How to reduce non-revenue water and water loss
REDUCING non-revenue water brings huge benefits, not just to utilities but to the environment and society as a whole. The more water that gets where it’s needed it and is paid for, the better for the financial viability of the utility. The less water that is wasted, the less we need to take from the environment and the less chemicals and energy we need to treat and pump it. The more accurately water is measured, the better investment will be directed.
In this blog we look at techniques to combat non-revenue water and how to devise a programme which reduces the unnecessary water loss it causes.
Reducing water loss from pipeline networks
Not all non-revenue water is avoidable. In fact, some of it happens for very good reasons, for example because it’s used for fire-fighting or flushing pipes to ensure better water quality. Even leakage, which makes up the majority of NRW, can never be reduced to zero. As fast as leaks are fixed, they spring up somewhere else.
The International Water Association has defined three main categories of NRW:
- real (physical) losses, mostly leakage
- apparent (commercial) losses leading to under-billing, and
- unbilled authorised consumption.
Each category needs different approaches to reduction. For instance, in the case of unbilled authorised consumption and apparent losses, better internal monitoring and management could help. For leakage, a combination of pressure management, detection and repair or even pipeline replacement is most effective.
Leakage is usually the biggest NRW headache for most water network operators. As well as being costly to solve, left unaddressed it can lead to substantial collateral third party damage, and in an era of increasing water scarcity it is a financial and reputational risk. For this reason, most improvement programmes tend to focus on reducing real water losses.
The good news is that there are multiple techniques and tools to reduce the impact of leakage and improve rates of detection and repair. New technologies based on data and AI are also helping identify patterns and areas of risk allowing for strategic prevention.
Setting a water loss reduction target
Studies suggest that reducing NRW is usually more cost effective than increasing the water supply. In part of Manila, Philippines, the water utility managed an average increase in water consumption of 4.75% a year for 13 years without increasing production, just by reducing its year-on-year percentage of NRW.
Unfortunately, there is no one-size-fits-all approach. The optimum level of reduction for different utilities varies widely depending on things like network length, or number of connections and utility size. Recent research in the US by the University of California demonstrated this. The US has tens of thousands of water utilities, some of them very small. The study found that reducing distributional losses could be much more cost-effective than boosting supplies and even household water conservation strategies, but the potential varied substantially across utilities.
Setting an appropriate reduction target means working out how much of each type of NRW you have, how much of it is unavoidable and how much of the what’s left is economic to recover.
- NRW Water Balance: A volumetric assessment of all the different types of non-revenue water in a pipeline network is called a water balance , also referred to as a water audit. The standardised best practice method used around the world is the IWA’s Water Balance. Many regions have their own modified versions, some with free software packages, such as the AWWA’s Water Audit in the US. As the largest type of NRW, most improvement programmes focus on reducing real water losses. The numerical value in the water balance which is concerned with leakage is Current Annual Real Losses (CARL).
- Unavoidable Annual Real Losses (UARL): Leaks on public water systems are stubbornly difficult and expensive to locate and fix. An estimated 90% of leakage never shows above ground. It’s also a moving target. Even if all leaks were fixed today, more would occur tomorrow. It’s in the nature of large water pipeline systems. Recognising this problem, the IWA Water Loss Taskforce developed a calculation for the lowest technically achievable leakage volume in any given water system when it is in good condition and well-managed. This figure of Unavoidable Annual Real Losses, or UARL, is a ‘best case’ score taking account of network-specific characteristics like mains length, and the number & length of service connections at a stated average pressure.
- Economic level of leakage (ELL): In the real world, what is technically achievable may not always be economically viable. The Economic Level of Leakage, or ELL, is a cost-benefit calculation, defined as the lowest level of leakage achievable before the cost of further reduction becomes more expensive than the cost of producing water. A Sustainable ELL, or SELL, takes the environmental and societal impacts of addressing leakage into account as well – such as the costs of disruption to society from road works, effects on economic activities like tourism in water stressed areas or the carbon costs associated with treating or pumping of water. If the cost of producing water increases, the ELL drops. In median US utilities, UCDavis researchers found that reducing leakage was a cheaper way of addressing water scarcity than water recycling, desalination and even conservation campaigns. The difference between the Current Annual Real Losses and the Economic Leakage Level is what’s known as economically recoverable water losses.
The Infrastructure Leakage Index and Economic Level of Leakage
Water loss indicators
Measures of NRW performance are called indicators. The most common shows NRW as a simple percentage of the amount of water put into a water system (also called % of system input volume, or SIV). Another popular indicator is water lost per connection per day. However, both can be misleading as neither takes account of inherent differences between water networks. Experts prefer the Infrastructure Leakage Index, or ILI, as the international indicator for measuring how well a distribution network is managed.
The Infrastructure Leakage Index (ILI) is calculated as the ratio of Current Annual volume of Real Losses (CARL) to Unavoidable Annual Real Losses (UARL), with some corrections for small systems. The perfect ILI is 1, where CARL and UARL are the same. But acceptable ILIs are usually based on the Economic Level of Leakage and are usually much higher.
ILIs are considered to be the most reliable way to compare technical real losses management performance at a national and international level and many Global ILIs are published by the IWA.
Steps to reduce NRW and water loss
A typical programme to control water loss usually starts with a water audit. This is used to identify areas where improvements can be made and set targets. Finally, interventions are evaluated and monitored.
Equipment like meters, pressure reduction valves and digitised systems makes assessing, reducing and evaluating NRW programmes easier and more accurate, especially if networks are subdivided into district metered areas (DMAs). But it is always worth trying to establish a water balance, even if main elements are based on estimates.
- Step 1: Audit non-revenue water: The first step is to assess NRW, identify data gaps and select interventions by carrying out a water balance. Measurements or estimations of all the water produced, imported, exported, used or lost is used to quantify the different types of NRW. It is based on a year’s worth of data on water supply, customer usage, authorized unbilled unmetered water volumes, meter testing and/or calibration over the space of one year, as well as figures for mains length, service connections, system operating system pressure, retail rate and production cost. Appropriate performance indicators and interventions are selected on a cost-benefit basis.
- Step 2: Deliver interventions to reduce NRW: The next step is to put the action plan in place. This could include changes to operational, metering or maintenance processes, active leakage control, capital investment in metering, monitoring and management equipment and pipeline repairs. It can also include some strategic preventative measures such as changes to policy, construction and design standards and targetted pipeline replacement. All these interventions have the potential to generate more reliable data that confirms or refines the losses identified in the audit stage.
- Step 3: Monitor water loss performance: A good choice of appropriate, targetted, consistent indicators using standard units of measurement allows utilities to monitor their water loss performance over time. This evidence is vital for benchmark comparisons, continuous improvement and regulatory reporting.
- Step 4: Predict and prevent water loss: Although not traditionally part of the water loss control programme, continued targetted water loss interventions and accumulated data, especially in combination with digitised models, give opportunities for leak prediction and strategic prevention using AI.
FIDO AI: data insight for end-to-end NRW reduction
FIDO Tech has developed a sophisticated water loss AI which uses advanced acoustic analysis to help utilities find, locate and reduce non-revenue water. FIDO AI accurately identifies leaks and, most importantly, ranks them by size, even in the noisiest networks, and regardless of pipe material or condition. This single piece of actionable insight on leak size sets us apart. It enables us to prioritise repairs, reducing leak runtime and maximising water loss reduction.
FIDO AI treats leaks as assets, tracking and learning from them on an endless verified feedback loop getting more and more accurate all the time. And, our versatile AI-enabled sensors can be used at every stage of the NRW process: as sensors, correlators and ground microphones. They operate without thresholds so nothing gets missed. Even small leaks can be tracked until they degrade or aggregate to a point they become economic to repair.
The addition of an optional IoT comms device enables continual network monitoring with automated AI leak detection delivered daily.
FIDO’s AI solutions Network Monitor and Leak Locate have already seen multiple successes around the world. We partnered with Northumbrian Water to reduce leakage by 37%. We are also working with Microsoft and Thames Water on a first-of-a-kind collaboration to address water leakage in London’s public water network.
For more information on any of FIDO’s solutions contact us today.
