Addressing Non-Revenue Water
Smart Management for Small Water Systems
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Addressing Non-Revenue Water
Water
Imported
Own
Sources
Total
System
Input
( allow
for
known
errors )
Total
System
Input
(allow
for
known
errors)
Water
Supplied
Water
Exported
Water
Supplied
Water
Exported
Water
Losses
Authorized
Consumption
Water
Imported
Own
Sources
Total
System
Input
( allow
for
known
errors )
Water
Imported
Own
Sources
Total
System
Input
( allow
for
known
errors )
Total
System
Input
(allow
for
known
errors)
Water
Supplied
Water
Exported
Water
Supplied
Water
Exported
Water
Losses
Authorized
Consumption
Water
Losses
Authorized
Consumption
Real
Losses
Apparent
Losses
Unbilled
Authorized
Consumption
Billed
Authorized
Consumption
Non-
Revenue
Water
Revenue
Water
Leakage & Overflows at Storage
Billed Unmetered Consumption
Billed Metered Consumption
Billed Water Exported
Leakage on Service Lines
Leakage on Mains
Customer Metering Inaccuracies
Unauthorized Consumption
Unbilled Unmetered Consumption
Unbilled Metered Consumption
Systematic Data Handling Error
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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
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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)
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Water Losses
Authorized ConsumptionTotal
Systeminput
Real Losses
Apparent Losses
Billed Authorized Consumption
Unbilled Authorized Consumption
Addressing Unbilled
Authorized Consumption
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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
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Can your utility control Unbilled Authorized
consumption more effectively?
Addressing Unbilled
Authorized Consumption
Meter, estimate, report
Unbilled Authorized Consumption
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• Meter Municipal Services Fountains
Municipal Buildings
Parks
• Conservation
Unbilled Authorized Consumption
Addressing Unbilled Authorized Consumption
Meter, estimate, report
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• Flushing Filling mains – compute volume
Fire flow tests – measure time and flow
Flushing – measure time and flow
Keep records
Meter
Addressing Unbilled Authorized Consumption
Unbilled Authorized Consumption
Meter, estimate, report
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• Fire fighting
Record number of events
Estimate flows
Meter?
Meter, estimate, report
Addressing Unbilled Authorized Consumption
Unbilled Authorized Consumption
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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 metersUnbilled Authorized Consumption
Start Here
Work Towards
Here
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Addressing Unbilled Authorized Consumption
• 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
Unbilled Authorized Consumption
Improving Unbilled Metered Data Quality
Continue Working
Work Towards
Here
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Addressing Apparent Losses
Water Losses
Authorized ConsumptionTotal
Systeminput
Real Losses
Apparent Losses
Billed Authorized Consumption
Unbilled Authorized Consumption
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• Unauthorized consumption
• Customer meter inaccuracies
• Systematic data handling errors
Apparent Losses
Addressing Apparent Losses
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• Process is largely administrative
• No physical defect that allows water
to be loss
Apparent Losses
Addressing Apparent Losses
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Unauthorized Consumption
• Illegal taps
• Theft at hydrant
• Open bypasses
• Illegal use of fire
services
Apparent Losses
Addressing Apparent Losses
Image from Maynilad Water Services – Manila, Phillipineshttp://www.puretechltd.com/case_studies/water_pipeline/maynilad_water.shtml
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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 fraudApparent Losses
Addressing Apparent Losses
Start Here
Work Towards
Here
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Unauthorized Consumption
• Implement a monitoring and
enforcement plan
• New regulations to target specific
types of unauthorized consumption
• Review annually
Apparent Losses
Addressing Apparent Losses
Continue Working
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Here
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Customer meter inaccuracies
• Customer meter accuracy declines with age
and varies between meter type and meter
manufacturer
• Meter types
Nutating Disc
Oscillating Piston
Turbine
Apparent Losses
Addressing Apparent Losses
www.smartmeasurement.com
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How accurate are your
customer meters?
• Accuracy depends on style and
manufacturer
Data Courtesy Utah State University and Water Research Foundation
Apparent Losses
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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
Addressing Apparent Losses
Start Here
Work Towards
Here
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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
Addressing Apparent Losses
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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 errorsApparent Losses
Addressing Apparent Losses
Start Here
Work Towards
Here
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Addressing Real Losses
Water Losses
Authorized Consumption
TotalSysteminput
Real Losses
Apparent Losses
Billed Authorized Consumption
Unbilled Authorized Consumption
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Real Losses
Addressing Real LossesLeakage
• Leakage on mains
• Leakage on service connections
• Leakage at finished water storage tanks
including overflow events
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Real Losses
Addressing Real Losses
Which leaks cause more water loss?
Small hidden leaks Large surface leaks
Leakage
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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
Real Losses
Addressing Real LossesLeakage
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Real Losses
Addressing Real Losses
Is the point you can see water the location of the leak?
Yes or No?
Leakage
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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
Real Losses
Addressing Real LossesLeakage
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1. Respond faster to known leaks
2. Asset Management
3. Reduce pressure
4. Find hidden leaks
Addressing Real LossesWays to reduce leaks
Real Losses
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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
Addressing Real LossesWays to reduce leaks
Real Losses
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• 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
2. Asset Management
Addressing Real LossesWays to reduce leaks
Real Losses
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• 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
Real Losses3. Reduce Pressure
Addressing Real LossesWays to reduce leaks
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• 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
4. Find Hidden Leaks
Addressing Real LossesWays to reduce leaks
Real Losses
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Technologies for detecting hidden leaks
• Active Listening
• Passive Listening
• Other detection
technologies
Addressing Real LossesFinding hidden leaks
Real Losses
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Characteristics of leak noiseImpact 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
Addressing Real LossesFinding hidden leaks
Real Losses
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• Everyday vibrations (e.g., traffic, HVAC
and electrical equipment) make listening
difficult
• Continuous customer water use
generates similar sound
Characteristics of leak noiseand separating from other noise
Addressing Real LossesFinding hidden leaks
Real Losses
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• Sonic ground listening devices
• Correlators
• Probes
• Walking main lines and listening at valves
Issues
• Time and labor intensive
• Highly skilled staff or contractors
Photo courtesy Texas Water Board
www.fujitecom.com
Active Technology
Addressing Real LossesFinding hidden leaks
Real Losses
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• Permanent and semi-permanent listening
devices
• Transmits data to central location
• Analyzes night flows
Issues
• Still requires onsite visit to investigate
possible leaks
• Cost
Passive Technology
Addressing Real LossesFinding hidden leaks
Real Losses
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• Tracer Gas Leak Detection
• Sahara, Smartball
Issues
• Works best for a pipe that is out of
service
• Complex and expensive
Additional Technologies
Addressing Real LossesFinding hidden leaks
Real Losses
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• 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
Additional Technologies
Addressing Real LossesFinding hidden leaks
Real Losses
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Listening stick to
monitor services,
hydrants
What should you have in your toolbox?
Addressing Real LossesFinding hidden leaks
Real Losses
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A ground microphone
that filters and
amplifies sound
What should you have in your toolbox?
Addressing Real LossesFinding hidden leaks
Real Losses
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Budget permitting, a leak noise correlatorespecially if leaks do not surface readily
What should you have in your toolbox?
Addressing Real LossesFinding hidden leaks
Real Losses
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Overnight correlatorsand programmable monitors only recommended when justified economically (factors include high cost of water, chronic leakage, noisy locations)
What should you have in your toolbox?
Addressing Real LossesFinding hidden leaks
Real Losses
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Leak detection strategies
Addressing Real Losses
Real Losses
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• 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
Leak detection survey
Addressing Real LossesLeak detection strategies
Real Losses
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• 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
Real Losses
Manned nighttime surveys
Addressing Real LossesLeak detection strategies
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• 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
Leak survey issues: Internal vs. external
Addressing Real LossesLeak detection strategies
Real Losses
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• 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
District metering
Addressing Real LossesLeak detection strategies
Real Losses
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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
Addressing Real Losses
Real Losses
Start Here
Work Towards
Here
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Addressing unreported leaks
Plan, Implement and Improve
a proactive leak detection program
coupled with asset management
Addressing Real Losses
Real Losses
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Address real losses by focusing on leakage
types and the tools to control themUnavoidable Detectable Observable
• Proactive leak detection and repair
• Improve speed of repair
Real Losses
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• What approaches do you use?
• Is there another approach that might work
better for you?
• What experience have you had with leak
surveys?
Addressing Real LossesDiscussion
Real Losses
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• Start by getting an estimate of your non-
revenue 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
Addressing Non-Revenue WaterSummary
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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
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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