- Email: [email protected]
Maximising the benefits of desalination
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DESALINATION !In
ELSEVIER
Desalination 138 (2001) 41-46
www.elsevier.com/locate/desal
Maximising the benefits of desalination Charalambos (Bambos) Charalambousa*, Mike Setford b aWater Board of Lemesos (Limassol), P.O. Box 50225, 66 Franklin Roosevelt Avenue, 3602 Lemesos (Limassol), Cyprus Tel. +357 (5) 574457; Fax +357 (5) 564382; e-mail: [email protected] ~Halcrow Water Services, Kent, UK Tel. +44 (1634) 244-114; Fax +44 (1634) 244-388; e-mail: [email protected]
Received 13 February 2001; accepted 27 February 2001
Abstract
Water shortages are caused by various factors, including extreme shortages of rainfall and increased demand. This paper deals with water conservation relating in particular to the reduction of leakage. Non Revenue Water, especially in cases where desalinated water is introduced into a water system. Desalination is a significant investment by an organisation and therefore it is most important to maximise the benefits of such investment. Keywords: Water shortage; Desalination; Leakage reduction strategy
1. Introduction
Desalination provides an invaluable water resource in countries that suffer regular water shortages and where natural resources are limited. The cost o f desalination has been relatively high compared to traditional treatment methods for ground or surface water. Continuous advancement in the field of membrane technology has resulted in desalinated water being *Corresponding author.
produced nowadays at a cost, which in some cases is comparable to the cost of traditionally treated surface water. The introduction o f desalinated water into a system represents a significant investment by any organisation and it is therefore most important to maximise the benefits o f such investment through cost effective water conservation throughout the water supply process. This paper deals with water conservation relating in particular, to the reduction o f leakage/ Non Revenue Water (NRW), where NRW in basic terms, is the difference between the volume
Presented at the European Conference on Desalination and the Environment." Water Shortage, Lemesos, Cyprus, 28-31 May 2001.
0011-9164/01/$-- See front matter © 2001 Elsevier Science B.V. All rights reserved PII: S 0 0 1 1 - 9 1 6 4 ( 0 1 ) 0 0 2 4 2 - 9
42
C. Charalambous, M. Setford / Desalination 138 (2001) 41-46
of water produced and the volume of water sold. NRW comprises two main components, physical losses, i.e. leakage from the water supply system and apparent losses, which include those due to meter inaccuracy, mains flushing, fire fighting and illegal use. To demonstrate the benefit of having an effective NRW reduction strategy and programme, case studies are described for Lemesos in Cyprus (Water Board of Lemesos) and for the South East of England (Mid Kent Water plc). Both organisations have suffered water shortages for many years, albeit for different reasons. Within Cyprus, water shortages have been caused by various factors, including extreme shortages of rainfall and increased demands. This has lead to water supplies being intermittent in many areas of Cyprus for the last four years. Within the South East of England, water shortages have occurred due to groundwater resources becoming increasingly limited as a result of rising demand and a growing population. There were also several years of drought during the mid nineties which exacerbated the water shortage problem. Despite these shortages, this area of the UK has been very fortunate, in that, they have never suffered intermittent water supplies. Consequently, both organisations have adopted an active leakage/Non-Revenue Water reduction policy for many years and as a result, both can now claim to have reduced their levels of NRW to economic levels within their respective countries. The methodology and approach that the two organisations have adopted were quite similar despite the cultural and climatic differences and are briefly described below.
policy for many years, along with other water companies, both organisations revised their strategy and considerably enhanced their investments on this activity during the nineties. In 1996, Halcrow Water Services provided consultancy advice to the WBL regarding their leakage/ NRW strategy and this culminated in a very similar approach being taken by both WBL and MKW from 1996 onwards. One of the key objectives of any leakage/ NRW strategy is to achieve and maintain leakage at a long-term target level based on the assessment of costs, resources, demand levels and regulatory requirements. In the case of MKW, targets were set in the early nineties based upon an empirical approach, however, over the years this work was steadily refined and economic levels of leakage targets were developed and adopted. In 1997 the UK's Water Regulator set mandatory targets for the water companies to achieve and each company has had to submit detailed calculations of their assessment of economic levels of leakage. Inevitably these submissions are rigorously challenged by the Regulator, but in the case of MKW, their recent targets were accepted and have now been achieved. For WBL, although not regulated like companies in the UK, water shortages in Cyprus have driven the need to reduce leakage/NRW and similarly the organisation has needed to set stringent targets in order to be able to provide an adequate water supply to their customers. The development and ongoing refmement of the leakage/NRW strategies within MKW and WBL, include several key components which are summarised below followed by a brief account of the results of this strategy for each of the two organisations:
2. Leakage/NRW reduction strategy Although both the Water Board of Lemesos (WBL) and Mid Kent Water pie (MKW) had operated an "active" leakage/NRW reduction
2.1. Manpower
It is most important to have well trained and motivated staff on leakage/NRW activities and
C. Charalambous, M. SeOCord/Desalination 138 (2001) 41-46 within both organisations a dedicated leakage control team was formed to tackle this vitally important area of work. Previously, the task formed part of the duties of multi-disciplined inspectorate teams. These manpower levels have been monitored against leakage levels and performance over the years to ensure staff levels have been both adequate and appropriate to fulfil the leakage/NRW reduction targets. 2.2. Flow monitoring In order to be able to work with confidence using the raw data provided from a system, it is very important for meter accuracy to be reliable from the waterworks source works through to the individual customer. A great deal of effort has therefore been expended in ensuring the reliability of this information, including meter replacement programmes and intensive calibration exercises. In addition, programmes of district metering were given high priority and the whole of the two organisations areas have now been broken down into District Metered Areas ranging between around 1000 to 3000 properties and these are continuously monitored using logging devices. Information on night-flow in particular is useful to the leakage practitioners who use the details to prioritise their leak location/management. 2.3. Pressure management High pressures within distribution systems are one of the primary causes of leaks and bursts, therefore managing the pressures on the system is a vitally important activity. Using various types of pressure reducing valves on the inlets to distribution systems, pressures can be managed in order to minimise the damage that might be caused. The investment by the two organisations on this activity has had a very significant effect on the reduction of the overall level of leakage/NRW.
43
2.4. Leak location Having prioritised areas for leak location from night flow data, the leakage teams then need to precisely locate the leak positions, which in the past has been undertaken by staff using various pieces of equipment including the basic "listening stick". However, advanced technology is now available to assist with this activity such as the use of acoustic loggers and specialist leak correlation equipment. Using this equipment, operatives can pinpoint leak positions very accurately and usually to within 0.5m. Following this activity, the leak repair teams can then be called and a repair effected. Over the years, both organisations have steadily increased their investment in modem technology and equipment. 2.5. Speed of repairs The primary aspect of a leak repair is that it should be carried out as quickly and safely as possible in order to maximise the savings and also of course, reduce the inconvenience to customers. Specific targets have been developed by MKW and WBL for repair work and these are regularly reviewed.
2. 6. Asset replacements By adopting an effective leakage/NRW reduction strategy, organisations can defer significant levels of capital expenditure particularly of resource development, including of course desalination projects. However, it is most important to link the asset replacement programme to the leakage/NRW strategy including in particular, pipeline replacements. It is also important to consider service pipe replacements, as it has recently become more apparent to people associated with this particular activity, that a significant proportion of leakage from distribution systems comes from service pipes and their associated fittings.
44
C Charalambous, M. SeOCord/Desalination 138 (2001) 41-46
2. 7. Reduction o f apparent losses
At the early stages of leakage/NRW reduction programmes, meter change-out programmes need to be developed, particularly for large commercial customers. This is necessary because old mechanical meters under-record to varying degrees (typically 3 to 15%) which inevitably reduces revenue to the water undertaking. Thus a meter change-out programme has the combined benefit of producing more reliable information for the Leakage/NRW teams and also increased revenue for the organisation as meters changed out, invariably under-record.
3. Case study 1 - Mid Kent W a t e r pie
Mid Kent Water plc is one of 16 water supply only companies within the UK, covering the South East of England and supplying on average, around 165,000m3/d of potable water to a total population of approximately 570,000 (comparable with the overall population of Cyprus). The company's origins date back to 1888 and the operational area is now 2050km 2. The area is generally rural in nature with five large townships, with the largest population of a single town being approximately 100,000. There are 4200km of pipelines, 100 operational boreholes, 33 treatment works and 74 storage reservoirs. The raw water resources emanate predominantly from underground (90%) with the remainder being provided by surface water from impounding reservoirs. It was in 1989, that the water industry within the UK became privatised and regulated by a government body called OFWAT. Following the introduction of regulation, greater emphasis was put on the activity of NRW reduction by all water companies within the UK. As a result of this pressure on the UK's Water Industry, a National Leakage Initiative body was formed which, following extensive field trials across the UK, culminated in a number of procedural
documents being developed for the various activities of this vital activity (for information, the English author was a founder member of the Steering Group to this particular body). By adopting the strategy detailed in section 2 above, the company reduced the leakage/NRW from a maximum recorded in 1987 of 47,000mVd (around 33% of total losses) to a current audited level of 29,200 mVd (around 17% of total input). This overall reduction represents a water saving that would supply an average town with a population of around 100,000 and a financial saving of£500,000 per year based upon operating costs alone. In addition, significant financial savings have been achieved as a result of the deferment of several resource development schemes. These results were achieved not only by adopting the strategy detailed in section 2 above, but also by the introduction of component based computer models such as BABE (Bursts and Background Estimates). Mid Kent were the first company in the world (together with the developer of the concepts) to use this methodology, which revolutionised their whole approach to leakage/NRW reduction. A dedicated leakage team comprising 18 staff and many other support staff developed 360 individual District Metered Areas and increased the coverage of pressure control from 20% to 60% (by area of the company). In addition, a regular programme of mains and service pipe replacements was adopted together with a rigorous meter replacement programme. If the company had not made these significant changes, not only would they have suffered severe f'mancial penalties but also, they would not have been able to sustain a continuous reliable water supply to their customers. 4. Case study 2 - Water Board o f Lemesos
The town of Lemesos is situated on the south coast of the island of Cyprus in the north-eastern
C. Charalambous, M. Setford / Desalination 138 (2001) 41-46
Mediterranean Sea, has a current population of 150,000, and is the second largest town of the island. The Water Board of Lemesos is a non-profit, semi-government organisation charged with the responsibility of supplying potable water to the town and environs of Lemesos. The Water Board was established in 1951 and as the town of Lemesos expanded, absorbing adjacent villages, the supply boundaries of the Water Board progressively moved outwards. Today the Water Board covers an area of some 65 km 2 with 674 km of underground mains. The Water Board of Lemesos is the owner of wellfields, storage reservoirs, pumping stations and underground water distribution network comprising pipelines, isolating valves, air valves, washouts, fire hydrants and house connections. The main activities of the Water Board include inter-alia planning and execution of technical projects, operation and maintenance of the water production and water supply systems and all associated financial services including collection of water revenues and determination of water tariffs. The Water Board operates a well-organised supply and distribution system with permanent pressure zones and District Metered Areas which provide a solid foundation on which to develop an effective leakage control policy. Based on the studies carded out in 1996 by Halcrow Water Services Ltd of UK, it was estimated that the Non Revenue Water figure of 19% consisted of approximately 15% leakage and 4% customer meter under-registration. Analysis of water balance data showed that virtually all the unaccounted-for water occurred within the districts, not on trunk mains. The annual total of locatable leakage was estimated to be 935.000m 3 with an annual cost value of US$500,000. The value of lost revenue through meter under-registration was estimated to be US$350,000. These initial findings had to be verified through further investigations.
45
Furthermore it was strongly recommended that a system of continuous monitoring be established in every District to analyse nightlines on a weekly basis. It was also recommended that a dedicated leakage team should be established to carry out active leakage detection in all the Districts using leakage correlation equipment. Following the above study a permanent leakage team was established in late 1998 and leakage detection and correlation equipment was purchased at the beginning of 1999. Also at this time, monitoring work commenced on a continuous basis. During 1999, a total of 41 leaks were detected and repaired, saving an estimated 140,000 m 3 of water, which would have cost the Water Board approximately US$70,000.
5. Conclusions
Demand forecasts for both MKW and WBL show a steady increase over the coming years and leakage reduction strategies as outlined above will go a long way towards offsetting this demand increase. It is important to appreciate, that any leakage/NRW strategy is a "non-stop" activity, which needs to be embraced fully by the organisation at the highest level and throughout the workforce, in order to be able to reduce the amount of water lost and maintain NRW at an economic level. We believe that both of the above organisations have achieved a great deal over the years, as can be seen from Figs. 1 and 2 and these results compare very favourably with NRW levels in other major organisations around the world, as can be seen in Fig. 3. It is clear, that the implementation of an appropriate NRW strategy within any water supply organisation, can greatly contribute towards more efficient and effective management of the available water resources, especially in parts of the world where water scarcity is a problem.
C. Charalambous, M. Setford / Desalination 138 (2001) 41-46
46
5O
oi 70
60 ~
_ I
_Ill oli|
40 so
2O 10 0
i~ 10
~.,
,.
v,
-
~1 ~.
v
-
0
,,n
0
.~
", _0
m
.--
E
~,
Fig. 1. Mid Kent Water NRW performance. Fig. 3. NRW performance by water undertakings worldwide.
30 25 20 ~15, 10, 5 O, i n oD
o~ YEARS
Fig. 2. Water Board of Lemesos NRW performance.
Footnote: With the knowledge and experience gained from the successful leakage/NRW Reduction programme in MKW over many years, Halcrow Water Services (a joint venture company between MKW and the Halcrow Group) are now providing specialist services in this field to organisations in several parts of the World. They combine the use of specialist software to develop and monitor strategies, with the use of state of the art equipment and techniques to reduce leakage/NRW to economic levels.
~¸
<"
•
r
DESALINATION !In
ELSEVIER
Desalination 138 (2001) 41-46
www.elsevier.com/locate/desal
Maximising the benefits of desalination Charalambos (Bambos) Charalambousa*, Mike Setford b aWater Board of Lemesos (Limassol), P.O. Box 50225, 66 Franklin Roosevelt Avenue, 3602 Lemesos (Limassol), Cyprus Tel. +357 (5) 574457; Fax +357 (5) 564382; e-mail: [email protected] ~Halcrow Water Services, Kent, UK Tel. +44 (1634) 244-114; Fax +44 (1634) 244-388; e-mail: [email protected]
Received 13 February 2001; accepted 27 February 2001
Abstract
Water shortages are caused by various factors, including extreme shortages of rainfall and increased demand. This paper deals with water conservation relating in particular to the reduction of leakage. Non Revenue Water, especially in cases where desalinated water is introduced into a water system. Desalination is a significant investment by an organisation and therefore it is most important to maximise the benefits of such investment. Keywords: Water shortage; Desalination; Leakage reduction strategy
1. Introduction
Desalination provides an invaluable water resource in countries that suffer regular water shortages and where natural resources are limited. The cost o f desalination has been relatively high compared to traditional treatment methods for ground or surface water. Continuous advancement in the field of membrane technology has resulted in desalinated water being *Corresponding author.
produced nowadays at a cost, which in some cases is comparable to the cost of traditionally treated surface water. The introduction o f desalinated water into a system represents a significant investment by any organisation and it is therefore most important to maximise the benefits o f such investment through cost effective water conservation throughout the water supply process. This paper deals with water conservation relating in particular, to the reduction o f leakage/ Non Revenue Water (NRW), where NRW in basic terms, is the difference between the volume
Presented at the European Conference on Desalination and the Environment." Water Shortage, Lemesos, Cyprus, 28-31 May 2001.
0011-9164/01/$-- See front matter © 2001 Elsevier Science B.V. All rights reserved PII: S 0 0 1 1 - 9 1 6 4 ( 0 1 ) 0 0 2 4 2 - 9
42
C. Charalambous, M. Setford / Desalination 138 (2001) 41-46
of water produced and the volume of water sold. NRW comprises two main components, physical losses, i.e. leakage from the water supply system and apparent losses, which include those due to meter inaccuracy, mains flushing, fire fighting and illegal use. To demonstrate the benefit of having an effective NRW reduction strategy and programme, case studies are described for Lemesos in Cyprus (Water Board of Lemesos) and for the South East of England (Mid Kent Water plc). Both organisations have suffered water shortages for many years, albeit for different reasons. Within Cyprus, water shortages have been caused by various factors, including extreme shortages of rainfall and increased demands. This has lead to water supplies being intermittent in many areas of Cyprus for the last four years. Within the South East of England, water shortages have occurred due to groundwater resources becoming increasingly limited as a result of rising demand and a growing population. There were also several years of drought during the mid nineties which exacerbated the water shortage problem. Despite these shortages, this area of the UK has been very fortunate, in that, they have never suffered intermittent water supplies. Consequently, both organisations have adopted an active leakage/Non-Revenue Water reduction policy for many years and as a result, both can now claim to have reduced their levels of NRW to economic levels within their respective countries. The methodology and approach that the two organisations have adopted were quite similar despite the cultural and climatic differences and are briefly described below.
policy for many years, along with other water companies, both organisations revised their strategy and considerably enhanced their investments on this activity during the nineties. In 1996, Halcrow Water Services provided consultancy advice to the WBL regarding their leakage/ NRW strategy and this culminated in a very similar approach being taken by both WBL and MKW from 1996 onwards. One of the key objectives of any leakage/ NRW strategy is to achieve and maintain leakage at a long-term target level based on the assessment of costs, resources, demand levels and regulatory requirements. In the case of MKW, targets were set in the early nineties based upon an empirical approach, however, over the years this work was steadily refined and economic levels of leakage targets were developed and adopted. In 1997 the UK's Water Regulator set mandatory targets for the water companies to achieve and each company has had to submit detailed calculations of their assessment of economic levels of leakage. Inevitably these submissions are rigorously challenged by the Regulator, but in the case of MKW, their recent targets were accepted and have now been achieved. For WBL, although not regulated like companies in the UK, water shortages in Cyprus have driven the need to reduce leakage/NRW and similarly the organisation has needed to set stringent targets in order to be able to provide an adequate water supply to their customers. The development and ongoing refmement of the leakage/NRW strategies within MKW and WBL, include several key components which are summarised below followed by a brief account of the results of this strategy for each of the two organisations:
2. Leakage/NRW reduction strategy Although both the Water Board of Lemesos (WBL) and Mid Kent Water pie (MKW) had operated an "active" leakage/NRW reduction
2.1. Manpower
It is most important to have well trained and motivated staff on leakage/NRW activities and
C. Charalambous, M. SeOCord/Desalination 138 (2001) 41-46 within both organisations a dedicated leakage control team was formed to tackle this vitally important area of work. Previously, the task formed part of the duties of multi-disciplined inspectorate teams. These manpower levels have been monitored against leakage levels and performance over the years to ensure staff levels have been both adequate and appropriate to fulfil the leakage/NRW reduction targets. 2.2. Flow monitoring In order to be able to work with confidence using the raw data provided from a system, it is very important for meter accuracy to be reliable from the waterworks source works through to the individual customer. A great deal of effort has therefore been expended in ensuring the reliability of this information, including meter replacement programmes and intensive calibration exercises. In addition, programmes of district metering were given high priority and the whole of the two organisations areas have now been broken down into District Metered Areas ranging between around 1000 to 3000 properties and these are continuously monitored using logging devices. Information on night-flow in particular is useful to the leakage practitioners who use the details to prioritise their leak location/management. 2.3. Pressure management High pressures within distribution systems are one of the primary causes of leaks and bursts, therefore managing the pressures on the system is a vitally important activity. Using various types of pressure reducing valves on the inlets to distribution systems, pressures can be managed in order to minimise the damage that might be caused. The investment by the two organisations on this activity has had a very significant effect on the reduction of the overall level of leakage/NRW.
43
2.4. Leak location Having prioritised areas for leak location from night flow data, the leakage teams then need to precisely locate the leak positions, which in the past has been undertaken by staff using various pieces of equipment including the basic "listening stick". However, advanced technology is now available to assist with this activity such as the use of acoustic loggers and specialist leak correlation equipment. Using this equipment, operatives can pinpoint leak positions very accurately and usually to within 0.5m. Following this activity, the leak repair teams can then be called and a repair effected. Over the years, both organisations have steadily increased their investment in modem technology and equipment. 2.5. Speed of repairs The primary aspect of a leak repair is that it should be carried out as quickly and safely as possible in order to maximise the savings and also of course, reduce the inconvenience to customers. Specific targets have been developed by MKW and WBL for repair work and these are regularly reviewed.
2. 6. Asset replacements By adopting an effective leakage/NRW reduction strategy, organisations can defer significant levels of capital expenditure particularly of resource development, including of course desalination projects. However, it is most important to link the asset replacement programme to the leakage/NRW strategy including in particular, pipeline replacements. It is also important to consider service pipe replacements, as it has recently become more apparent to people associated with this particular activity, that a significant proportion of leakage from distribution systems comes from service pipes and their associated fittings.
44
C Charalambous, M. SeOCord/Desalination 138 (2001) 41-46
2. 7. Reduction o f apparent losses
At the early stages of leakage/NRW reduction programmes, meter change-out programmes need to be developed, particularly for large commercial customers. This is necessary because old mechanical meters under-record to varying degrees (typically 3 to 15%) which inevitably reduces revenue to the water undertaking. Thus a meter change-out programme has the combined benefit of producing more reliable information for the Leakage/NRW teams and also increased revenue for the organisation as meters changed out, invariably under-record.
3. Case study 1 - Mid Kent W a t e r pie
Mid Kent Water plc is one of 16 water supply only companies within the UK, covering the South East of England and supplying on average, around 165,000m3/d of potable water to a total population of approximately 570,000 (comparable with the overall population of Cyprus). The company's origins date back to 1888 and the operational area is now 2050km 2. The area is generally rural in nature with five large townships, with the largest population of a single town being approximately 100,000. There are 4200km of pipelines, 100 operational boreholes, 33 treatment works and 74 storage reservoirs. The raw water resources emanate predominantly from underground (90%) with the remainder being provided by surface water from impounding reservoirs. It was in 1989, that the water industry within the UK became privatised and regulated by a government body called OFWAT. Following the introduction of regulation, greater emphasis was put on the activity of NRW reduction by all water companies within the UK. As a result of this pressure on the UK's Water Industry, a National Leakage Initiative body was formed which, following extensive field trials across the UK, culminated in a number of procedural
documents being developed for the various activities of this vital activity (for information, the English author was a founder member of the Steering Group to this particular body). By adopting the strategy detailed in section 2 above, the company reduced the leakage/NRW from a maximum recorded in 1987 of 47,000mVd (around 33% of total losses) to a current audited level of 29,200 mVd (around 17% of total input). This overall reduction represents a water saving that would supply an average town with a population of around 100,000 and a financial saving of£500,000 per year based upon operating costs alone. In addition, significant financial savings have been achieved as a result of the deferment of several resource development schemes. These results were achieved not only by adopting the strategy detailed in section 2 above, but also by the introduction of component based computer models such as BABE (Bursts and Background Estimates). Mid Kent were the first company in the world (together with the developer of the concepts) to use this methodology, which revolutionised their whole approach to leakage/NRW reduction. A dedicated leakage team comprising 18 staff and many other support staff developed 360 individual District Metered Areas and increased the coverage of pressure control from 20% to 60% (by area of the company). In addition, a regular programme of mains and service pipe replacements was adopted together with a rigorous meter replacement programme. If the company had not made these significant changes, not only would they have suffered severe f'mancial penalties but also, they would not have been able to sustain a continuous reliable water supply to their customers. 4. Case study 2 - Water Board o f Lemesos
The town of Lemesos is situated on the south coast of the island of Cyprus in the north-eastern
C. Charalambous, M. Setford / Desalination 138 (2001) 41-46
Mediterranean Sea, has a current population of 150,000, and is the second largest town of the island. The Water Board of Lemesos is a non-profit, semi-government organisation charged with the responsibility of supplying potable water to the town and environs of Lemesos. The Water Board was established in 1951 and as the town of Lemesos expanded, absorbing adjacent villages, the supply boundaries of the Water Board progressively moved outwards. Today the Water Board covers an area of some 65 km 2 with 674 km of underground mains. The Water Board of Lemesos is the owner of wellfields, storage reservoirs, pumping stations and underground water distribution network comprising pipelines, isolating valves, air valves, washouts, fire hydrants and house connections. The main activities of the Water Board include inter-alia planning and execution of technical projects, operation and maintenance of the water production and water supply systems and all associated financial services including collection of water revenues and determination of water tariffs. The Water Board operates a well-organised supply and distribution system with permanent pressure zones and District Metered Areas which provide a solid foundation on which to develop an effective leakage control policy. Based on the studies carded out in 1996 by Halcrow Water Services Ltd of UK, it was estimated that the Non Revenue Water figure of 19% consisted of approximately 15% leakage and 4% customer meter under-registration. Analysis of water balance data showed that virtually all the unaccounted-for water occurred within the districts, not on trunk mains. The annual total of locatable leakage was estimated to be 935.000m 3 with an annual cost value of US$500,000. The value of lost revenue through meter under-registration was estimated to be US$350,000. These initial findings had to be verified through further investigations.
45
Furthermore it was strongly recommended that a system of continuous monitoring be established in every District to analyse nightlines on a weekly basis. It was also recommended that a dedicated leakage team should be established to carry out active leakage detection in all the Districts using leakage correlation equipment. Following the above study a permanent leakage team was established in late 1998 and leakage detection and correlation equipment was purchased at the beginning of 1999. Also at this time, monitoring work commenced on a continuous basis. During 1999, a total of 41 leaks were detected and repaired, saving an estimated 140,000 m 3 of water, which would have cost the Water Board approximately US$70,000.
5. Conclusions
Demand forecasts for both MKW and WBL show a steady increase over the coming years and leakage reduction strategies as outlined above will go a long way towards offsetting this demand increase. It is important to appreciate, that any leakage/NRW strategy is a "non-stop" activity, which needs to be embraced fully by the organisation at the highest level and throughout the workforce, in order to be able to reduce the amount of water lost and maintain NRW at an economic level. We believe that both of the above organisations have achieved a great deal over the years, as can be seen from Figs. 1 and 2 and these results compare very favourably with NRW levels in other major organisations around the world, as can be seen in Fig. 3. It is clear, that the implementation of an appropriate NRW strategy within any water supply organisation, can greatly contribute towards more efficient and effective management of the available water resources, especially in parts of the world where water scarcity is a problem.
C. Charalambous, M. Setford / Desalination 138 (2001) 41-46
46
5O
oi 70
60 ~
_ I
_Ill oli|
40 so
2O 10 0
i~ 10
~.,
,.
v,
-
~1 ~.
v
-
0
,,n
0
.~
", _0
m
.--
E
~,
Fig. 1. Mid Kent Water NRW performance. Fig. 3. NRW performance by water undertakings worldwide.
30 25 20 ~15, 10, 5 O, i n oD
o~ YEARS
Fig. 2. Water Board of Lemesos NRW performance.
Footnote: With the knowledge and experience gained from the successful leakage/NRW Reduction programme in MKW over many years, Halcrow Water Services (a joint venture company between MKW and the Halcrow Group) are now providing specialist services in this field to organisations in several parts of the World. They combine the use of specialist software to develop and monitor strategies, with the use of state of the art equipment and techniques to reduce leakage/NRW to economic levels.