Non revenue water (NRW) is
water
Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...
that has been produced and is "lost" before it reaches the customer. Losses can be real losses (through
leak
A leak is a way (usually an opening) for fluid to escape a container or fluid-containing system, such as a tank or a ship's hull, through which the contents of the container can escape or outside matter can enter the container. Leaks are usuall ...
s, sometimes also referred to as physical losses) or apparent losses (for example through theft or
metering inaccuracies). High levels of NRW are detrimental to the financial viability of
water utilities
The water industry provides drinking water and wastewater services (including sewage treatment) to residential, commercial, and industrial sectors of the economy. Typically public utilities operate water supply networks. The water industry does ...
, as well to the quality of water itself. NRW is typically measured as the volume of water "lost" as a share of net water produced. However, it is sometimes also expressed as the volume of water "lost" per km of water distribution network per day.
Components and audits
The
International Water Association
The International Water Association (IWA) is a nonprofit organization and knowledge hub for the water sector, connecting water professionals and companies to find solutions to the world's water challenges. The IWA is headquartered in London, UK, ...
(IWA) has developed a detailed methodology to assess the various components of NRW. Accordingly, NRW has the following components:
* Unbilled authorized consumption
* Apparent losses (
water theft
Water theft is illegal tapping of water supply systems. Together with losses from water leaks in the piping, water theft is one of the major factors contributing to non-revenue water.
Thames Water estimated losses by theft to amount to 2 to per ...
and metering inaccuracies)
* Real losses (from transmission mains, storage facilities, distribution mains or service connections)
In many utilities the exact breakdown of NRW components and sub-components is simply not known, making it difficult to decide about the best course of action to reduce NRW. Metering of water use at the level of production (wells, bulk water supply), at key points in the distribution network and for consumers is essential to estimate levels of NRW (see
Water metering
Water metering is the practice of measuring water use. Water meters measure the volume of water used by residential and commercial building units that are supplied with water by a public water supply system. They are also used to determine flo ...
).
In most developed countries, there are no or very limited apparent losses. For developing countries the World Bank has estimated that, on average, apparent losses – in particular theft through illegal connections – account for about 40% of NRW. In some cities, apparent losses can be higher than real losses. Reducing apparent losses from illegal connections is often beyond what a utility can achieve by itself, because it requires a high level of political support. Illegal connections are often in
slum
A slum is a highly populated urban residential area consisting of densely packed housing units of weak build quality and often associated with poverty. The infrastructure in slums is often deteriorated or incomplete, and they are primarily inh ...
s, which means that their regularization in some cases particularly affects the poor. A water audit is a key tool to assess the breakdown of NRW and to develop a program for NRW reduction. Often a distinction is made between unvalidated and validated water audits.
[Johnson, Paul V.]
Unaccounted-for water puzzle: More than just leakage
Florida Water Resources Journal, February 1996 Unvalidated water audits are desktop studies that include many estimates and their results can have an error range for real losses of ± 50% or more. Its main value is to identify where it is necessary to reduce the uncertainty of the water audit through validation. Validating water audits is a complex process that involves testing of production water meters, testing of a representative random sample of customer meters, eliminating systematic errors created through the billing process and validating the number of illegal connections through aerial mapping, field surveys or cross-references between various existing databases. In developing countries it is rare to find utilities that have undertaken validated water audits, and even in developed countries they are not systematically used. The
American Water Works Association
American Water Works Association (AWWA) is an international non-profit, scientific and educational association founded to improve water quality and supply. Established in 1881, it is a lobbying organization representing
a membership (as of 2012) o ...
(AWWA) has developed Water Audit Software which allows utilities to rate the overall degree of validity of their water audit data. Guidance on loss control planning is given based upon the credibility of the data and the measure of losses displayed by the water audit.
NRW is sometimes also referred to as unaccounted-for water (UFW). While the two terms are similar, they are not identical, since non-revenue water includes authorized unbilled consumption (e.g. for
firefighting
Firefighting is the act of extinguishing or preventing the spread of unwanted fires from threatening human lives and destroying property and the environment. A person who engages in firefighting is known as a firefighter.
Firefighters typically ...
or, in some countries, for use by religious institutions) while unaccounted-for water excludes it.
[International Benchmarking Network for Water and Sanitation(IB-NET)]
Non-Revenue Water at the International Benchmarking Network for Water and Sanitation Utilities (IB-NET)
Indicators
The most commonly used indicator to measure NRW is the percentage of NRW as a share of water produced. While this indicator is easy to understand and indeed has been widely used, it has increasingly been recognized that it is not an appropriate indicator to benchmark NRW levels between utilities or even to monitor changes over time. When losses in terms of absolute volume are constant the percentage of NRW varies greatly with total water use, i.e. if water use increases and the volume of losses remains constant the percentage of NRW declines. This problem can be eliminated by measuring NRW not as a share, but in terms of absolute losses per connection per day, as recommended by the
International Water Association
The International Water Association (IWA) is a nonprofit organization and knowledge hub for the water sector, connecting water professionals and companies to find solutions to the world's water challenges. The IWA is headquartered in London, UK, ...
(IWA). Nevertheless, the use of percentage figures to compare levels of NRW remains common despite its shortcomings. The International Benchmarking Network for Water and Sanitation recommends to use different indicators (percentage, losses per connection or losses per km of network) together.
Losses per kilometer of network are more appropriate to benchmark real losses, while losses per connection are more appropriate to benchmark apparent losses.
The concept of NRW as an indicator to compare ''real'' losses of water utilities has been criticized as flawed, particularly because real losses depend to some extent on factors largely outside the control of the utility, such as topography, age of network, length of network per connection and water use per capita. As an alternative indicator for the measurement of real losses an Infrastructure Leakage Index (ILI) has been developed. The ILI is defined as the ratio of Current Annual Real Losses (CARL) to Unavoidable Annual Real Losses (UARL).
Overview of NRW levels
Expressed as a share of produced water
The following percentages indicate the share of NRW in total water produced:
* Singapore 5% (UFW)
* Batam Island - Indonesia 15% (2019) - (ATB Batam)
* Denmark 6%
* Netherlands 6%
* Germany 7% (2005)
[Metropolitan Consulting Group: VEWA - Vergleich europaeischer Wasser- und Abwasserpreise, p. 4 of the executive summar]
The study states that its methodology allows for an accurate comparison, including water used to flush pipes and for firefighting.
* Japan 7% (2007)
[Mohamed Benouahi and Satoru Ued]
Accountable Water and Sanitation Governance:Japan's Experience
in:Water in the Arab World. Management Perspectives and Innovations, World Bank, 2009, p. 131-156, retrieved on January 6, 2011
* Eastern Manila, Philippines 11% (2011), down from 63% in 1997
* Tunisia 18% (2004)
[Private Sector Participation and Regulatory Reform in Urban Water Supply: The Middle East and North African Experience, Edouard Perard, OECD Experts’ Meeting on Access to Drinking Water and Sanitation in Africa, Paris, December 1, 2006]
* England and Wales 19% (2005)
[
* MWA, Bangkok 25% (2012)
* France 26% (2005)][
* Dhaka, Bangladesh 29% (2010)][Taqsem Khan:The performance challenges of Dhaka WASA, in Global Water Intelligence:Focusing on performance, Global Water Summit 2011, p. 50-52.]
* Italy 29% (2005)[
* Chile 34% (2006)
* Eastern Jakarta, Indonesia 42% (2016), down from 59% in 1998]
* Amman, Jordan 34% (2010)
* Mexico 51% (2003)
* Western Jakarta, Indonesia 39% (2011), down from 57% in 1998
*Kosovo 58%
* Bauchi state, Nigeria 70%
* Yerevan, Armenia 72% (1999)[Asian Development Bank, Melissa Alipalo, Anand Chiplunkar, Mai Flor]
Yerevan Water Supply. Going Private Gradually - Armenia makes gains taking transitional route through private water
, August 2008
* Lagos, Nigeria 96% (pre-2003)
Expressed in cubic meters per network length
The following figures are expressed in cubic meters per kilometer of distribution network per day:
* Netherlands 1.5[
* Denmark 1.6][DANVA:Water in figures. DANVA’s Benchmarking and Water Statistics 2010]
quoting OFWAT for figures outside Denmark, retrieved on April 16, 2012
* Germany (towns) 0.7–2.4
* Germany (large cities) 2.4–5
* Australia 4.4[
* Malmö, Sweden 5]
* California Water Service Company 6
* Portugal 7[
* England and Wales 10][
* Helsinki 18]
* Penn American Water 19
* Russia 20 (2006)[
* Stockholm 21]
* Scotland 21.3[
* Illinois American Water 26]
* Ireland 29
* Brazil 42 (2006)[
* China 52 (2006)][Greg Browde]
Stepping Up: Improving the performance of ChinaÕs urban water utilities
World Bank, 2007, p. 12
* Bucharest 350 in 2000 and 176 in 2007
These levels are given per km of network, not per connection.
Benefits of NRW reduction
The World Bank has estimated the total cost of NRW to utilities worldwide at US$14 billion per year. Reducing by half the current levels of losses in developing countries, where relative losses are highest, could generate an estimated US$2.9 billion in cash and serve an additional 90 million people.
Benefits of NRW reduction, in particular of leakage reduction, include
* financial gains from increased water sales or reduced water production, including possibly the delay of costly capacity expansion;
* increased knowledge about the distribution system;
* increased firefighting capability due to increased pressure;
* reduced property damage;
* reduced risk of contamination.[Lahlou, Zacharia M.]
Leak Detection and Water Loss Control
National Drinkingwater Clearinghouse at West Virginia University, 2001, p. 2
* More stabilized water pressure throughout the system
Leakage reduction may also be an opportunity to improve relations with the public and employees. A leak detection program may be highly visible, encouraging people to think about water conservation. The reduction of commercial losses, while politically and socially challenging, can also improve relations with the public, since some consumers may disgruntled to know that others are underbilled.
In the specific context of the United States NRW reduction can also mean reduced legal liability and reduced insurance payments.
Programs to reduce NRW
Reducing NRW is a complex process. While some programs have been successful, there are many pitfalls.
Successful programs
In the following cities high levels of non-revenue water have been substantially reduced:
* Dolphin Coast (iLembe), South Africa, 30% in 1999 to 16% in 2003 by the water privatization, private utility Siza Water Company;[Philippe Marin]
Public-Private Partnerships for Urban Water Utilities Experiences in Developing Countries
World Bank, 2009, p. 76-88
* Istanbul
Istanbul ( , ; tr, İstanbul ), formerly known as Constantinople ( grc-gre, Κωνσταντινούπολις; la, Constantinopolis), is the List of largest cities and towns in Turkey, largest city in Turkey, serving as the country's economic, ...
, Turkey, from more than 50% prior to 1994 to 34% in 2000 by the public utility ISKI;
* Jamshedpur
Jamshedpur (, ) or Tatanagar is the largest and most populous city in Jharkhand and the first planned industrial city in India. It is a Notified Area Council and Municipal Corporation and also the headquarter of the East Singhbhum district. It ...
, India, from an estimated 36% in 2005 to 10% in 2009 by the private utility Jamshedpur Utilities and Services Company;
* East Manila
Manila ( , ; fil, Maynila, ), officially the City of Manila ( fil, Lungsod ng Maynila, ), is the capital of the Philippines, and its second-most populous city. It is highly urbanized and, as of 2019, was the world's most densely populate ...
, Philippines, from 63% in 1997 to 16% in 2009 by the private utility Manila Water;
* Ouagadougou
Ouagadougou ( , , ) is the capital and largest city of Burkina Faso and the administrative, communications, cultural, and economic centre of the nation. It is also the country's largest city, with a population of 2,415,266 in 2019. The city's n ...
and other cities in Burkina Faso, by the public utility Office National de l’Eau et de l’Assainissement (ONEA) which achieved a level of 16% in 2008;
* Paranaguá
Paranaguá (''Great Round Sea'', in Tupi) is a city in the state of Paraná in Brazil. Founded in 1648, it is Paraná's oldest city. It is known for the Port of Paranaguá, which serves as both the sea link for Curitiba, to the west and the cap ...
, Brazil, from 58% in 2000 to 38% in 2006 by a private utility;
* Phnom Penh
Phnom Penh (; km, ភ្នំពេញ, ) is the capital and most populous city of Cambodia. It has been the national capital since the French protectorate of Cambodia and has grown to become the nation's primate city and its economic, indus ...
, Cambodia, from 72% in 1993 to 6% in 2008 by the public utility Phnom Penh Water Supply Authority (PPWSA) (see Water supply in Phnom Penh
The Phnom Penh Water Supply Authority (PPWSA) ( km, រដ្ឋាករទឹកស្វយ័តក្រុងភ្នំពេញ) is the municipal water utility that serves Cambodia's capital Phnom Penh and surrounding areas.
In 1992 it pr ...
for more details);
* Five municipalities in Rio de Janeiro State
Rio de Janeiro () is one of the 27 federative units of Brazil. It has the second largest economy of Brazil, with the largest being that of the state of São Paulo. The state, which has 8.2% of the Brazilian population, is responsible for 9.2% of ...
(Prolagos), Brazil, from 60% in 2000 to 36% in 2006 by a private utility;
* Rabat
Rabat (, also , ; ar, الرِّبَاط, er-Ribât; ber, ⵕⵕⴱⴰⵟ, ṛṛbaṭ) is the capital city of Morocco and the country's seventh largest city with an urban population of approximately 580,000 (2014) and a metropolitan populati ...
, Morocco, from 32% in 2002 to 19% in 2008 by the private utility REDAL;[Global Water Intelligence:Debtors impact Veolia Maroc's cashflow, February 2010, p.8]
* Cities in Senegal, from 32% in 1996 to 20% in 2006 by the private utility Senegalaise des Eaux;
* Tangiers
Tangier ( ; ; ar, طنجة, Ṭanja) is a city in northwestern Morocco. It is on the Moroccan coast at the western entrance to the Strait of Gibraltar, where the Mediterranean Sea meets the Atlantic Ocean off Cape Spartel. The town is the capit ...
, Morocco from 41% in 2002 to 21% in 2008 by the private utility Amendis.
* 8 districts in Johor
Johor (; ), also spelled as Johore, is a States and federal territories of Malaysia, state of Malaysia in the south of the Malay Peninsula. Johor has land borders with the Malaysian states of Pahang to the north and Malacca and Negeri Sembilan ...
State, Malaysia, from 38% in 2004 to 29% in 2011 by the private utility Ranhill Utilities
* Western part of Metro Manila
Manila ( , ; fil, Maynila, ), officially the City of Manila ( fil, Lungsod ng Maynila, ), is the capital of the Philippines, and its second-most populous city. It is highly urbanized and, as of 2019, was the world's most densely populate ...
, Philippines, NRW was reduced from 1,580 million liters per day in 2008 to 650 million liters per day in 2014 in cooperation with the private utility Miya.
These successes were achieved by both public and private utilities, in every continent, in emerging countries as well as very poor countries, in large cities and smaller towns. All required a long-term commitment by utility management and the government – local or national – over a period of at least four years.
Pitfalls of programs
Many programs to reduce NRW have failed to achieve their objectives, sometimes from the onset and sometimes only in the long run. Often they focus on real losses without sufficient attention being paid to apparent losses. If programs achieve an initial reduction in NRW levels, they often increase again over the years to the same or even higher levels than before the program. Both apparent and real losses have a natural tendency to increase if nothing is done: more leakage will occur, there will be more defective meters, and information on customers and networks will become more outdated. In order to sustain NRW at low levels, investments in fixing leaks and replacing meters are insufficient in the best case and ineffective in the worst case. To achieve permanent results, management procedures related to a utility's organization, procedures and human resources have to be changed.[Michel Vermersch and Alex Rizzo: Designing an action plan to control non-revenue water, in: Water 21, Magazine of the ]International Water Association
The International Water Association (IWA) is a nonprofit organization and knowledge hub for the water sector, connecting water professionals and companies to find solutions to the world's water challenges. The IWA is headquartered in London, UK, ...
, April 2008, p. 39-41
Additionally the implementation of an Intelligent Pressure management system is an efficient approach to reduce the total real losses in the long term. It is one of the most basic and lucrative forms of optimizing a system and generally provides fast investment paybacks.[J. Thornton, R. Sturm and G. Kunkel: Controlling Real Losses - Pressure Management, in Water Loss Control, 2008, McGraw-Hill, p. 301-343]
According to a study by the World Bank
The World Bank is an international financial institution that provides loans and grants to the governments of low- and middle-income countries for the purpose of pursuing capital projects. The World Bank is the collective name for the Interna ...
some of the reasons why NRW levels in developing countries have not been reduced significantly are the following.
Another source quotes the seven most frequent reasons for failure of NRW reduction programs as follows:
* Poor design
* Diagnoses based on preconceptions rather than experimentation
* Partial implementation
* Failure to mobilize the necessary human and financial resources
* Lack of coordination between the components of the program
* Underestimation of the difficulties
* Underestimation of the time factor
Optimal level
There is some debate as to what is an economically optimal level of leakage or, speaking more broadly, of NRW. From a financial or economic point of view it is not appropriate to try to reduce NRW to the lowest possible level, because the marginal cost
In economics, the marginal cost is the change in the total cost that arises when the quantity produced is incremented, the cost of producing additional quantity. In some contexts, it refers to an increment of one unit of output, and in others it r ...
of reducing NRW increases once the cheaper options have been exploited. Once the marginal cost of reducing NRW exceeds the marginal benefits or water savings, an economic optimum has been achieved. Benefits should be measured through reduced production costs if reduction of NRW results in lower water production, through the avoided costs of additional supply capacity if the system is close to the limit of its capacity and demand is growing, or through the value of water sold if reduction of NRW results in additional water sales. The latter can be done by valuing water through water tariffs (financial value) or through the willingness to pay by customers (economic value). There are fewer financial incentives for a utility to reduce NRW if water production is cheap, if there is no or little metering (so that revenues thus are independent of actual consumption), or if volumetric tariffs are low.
In the United Kingdom the assessment of economic levels of leakage has a long history. The first national study on the topic was published in 1980 setting down a methodology for the assessment of economic leakage levels. This led to the implementation of sectors (District Metered Areas) in most water companies in the UK. The findings were reported in a major national research program in 1994. As a result of a drought in 1995/96 a number of companies initiated major leakage management programmes based on economic assessments. The situation in other parts of the world is quite different from the UK. Particularly in developing countries sectorisation is very rare and proactive leakage control limited. The benefits of pressure management are not widely appreciated and there is generally no assessment of the economic level of leakage.
From a public health and drinking water quality point of view it is being argued that the level of real water losses should be as low as possible, independently of economic or financial considerations, in order to minimize the risk of drinking water contamination in the distribution network.
The World Bank
The World Bank is an international financial institution that provides loans and grants to the governments of low- and middle-income countries for the purpose of pursuing capital projects. The World Bank is the collective name for the Interna ...
recommends that NRW should be "less than 25%", while the Chilean water regulator SISS has determined a NRW level of 15% as optimal in its model of an efficient water company that it uses to benchmark service providers. In England and Wales NRW stands at 19% or 149 liter/property/day.[OFWAT. 2008]
Water industry facts and figures
In the United States the American Water Works Association
American Water Works Association (AWWA) is an international non-profit, scientific and educational association founded to improve water quality and supply. Established in 1881, it is a lobbying organization representing
a membership (as of 2012) o ...
's (AWWA) Water Loss Control Committee recommended in 2009 that water utilities conduct annual water audits as a standard business practice. AWWA recommends that water utilities should track volumes of apparent and real losses and the annual cost impacts of these losses. Utilities should then seek to control excessive losses to levels that are economic for the water utility. In 1999 the California Urban Water Conservation Council
California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the mo ...
identified a 10 percent benchmark for non-revenue water.[Richard G. Sykes, Andrew K. Enos and Ronald L. Bianchetti, East Bay Municipal Utility District, Oakland, California, US]
Monitoring and Managing Unaccounted for Water, Proceedings of the International Symposium on Efficient Water Use in Urban Areas - Innovative Ways of Finding Water for Cities
8 to 10 June 1999, quoted on the website of UNEP
The United Nations Environment Programme (UNEP) is responsible for coordinating responses to environmental issues within the United Nations system. It was established by Maurice Strong, its first director, after the United Nations Conference on th ...
's International Environmental Technology Centre (IETC)
See also
*Water supply
Water supply is the provision of water by public utilities, commercial organisations, community endeavors or by individuals, usually via a system of pumps and pipes. Public water supply systems are crucial to properly functioning societies. Thes ...
*Water meter
Water metering is the practice of measuring water use. Water meters measure the volume of water used by residential and commercial building units that are supplied with water by a public water supply system. They are also used to determine flo ...
*Utility
As a topic of economics, utility is used to model worth or value. Its usage has evolved significantly over time. The term was introduced initially as a measure of pleasure or happiness as part of the theory of utilitarianism by moral philosopher ...
References
{{DEFAULTSORT:Non-Revenue Water
Water supply