Overnight correlators and programmable monitors only recommended when justified economically (factors include high cost of water, chronic leakage, noisy locations)

46 Addressing Leak detection strategies

47 Addressing Leak detection strategies Leak detection survey Make contact with elements in system (hydrants, valves, curb stops) and listening for acoustic signatures of leaks Done on a periodic basis with frequency dependent on the system Increase frequency in leak-prone areas

48 Addressing Leak detection strategies Manned nighttime surveys Nighttime listening operation implemented to reduce real water use, noise, traffic Nighttime listening operation makes program costlier and dangerous to surveyor Finding sufficient number of contact points can be challenging in dark

49 Addressing Leak detection strategies Leak survey issues: Internal vs. external There are capable consultants but results and satisfaction may vary. Internal operation justified when leaks are frequent and staff is used at different intervals to pinpoint leaks

50 Addressing Leak detection strategies District metering Allows for better accounting of leak flow and finding hidden bursts Breaking the system into small isolated zones and monitor flow at minimum flow time (3 a.m.) When a zone has high minimum flow, surveys can be targeted and step testing can be used DMA zones lend themselves to better PRVs and lowered leakage Graphic courtesy of Thames Water

51 Addressing Addressing reported leaks Start reporting leaks and breaks Repair leaks more quickly Develop standards to find, repair and document leaks and breaks Standardize record keeping for leak location and repair data Implement computerized maintenance management system Look at failure trends Start Here Work Towards Here

52 Addressing Addressing unreported leaks Plan, Implement and Improve a proactive leak detection program coupled with asset management

53 Address real losses by focusing on leakage types and the tools to control them Unavoidable Detectable Observable Proactive leak detection and repair Improve speed of repair

54 Addressing Discussion What approaches do you use? Is there another approach that might work better for you? What experience have you had with leak surveys?

55 Addressing Non-Revenue Water Summary Start by getting an estimate of your nonrevenue water Then see if you can estimate areas of authorized unbilled and other losses Work to minimize different categories of loss it may vary within your system

56 What type of non-revenue water? 1. Leak on a water main 2. City parks department 3. Fire department use 4. Inaccurate customer meter 5. Theft from a hydrant 6. Unauthorized tap 7. Service line leak 8. Leak in customer s plumbing (after meter) Unbilled authorized consumption Apparent losses Real losses

57 Identify where water loss could be occurring. Define as unbilled authorized, apparent, or real loss. What would you do to reduce water loss? Treatment Plant