Water Loss Control - What Can Be Done?

Water utilities can control losses in their operations by compiling an annual water audit of their supply operations, and by implementing programs to identify and contain inefficiencies.  Such programs include leakage management, meter accuracy testing and enforcement against unauthorized consumption of water.

Losses in water utility operations occur in two distinctly different manners.  Apparent losses occur due to customer meter inaccuracies, billing system data errors and unauthorized consumption.  These losses cost utilities revenue and distort data on customer consumption patterns.  Losses also occur as Real losses or water that escapes the water distribution system, including leakage and storage overflows.  These losses inflate the water utility’s production costs and stress water resources since they represent water that is extracted and treated, yet never reaches beneficial use.

Specific interventions exist to combat both apparent and real losses.  It is important that the water utility determine the cost impact to the water utility from its apparent and real losses, and design an intervention strategy that takes into account the water resources and economic benefits of containing these losses.

Controlling Apparent Losses 

Three sub-categories of apparent losses have been defined as given below: 

Customer Meter Inaccuracy

The majority of North American water utilities provide their customers with water meters to measure consumption.  Most meters retain accuracy over long periods of continuous use, but many types of meters can lose accuracy quickly once they reach a threshold level of high cumulative consumption.  This level varies among the various meter models.  Inaccurate meters tend to under-register consumption volumes, thereby a loss is incurred.  Water utilities should closely monitor customer consumption trends to identify meters that have lost accuracy.  Meter accuracy testing should be conducted on an ongoing basis to stay on top of the disposition of the meter population.  Usually a sample of the meter population is tested regularly.

Systematic Data Handling Errors

Systematic Data Handling Error includes errors in the meter reading, billing and data archival paths of the water utility.  A water utility may have accurate customer meters, but unless the integrity of the consumption measure is ensured throughout the entire path, then errors can appear on customer bills or management reports.  Often such errors lead to afire hydrant flushn under-statement of actual consumption volumes.  Such errors distort assessments of customer consumption (compromising water conservation assessments) and cost utilities revenue.  Water utilities should assess these practices to determine if inefficiencies exist such as poor meter reading results from access limitations to meters or human error in transposing meter readings manually.  Billing policies and procedures should also be reviewed.  Do policies allow some customers to go unmetered or unbilled?  Do all customers exist with an account in the customer billing system (whether or not the system is metered)?  Flowcharting the billing system process is a relatively quick way to uncover possible gaps in procedure or policy that allow groups of customers to go unmetered or unbilled.  Often municipally-owned buildings are unmetered and unbilled, usually on the basis that they do not generate revenue for municipally-owned water utilities.  However, left unmonitored, these buildings often waste water due to plumbing leaks or wasteful practices and the loss water goes undetected.  Water utilities can often find significant uncaptured revenue that can be recouped once an evaluation of the billing information handling process is undertaken

Unauthorized Consumption 

Unauthorized Consumption can occur in many manners as there are always unscrupulous persons who contrive ways to avoid paying for service.  Water utilities should have clearly defined policies and regulations for water service provision, and means to detect common breaches in the supply, metering and billing processes.  Utilities should likewise have policies for customers who encounter a true inability to pay for water service.  Unauthorized consumption results in wasted water resources and billings lost by the water utility.  This often results in additional cost being passed along to the paying customer population.

Drinking water is a critical service for communities but this service must generate revenue for water utilities to meet their cost of service in maintaining the water infrastructure.  Adequate revenue capture relies upon efficient systems of customer metering, meter reading, billing and enforcement that prevent consumption data error – and revenue loss – from occurring.   For most water utilities the customer billing system also becomes the de facto customer consumption database, and many functions rely upon the integrity of the customer consumption data that is included here.  When consumption data integrity is corrupted by such errors, the effects of water conservation programs might not be accurately assessed.  Similarly, demand data for water distribution system hydraulic modeling or planning studies may be corrupted.  Water utilities have many persuasive reasons to assess and contain apparent losses in their operations.

Controlling Real Losses

Many drinking water utilities around the world respond to leaks only after they have received a report of water erupting from a street or a complaint from a customer about a damp basement, or other visible sign of leakage.  Utilities that employ this type of reactive leakage response most likely have excessive leakage that will never be effectively contained.  Controlling leakage effectively relies upon a proactive leakage management program that includes a means to identify hidden leaks, optimize repair functions and upgrade piping infrastructure as its useful life ends.  The science of leakage management has evolved rapidly, and is moving from a singular “find and fix” approach to a more comprehensive “predict and prevent” strategy.  The current approaches include four prongs of attack:

Active Leakage Control

pipe leak 3Seeking hidden, or unreported leaks, by sonically canvassing the water distribution system (leak detection survey) or using automated leak noise monitoring or minimum hour flow analysis to detect newly emerging leaks as they occur. 

Speedy, quality repairs – Once a leak or rupture is known, water utilities must be able to respond quickly to effect quality, lasting repairs.  Repair policies also play a role here, typically regarding leaks on customer service connection piping.  Many water utilities require that their customers arrange for repairs on their leaking service piping.  This policy often results in delays in getting known leaks repaired.  Alternative approaches such a warranty or insurance programs for customer service lines can be more effective in ensuring timely leak repairs.

Pressure Management

Intuitively it is easily understood that water escapes faster from a leak at a relatively high pressurepressure reducing valve 1 than water leaking at relatively low pressure.  Yet most water utilities do not take into consideration the effects of excessive pressure levels that may exist in parts of their water distribution systems.  Pressure management is one of the more recent, and highly effective, means to control excessive leakage losses.  It is particularly effective for systems that suffer high levels of background leakage, which is the collective leakage from many weeps and seeps at pipe joints and fittings.  Reducing pressures at low demand hours has been found to be very cost-effective in reducing background leakage.  Pressures into discrete pressure zones or District Metered Areas (DMA) can be controlled by pressure reducing valves (PRV) that regulate water supply pressure into the zone.

Water Main Rehabilitation and Replacement

All pipeline assets eventually reach the end of their service life and must be rehabilitated or replaced.  Water utilities should have in place funding and programs to identify expiring assets and ensure that they are reconditioned to continue to provide reliable service.

Leakage Component Analysis

By using data collected by a water utility on the number and types of leaks found and repaired in their water distribution system, a Leakage Component Analysis can be conducted to help utilities determine the extent of leakage control activities that are economic to undertake.  This method segregates water system failure events into Reported leaks and breaks (visible leakage), Unreported leaks (hidden leaks), and Background Leakage (hidden weeps and seeps that are acoustically undetectable but responsive to pressure management).  For each of these three categories of leakage, three time periods in the life of the leak are approximated.  These are the Awareness period (leak emergence until the utility becomes aware of the leak), the Location period (time needed to pinpoint the leak source), and the Repair period (time to halt the flow of water leakage).  A primary goal of the leakage control strategy is to limit the duration in which leaks run, since annual leakage losses are aggravated by long leakage durations more than the magnitude of the leaks.  By setting an objective to contain the Awareness, Location, and Repair times, water losses from a leak can be minimized.  Every each water utility encounters a unique production cost for their water supply, and unique labor and equipment costs for leakage control.  The component analysis takes these system-specific costs into account when determining the range of leakage control activities that are most suited economically for the utility to undertake.

Fortunately a free tool exists for water utilities to employ to conduct a leakage component analysis.  The Water Research Foundation and the United States Environmental Protection Agency sponsored the research project Real Loss Component Analysis: a Tool for Economic Water Loss Control.  The project produced a spreadsheet software tool that provides users with an easy format to enter data on the leakage events that occur in a water utility over the course of a year.  Utilizing various data from the standard water audit, the tool calculates the economically optimum leakage levels and relates the appropriate leakage control activities such as acoustic leak detection and pressure management to reduce leakage in the water distribution system.  The tool may be downloaded for free from: http://www.waterrf.org/Pages/Projects.aspx?PID=4372

Tools and Guidance for Small and Rural Water Utilities

The Water Research Foundation sponsored a project entitled Pipe Location and Leakage Management for Small Water Utilities (Project #4144) which created technical guidance modules to assist small systems operators in locating their buried infrastructure, identify water loss sources, and locate leaks. The primary output of the project is a series of presentation materials suitable for a workshop setting. A written report supplements the presentation material, and outlines project issues as well as being a reference for other materials to be used by small system operators and trainers. Many of the recommendations in the presentation are also applicable to larger systems. Most leak detection devices of use to small systems fall into the following categories: listening rods, ground microphones, correlators, noise loggers and pipe intrusive acoustics.

The project also highlights effective methods for tracing and locating buried piping that is not well documented on maps. In order to maintain pipe, valves, connections and service lines, all water system operators need to know their physical location and condition, particularly if they are beginning to fail. The inevitable deterioration of the underground pipe network requires increasing awareness of piping and valve locations to limit damage in addition to having the ability to identify when and where failures are occurring.  The materials developed during this research work give water utilities of all sizes the capabilities that they need to address excessive leakage in their water distribution systems.  Information on this project can be found at: http://www.waterrf.org/Pages/Projects.aspx?PID=4144

In addition to the leak detection equipment mentioned above, more sophisticated leak detection and pipeline condition assessment methods continue to be introduced to the water industry.  Some of these include fiber-optic cable placed inside the pipe to hear sound or placed outside the pipe (during installation) to detect changes in temperature between the leaking water and the soil temperature. Another non-acoustic method is hydrogen or helium gas injected into pipeline and used as a tracer gas to locate leaks in pipelines. The costs of these methods can be more expensive than traditional acoustic leak detection and beyond the practical everyday use by smaller systems. Technologies are continuously advancing and water utilities should stay abreast of these developments and consider applying them to the extent that they are practical and economic.

An array of effective leakage control equipment and technologies exist to provide water utilities with the tools to combat leakage and manage real losses to economically low levels.  However, it is incumbent upon each water utility to be proactive in implementing a leakage management program.  Merely responding to reported leaks and breaks when they surface means that the water utility is not in control of its leakage, which will inevitably continue to rise over time.

Getting Started

Compiling a water audit – even one based on preliminary data – is the best way to get started.  Along with quantifying volumes of apparent and real losses, make sure that you assess the cost impact that these losses are exerting on the water utility operations.  Once the costs of losses are known, justifications can be made to launch the efforts that will recoup these costs.

Water Loss Control References

A number of timely publications and research reports are available that explain the best practice approaches to water loss control:

Water Audits and Loss Control Programs, AWWA M36 Guidance manual 4th Edition, 2016  This is the industry leading best practice guidance publication which provides comprehensive instructions on the compilation of the AWWA/IWA Water Audit as well as state-of-the-art methods to control apparent and real losses. http://www.awwa.org/store/productdetail.aspx?productid=51439782.

Water Loss Control, 2nd Edition, 2008  This comprehensive text provides information on the AWWA/IWA Water Audit Methodology and state-of-the-art methods to control apparent and real losses.  It offers a large array of case study accounts that detail how water utilities from around the world are achieving dramatic reductions in water and revenue loss. Click here to go to the AWE on-line publication order form. 

Research Report for Project 2811:  Evaluating Water Loss and Planning Loss Reduction Strategies, Water Research Foundation, 2007.  This work assessed the various water audit methodologies historically employed and concluded that the method ultimately adopted by AWWA and IWA is the most robust.  Guidance is also provided on the assessments and strategies to employ to launch an effective water loss control program.  http://www.waterrf.org/Pages/Projects.aspx?PID=2811

Research Report for Project 2928  Leakage Management Technologies, Water Research Foundation, 2007  This project piloted successful international leakage management interventions in several North American water utilities.  Techniques that were demonstrated included district metered areas, pressure management, and inline leak detection for large diameter transmission lines.  The conclusions found that, with the use of site-specific design elements, these techniques have applicability in North American water utilities and offer new means to control leakage effectively. http://www.waterrf.org/Pages/Projects.aspx?PID=2928

Research Report for Project 4372a  Real Loss Component Analysis: a Tool for Economic Water Loss Control, Water Research Foundation, 2014  This project reviewed data from hundreds of utility water audits – both validated and un-validated – to assess the water loss standing of North American water utilities. The project also developed a useful spreadsheet software tool that allows users to input data on their leakage trends with the resultant output that defines the strategic activities that the water utility can undertake to economically the types of leakage that is occurring in their water distribution system. http://www.waterrf.org/Pages/Projects.aspx?PID=4372

Research Report for Project 4144  Pipe Location and Leakage Management for Small Water Systems, Water Research Foundation, 2014  This project developed guidance and other information oriented towards use by small utility system managers in locating buried pipe and managing leaks associated with those pipes.  The research synthesized the project findings from case studies and other projects. http://www.waterrf.org/Pages/Projects.aspx?PID=4144 

More Information

AWE Water Loss Control Introduction 

April 2014 Water Loss Control Workshop (Presentations available for download) 

Water Audit Process Introduction 

Case Studies - The Emerging Use of Water Audits in the US