Jose de la Fuente on how advanced detection techniques relying on data analysis can plug leakages in water transmission and distribution mains
Water loss is a major concern for most water utilities worldwide, affecting not only operational processes but also financial, social and environmental aspects of the utility. A 2006 World Bank report declared that the total cost of non-revenue water (NRW) for water utilities worldwide can be conservatively estimated at US $14 billion per year, with two thirds of it occurring in the developed countries.
Water losses are real (physical losses) or apparent (economic or commercial losses). Real water losses reflect water lost from the network and not used, such as leaks in the distribution system, overflows from reservoirs and washouts. Apparent water losses reflect water that is consumed by users but unmetered, or not correctly metered, and consequently taken into account. Here, we refer primarily to real water losses focusing on the detection of leaks in transmission and distribution mains where most network water is physically lost. We also discuss how leak management solution integrates with the enterprise SCADA system and uses the system's real-time data to promptly identify the presence of leaks or bursts and minimises costs and other adverse impacts for the utility.
Hunting down NRW leaks
Traditionally, water loss control activities minimise the effects of inefficient processes and support operations stressed by water supply limits. Even well-managed utilities and those operating with ample supply of fresh water have many reasons to go after water loss.
Shareholders continuously seek financial optimisation. The reduction of NRW can result in an increase in revenues where the water demand is not entirely satisfied; it reduces the expense of treating and pumping lost water; and leak detection and repair is often a less costly alternative to tapping new water sources.
Utilities' water loss control policies increasingly impact stakeholders through:
- Increasingly stringent leakage guidelines and targets
- Customers who are more cognisant of water usage and leakage
These concerns impact utilities, affecting corporate image, imposing penalties, tariff caps, and service contract breaches. Leakage simply cannot be ignored.
A sustainable strategy to control real water loss should embrace four main tactics:
- Active Leakage Control (ALC)
- Pipeline and asset management
- Speed and quality of repairs
- Pressure management
Active Leakage Control proactively searches for hidden leaks. Basic ALC consists of periodically "sweeping" the water network to identify the presence of leaks in water mains. A more comprehensive ALC approach is to make regular network flow measurements to identify new leaks quickly. The sooner a leak is detected, the sooner it can be located and repaired. Detecting leaks quickly after formation requires real-time or near-real-time analysis of hydraulic parameters (flow, pressure, and level) throughout the water distribution system.
SCADA for leak detection
The Supervisory Control and Data Acquisition (SCADA) system is an ideal platform for performing the advanced analysis that promptly identifies leakage presence. Yet many water utilities still do not exploit their SCADA system to the fullest, often using it to collect periodic flow data to calculate water balances and estimate water loss. In contrast, the oil industry extensively uses software tools that, installed on top of the SCADA system, proactively execute leak detection.
Leak detection systems based on field data typically apply one of these leak detection techniques:
Techniques 1, 2, and 3 typically detect and locate bursts in water transmission schemes where metering accuracy is usually high, operations are steady, and the presence of non-metered customers is negligible.
Technique 4 is typically applied to track leaks within distribution networks, preferably at a district-metered-area (DMA) level, integrating data from the DMA inlet meter with the SCADA system.
In a typical water supply system, real losses might exist in the distribution networks and in transmission schemes. Therefore, it might be necessary to deploy more than one of the above-mentioned techniques in order to achieve comprehensive leak detection. All the above methods require analysis of data collected by the SCADA system. Analysis can be simple or extensive, and without specific software calculations, comparisons with historic data and exchange of information with other enterprise systems would be extremely difficult.
At Telvent, we have packaged methods to perform real-time network analysis and modelling for leakage detection as the Leak Management application of the Telvent Water Management Suite solution. They work within a single software framework to analyse real-time data from SCADA systems and allow the water operator to assess the presence of leaks across the network. The Telvent Leak Management solution helps affect efficient ALC by immediately detecting a new leak occurrence. Reports and alarms are issued immediately and the system allows the user to choose from five leak detection methods.
Smart Water Networks
Integrated, modular systems deliver targeted solutions, ability to adapt and grow. Every time the utility gathers, treats, and distributes water - every time a pump starts, every time a tank is filled, every time a tap is opened - it generates data that can reveal valuable network operations and business insight. The challenge is to transform all of this data into meaningful information and transfer it quickly and accurately to all internal and external functions and departments that can use it. A Smart Water Network not only provides enhanced automated process control but can fully process data in real time to save water and labour costs, optimise compliance and security, and assure good customer service. A Smart Water Network integrates very well with legacy systems, making information transformation and flow available to anyone using the existing technology, and thus helps realise the full potential of all infrastructure investments, past and future. The Smart Water Network can adapt to the utility's processes, provided that necessary standard water utility information is available. Yet specific challenges can create different priorities and different information needs. The Smart Water Network must be flexible and open in its architecture to integrate as much as possible with the existing technology base and accommodate extensions and system enhancements to meet future needs.
Information from a well-integrated system is accurate, secure, and timely and helps the entire utility make better decisions more quickly. The cross-departmental nature of the Smart Water Network even allows the utility to take proactive actions in areas where it was not possible before because managing water leaks impacts several departments. The utility operating with a Smart Water Network has reliable information that can help prevent leaks and expedite location and repair when they do occur, saving costs and water:
Real time information helps to confirm an actual leak and the need for action. This same real-time SCADA information triggers a review order in the maintenance system, which is linked to a geographic information system (GIS). The GIS query, identifies where the problem exists, which course of action will minimise impact on the rest of the network, and notify the control room as to which valves must be closed. Using the client database, the GIS identifies the customers who will be impacted, allowing notification to take place before remedial action. Integration with the Enterprise Resource Planning system (ERP) can create time and cost information regarding the impact on business. Any event triggers a series of information activities that helps departments work together to make the best decisions while measuring and minimising the event's impact.
The best way for utilities to establish a Smart Water Network is to follow a phased approach:
- Prioritise issues across the organisation
- Look at which systems are already in place and what can be done with them
- Decide which new investments are needed to complement existing capabilities
Most water utilities have a control system and a hydraulic model, but few link these two systems together for real-time leak detection, or link them with a GIS and a maintenance management system to increase leak management efficiency. Fewer link these systems to an ERP to know the total cost of their leaks. The water utility that implements monitoring, control, and information management processes through a suite of modular, integrated solutions will see immediate improvements in operations efficiency and security and will continually reap benefits as its needs change or expand.
The author is GCC Area Manager-Water Utilities, Telvent
© H2O 2010
