Benchmarking the Water Losses in Portugal

Transcription

1 Leakage 25 - Conference Proceedings Page 1 R C Marques*, R Gomes**, A J Monteiro*** * Rua da Várzea, no. 55, 3DT, Figueira da Foz, Portugal, rcmar@sapo.pt ** Morro do Lena, Alto Vieiro, Leiria, Portugal, rjgomes@portugalmail.pt *** Avenida Rovisco Pais, Lisbon, Portugal, ajm@civil.ist.utl.pt Keywords: Water losses; Benchmarking; Best practices Introduction Water losses are one of the main challenges that the water sector faces in most of the countries. High water losses have, above all, two notorious meanings. From one point of view, they imply an environmental loss and, from another point of view, they represent a relevant economic value in the annual profit and loss architecture of the water services. In Portugal this problem is particularly serious as, on one hand, the water losses value is significant, more than 35 % in the whole country on average and, on the other hand, the production cost is extremely high, with the majority of the water services buying bulk water to outside companies as a result of the reform the sector has been suffering in the last years with the separation between the wholesale water supply and the retail water supply. The bulk water service is usually provided by public companies which belong to the State while the municipalities are responsible for the water distribution. Besides, a significant part of the country, at least in the summer, presents lack of water resources. The water losses issue is, therefore, at the top of the water services, the Government, the NGOs and the economic agents priorities and it is starting to arise a generalised interest among the population. The study here presented came up as a need in the context of the current reality and corresponds to a research project that is taking place in two academic schools in Portugal about benchmarking application to ascertain the factors that contribute to the water losses and to identify the water services with best practices. This project has three main objectives. First, a complete survey regarding the water losses and the operation and maintenance practices that interfere with its value in Portugal is carried out. Until now there are no records neither any known studies doing this kind of analysis. Second, the sector is evaluated and the best market performances are determined. At last, it will try to find the routines and reasons that lead those water services to be the best practices. Benchmarking can be defined as a comparative process of some performance measure with a given reference standard. Its implementation becomes a key-tool to performance improvement in a natural monopoly scenario and when there is plenty of asymmetric information. In the water industry there are usually two kinds of benchmarking, respectively, process and metric benchmarking (Kingdom et al., 1996). The first phase of this project regards essentially the application of metric benchmarking. This kind of benchmarking enables the organizations to evaluate their performance over time and compare it with the one of other entities of similar characteristics and, in the majority of the cases, it is developed by means of performance indicators (PI). The work developed in this scope and that will be presented is two-fold, on one hand it applies the set of PI (Alegre et al., 2) which, directly or indirectly, are related to the water losses and, on the other hand, it uses a recent methodology (Marques, 25a) to determine the water losses total index (LTI) that enables us to rank the water services by their performance. This index, when compared to the PI, has as it main advantage the ability to deal with multiple inputs and outputs, allowing for the accomplishment of global performance measures. The LTI proposed can easily entail other aspects considered relevant by the water services individually. The PI are only able to analyse a single aspect at each time, which can generate incompatibilities and, eventually, present a distorted

2 Leakage 25 - Conference Proceedings Page 2 portrait of reality. By means of these two methodologies it is possible to identify the water services that present the best performance with regard to this aspect in Portugal. In the second phase of the research the results obtained are correlated with the several factors likely to justify or not the better or worse performance depicted. These aspects can be divided into two groups, one controllable by the water services and related to the operation and maintenance practices (e. g. preventive maintenance and meters replacement) and to the investment policy (e. g. assets age) and another related to noncontrollable factors as, for example, the service connections or customers density. This document is organized as follows. After this preamble, the water losses scenario in Portugal is described. Next, the case-study is introduced. First, the data collection and the methodology adopted based on an enquiry are described. Second, the results are rendered and then they are analysed according to several methodologies, in particular the performance indicators (PI), the regression methods, the efficiency matrices and the water losses total index (LTI). At last, the main conclusions are presented. Water Losses in Portugal In Portugal, as a result of the reforms taken in the middle of the 199s, the French model of organization and development of the water sector was favoured, although with some particularities, namely, the separation between bulk and distribution water with relevant consequences at the water losses level, the creation of a regulator for the sector and the appearance of the State as the main player in Portugal. 13 bulk water companies were created, which supply 188 water distribution services, comprising more than 6 % of the water supplied. These companies built, in general, new optimized systems, with higher feasibility and quality, which demanded high investments with repercussions in the customers bill. This was something that hadn t occurred before owing to the existence of high subsidization. Its impact in the production cost led the municipalities to give more attention to the water losses. Since then, the cost of the water losses started to be explicitly accounted, which didn t happen in the past, due to the lower production cost either because the water supplied and the service delivered had less quality or because it was concealed by other costs. With this reform there were municipalities whose production cost (water intake, treatment and transmission) represented less than 5% of the total and started to represent more than 5 %. This effect transformed the subject of the water losses into a key-issue for most of the water services. Besides, Portugal, like other South European countries, has been facing a severe drought for several months and the Government, together with the water services and some NGOs have been carrying out several sensitizing campaigns aiming at the efficient use of the water which cannot have effect near the citizens if the water losses level continues to be so high. Despite the concerns shown by different stakeholders, the scenario is not good, even because the results are not visible in the short run. In 23, the 3 water services existing in Portugal produced about 946 hm 3 of water, from which about 62 hm 3 regarded revenue water. In percentage, the average non-revenue water volume (NRW) was approximately 36 %, although this value can be higher, as around 25 % of the water services does not know for sure the water abstracted value (even though these are usually of small size) due to the lack of metering. Table 1.1 presents the main characteristics of the water sector in Portugal. Figures 1.1, 1.2, 1.3 and 1.4 represent, respectively, the NRW by each water service in percentage, by mains length per hour, by customer per day and by service connection per day. The values presented were based upon the APDA (Portuguese Association of the Water Services) data collection.

3 Leakage 25 - Conference Proceedings Page 3 Inhabitants (1 3 no.) Coverage level (%) Table 1.1 Main characteristics of the water industry in Portugal Distributed volume (hm 3 ) Revenue volume (hm 3 ) Domestic volume (hm 3 ) Water services (no.) Customers (1 3 no.) Mains (1 3 km) Staff (no.) ,56 62,77 414, , Non-revenue water (%) Non-revenue water (l km -1 h -1 ) Figure 1.1 NRW by water service (%) Figure 1.2 NRW by water service (l km -1 h -1 ) Non-revenue water (l cu -1 day -1 ) Non-revenue water (l SC -1 day -1 ) Figure 1.3 NRW by water service (l cu -1 day -1 ) Figure 1.4 NRW by water service (l sc -1 day -1 ) Several reasons, which will be discussed all over this paper, lie behind the high values of NRW, with emphasis on the very cheap water price subsidized by the municipal councils, the inefficient systems operation and maintenance, the construction problems, the lack of metering, the absence of pressure management and the inadequate commercial management, mainly with regard to the replacement and calibration of meters. An interesting aspect, which reflects the importance of the tariff policies, regards what happened in several municipal councils (e.g. Lagos) when they stopped to produce, themselves, the water they sold and started to buy bulk water. An almost immediate reduction of around 1% was noticed in the following years without major changes in the operation and maintenance practices, only avoiding the higher wastes. Case-Study Data In order to do this research about benchmarking application to control the water losses an enquiry was distributed to the 72 biggest water services in Portugal, covering about 6 % of the population. The information required and then used to compute the PI and to carry out the benchmarking exercise is displayed in table 1.2.

4 Leakage 25 - Conference Proceedings Page 4 Table 1.2 Main elements required to the water services Elements about the water services Volumes (abstracted, imported, exported, revenue and domestic) Customers Networks features (length, material, diameter and age) Service connections (SC) features (no. and material) Free delivered water volume and water suppliers consumption Water service total cost Elements about the water services operation Failures (number and type) Checks (number and type) Meters replacement SC replacement Mains replacement Unauthorized SC found Inspection of equipment, pipes and other network components Network maintenance Pressure control (maximum pressures) Active leakage control Previously, the water services were contacted and informed about this project, then an enquiry was sent and its reception confirmed and we let them know of our availability to fill it in. The information required was based, on one hand, on the existing knowledge about the Portuguese water sector (Marques, 1999), on works about water losses carried out in the past (Marques and Monteiro, 23) and, on the other hand, on the IWA standard terminology [(Lambert and Hirner, 2) and on its Best Practice manual (Alegre et al., 2)]. The elements asked by the enquiry refer to the years 23 and 24. From the 72 water services enquired, only 36 answered the questions asked. Even though, there was the possibility of including 14 more by a different means (Marques, 25b), which accounted 5 water services, covering 52 % of the Portuguese population. As it would be expected, the main difficulties were found in the mapping with regard to the mains age, their materials and the service connections features, the free delivered water volume and the water suppliers consumption. As far as the elements about the operation and maintenance activities were concerned, in most of the situations, the information was known but not always treated statistically. Table 1.3 systematizes the number of answers given. Table 1.3 Number of answers to the elements required Elements about the water services Volumes - 49 answers Customers - 5 answers Mains length - 5 answers Mains material - 36 answers Network age - 18 answers Number of SC - 31 answers SC material - 29 answers Free delivered water volume - 17 answers Water suppliers consumption - 24 answers Total cost of the water service - 5 answers Elements about the water services operation Number and type of failures - 4 and 14 answers Number and type of checks - 29 and 19 answers Meters replacement - 37 answers SC replacement - 21 answers Mains replacement - 28 answers Unauthorised consumption found - 15 answers Inspection of network components - 5 answers Network maintenance - 5 answers Network metering - 5 answers Pressures control - 5 answers Active leakage control - 5 answers

5 Leakage 25 - Conference Proceedings Page 5 Results The results obtained enable us to evaluate the water sector performance in Portugal regarding the water losses. The 5 systems involved in the research comprise a produced (distributed) volume of 555,8 hm 3 from which 373,5 are revenue water, corresponding to a NRW of 182,3 hm 3, that is 32,9 %. The domestic part of the revenue water corresponds, on average, to 66 % of the total, displaying extreme values of 48,4 % and 88,4 %. With reference to the mapping, we can stress the still high length of the asbestos cement mains with more than 24 % of the total. The polyvinyl chlorine mains length is about 48 %, whereas the polyethylene is 13 % and the ductile iron is 9 %. The mains are relatively recent as most of them are less than 2 years. However, there is a percentage that should not be disregarded with more than 4 years of age, corresponding to slightly 2 % of the total. The service connections material is diverse and there is still a high number of service connections made of cast iron and of lead. Usually the water services adopt one kind of material (polyvinyl chlorine or polyethylene) and they always use the same one. From the 17 water services that answered the question about the free delivered water volume 6 said it was zero. For the others the value ranged from,2 % to 5 % with an average of 2 % which concerned the water used for fire fighting, for watering the municipal gardens and for street cleaning. The consumption made by the water services themselves was between,1 % and 8 %, with an average of 1,2 %. The highest value of 8 % corresponded to an atypical situation of a water service that did not reuse the water from filters cleaning in the water treatment plant. The cost by cubic meter of revenue water varies between,44 and 2,28 with an average of 1,7. Table 1.4 presents the statistical features of the general elements required. Element enquired Table 1.4 Statistical features of the elements required Answers (no.) Average Standard deviation Minimum Maximum Median Distributed volume (m 3 ) Revenue volume (m 3 ) Domestic volume (m 3 ) Customers (no.) SC (no.) Length (km) Free deliv. water volume (m 3 ) Water suppliers consump. (m 3 ) Cost ( m -3 ) 5 1,7,39,44 2,28 1,9 The most relevant results concerning the elements about the systems operation and maintenance are described next. There is a very high number of failures, especially in the service connections, which represents more 7 % than in the mains. The number of maintenance checks is also abnormally high in most of the situations. There is a reduced value of unauthorised consumption with an average of 17 connections by water service. The average percentage of meters replacement by water service is 5,1 %, with extreme values of,5 % and 16,8 %. The average values of the service connections replaced is 2,4 %, with minimum and maximum values of 15,2 % and,1%, respectively and the ones regarding the replaced mains is 2,1 %, with extreme values of % and 17,8 %. From the 5 water services of the sample, 16 refer that they only carry out corrective (reactive) maintenance. 5 % inspect periodically the major network components, while 28 water

6 Leakage 25 - Conference Proceedings Page 6 services say that they do not inspect the other components (valves, hydrants, ) and 8 do it in a random way and occasionally. 27 water services do flow metering (in the network) besides the abstracted volume, but only 11 have specified metering points. 16 water services do not do any kind of control and management of the pressures and almost 5 % (24 operators) refer occasional problems of maximum pressures. 18 water services do an active control of water leakages. Table 1.5 shows this information. Table 1.6 presents the major PI computed with the information collected. Figures 1.5 to 1.8 represent graphically some of these indicators for each water service, respectively the NRW by mains length, the NRW by service connection, the number of failures by mains length and the number of failures by service connection. Table 1.5 Statistical features of the operation and maintenance elements asked Element asked Answers (no.) Average Standard deviation Minimum Maximum Median Failures (no.) Checks (no.) Unauthorised consumption (no.) Meters replacement (%) 37 5,1 3,7,5 16,8 4,4 SC replacement (%) 23 2,4 3,3,1 15,2 1,3 Mains replacement (%) 37 2,1 3,2, 17,8 1,1 NRW by mains length (l km -1 h -1 ) NRW by SC (l SC -1 day -1 ) Figure 1.5 NRW by mains length (l km -1 h -1 ) Figure 1.6 NRW by SC (l SC -1 day -1 )

7 Leakage 25 - Conference Proceedings Page 7 PI Table 1.6 Performance indicators (PI) results Answers (no.) Average Standard deviation Minimum Maximum Median NRW (%) 5 31,3 8,6 15,3 55,7 31,4 NRW (l km -1 h -1 ) NRW (l cu. -1 day -1 ) NRW (l SC. -1 day -1 ) NRW (l 1 SC. -1 y -1 ) Failures (no. 1-2 km -1 y-1) Failures (no. 1-3 SC -1 y -1 ) Mains failures (no. 1-2 km -1 y -1 ) SC failures (no. 1-3 SC -1 y -1 ) Checks (no. 1-2 km -1 y -1 ) Checks (no. 1-3 SC -1 y -1 ) Meters age (y) SC age (y) Mains age (y) Unauthorised (no. 1-3 cu. -1 ) consumption 15 2,3 3,6, 11,6 1, Failures by mains length (no. 1-2 km -1 y -1 ) Failures by SC (no. 1-3 SC -1 Y -1 ) Figure 1.7 Failures by mains length (no. 1-2 km -1 y -1 ) Figure 1.8 Failures by SC (no. 1-3 SC -1 y -1 ) Analysis of results The results obtained enable us to verify a significant improvement potential in Portugal with regard to the water losses. Inappropriate operation and maintenance practices, insufficient rehabilitation levels, inadequate pressure management and construction defects are some of the problems that became visible with the results presented above and whose upgrading will, naturally, enable the Portuguese water services performance enhancement. In the metric benchmarking studies the aim is, very often, such as here, to identify the organizations with best practices. Several methodologies are suggested in order to accomplish this. The first one deals with the comparison of the values obtained for the PI with optimal or reference values for each indicator. In Portugal, the Institute for the Regulation of Water and Solid Waste (IRAR), the sector s regulator, proposes reference values for the indicators they consider as the most important ones (IRAR, 25). In a previous study some reference values are also suggested for some of the water losses indicators

8 Leakage 25 - Conference Proceedings Page 8 presented (Marques, 1999). In this last study the results are sorted into classes, respectively, excellent, fair and poor, in accordance to the results (Marques and Monteiro, 21). In table 1.7 some indicators are rendered along with the reference values and the water services (from the fifty water services enquired sorted by decreasing number of inhabitants) that are benchmarks (as they have best practices) regarding the different aspects mentioned. PI Answers (no.) Table 1.7 Reference values Reference value (IRAR, 25) Reference value (Marques,1999) Water services that fulfil the reference values NRW (%) , 35 Failures (no. 1-2 km -1 y -1 ) 43 3 a 5 42 b, 5, 13, 3 SC replacement (%) ,5 1, 14, 21 c, 28, 34, 35, 37, 39 c, 41 Mains replacement (%) ,5 1, 3, 5 d, 6, 1, 11, 12, 14, 15, 19, 21 d, 23, 25, 28 d, 39, 45 a b includes other problems besides failures; < 3 failures by 1-2 km -1 y -1 ; c between 1,5 and 2 %; d between 1 and 1,5 %; Another performance analysis methodology, which follows the one presented, consists in the application of regression techniques to the different indicators leading to the average adjustment with regard to the diverse factors or indicators (Marques and Monteiro, 23). For instance, figure 1.9 illustrates this technique. The water services located below the regression curve are more efficient than the remaining as far as the aspects analysed are concerned and can be used as benchmarks. NRW by mains length (l km -1 h -1 ) Customers density (no. km -1 ) Figure 1.9 NRW versus customers density

9 Leakage 25 - Conference Proceedings Page 9 Y = 7,942X 49,663 (ρ 2 =,862) where: X represents the customers density (no. km -1 ); Y represents NRW per mains length (l km -1 hour -1 ) The PI analysis, despite being useful, of easy computation and of transparent meaning, can provide misleading and inconsistent indications when detached, as it only comprises one aspect at each time. The regression methodologies may include more descriptive factors (multiple regression), even though with only one dependent variable, which does not give them much supremacy. There are, however, some alternatives that despite being more complex are superior to a certain extent. One of them regards the construction of efficiency matrices. For example, instead of discussing which indicator is the best, if the NRW by mains length or the NRW by customer, with results, sometimes, incongruent, we can build the matrix represented in table 1.8. Table 1.8 Efficiency matrix of the water losses indicators A 3 22, 24, 34, 47 3 B 38 29, 49 13, 16, 19, 31, 37, 4, 5 18, 2, 33, NRW by length C 48 4, 26, 32 5, 15, 21, 27, 36 D 28 7, 12, 23, 25 1, 35 E 1, 9, 39, 46 2, 3, 8, 17, 41, 44, 45 11, 14 6, 42 E D C B A NRW by customer A More efficient; B Above average; C Average; D Below average; E Less efficient; In table 1.8 it was assumed that the water services could be classified into more efficient (NRW < 15 l km -1 h -1 and NRW < 75 l cu -1 day -1 ), above average (15 l km -1 h -1 < NRW < 3 l km -1 h -1 and 75 l cu -1 day -1 < NRW < 15 l cu -1 day -1 ), about average, (3 l km -1 h -1 < NRW < 45 l km -1 h -1 and 15 l cu -1 day -1 < NRW < 225 l cu -1 day -1 ), below average (45 l km -1 h -1 < NRW < 6 l km -1 h -1 and 225 l cu -1 day -1 < NRW < 3 l cu -1 day -1 ) and less efficient (NRW > 6 l km -1 h -1 and NRW > 3 l cu -1 day -1 ). Building efficiency matrices has some advantages when compared to the PI used individually. However, when they are used alone, they only take two factors into account, being, therefore, limiting, especially if we want to find the best practices of the sample. An alternative is the use of the water losses total index (LTI) that enables us to rank the water services by their performance (Marques, 25a). This index, when compared to the PI, has as its main advantage the ability to deal with multiple inputs and outputs, allowing for the accomplishment of global performance measures. This index is built considering the inputs, the outputs and the explanatory factors available for each reality and uses mathematical programming to determine the water services efficiency regarding the water

10 Leakage 25 - Conference Proceedings Page 1 losses, namely the non-parametric frontier technique of data envelopment analysis (DEA). The LTI, briefly introduced here, has several advantages, particularly, the identification of a group of efficient water services (peers) with a similar combination of inputs and outputs for each inefficient water service, to deal easily with multiple inputs and outputs, the adoption of the best results as comparison elements rather than the average values, the non-assumption of a functional form for the frontier or for the inefficiency when this is associated to the error, its conservative nature and the possibility of decomposing it into several components. Figure 1.1 shows the simplified model of the water losses. Network pressure O/M practices Customers NRW Water services Mains lenght Service connections Systems age Figure 1.1 Water losses model Table 1.9 shows the LTI results of the water services analysed. The LTI values range from to 1 and the score 1 represents the water services with best practices (efficient frontier) concerning the water losses. Two distinct situations were considered, including the existence of constant returns to scale (CRS) and of variable returns to scale (VRS). The pressures effect was not taken into account due to lack of elements. We adopted a second stage where we applied the Tobit regression in order to include the explanatory factors (Marques and Monteiro, 25a). The DEA algorithm related to the LTI applied here was computed by means of the software IN2DEA ( Besides the LTI (to CRS and VRS) we can also observe in the table the ranking of the results obtained by water service, arranged in decreasing order of size, as previously mentioned. This index based on DEA has the advantage of comprising several justifying factors of the water losses. The LTI also identifies the best practices and the peers that use similar combinations of inputs and outputs for each inefficient water service and establishes targets for each variable. The results stress that the existence of VRS is evident, which can be statistically proved by the stepwise method (Marques and Monteiro, 25b), that is, the water services of bigger size become clearly damaged. If we analysed, for example, the indicator NRW (%) and used the IRAR or Marques reference value of 2 % referred before, we would be unfair if we compared the water services 1 and 21, which present both this value of the indicator, but the second is almost half the size of the first, consequently being much more inefficient. Another very interesting aspect to be highlighted is that this methodology determines the ideal peers that can be used as benchmarks according to the characteristics of each water service. For example, the waters services 6 and 7 to VRS, which can reduce the input (NRW) in 63,8 % and 39,4 % still keeping the same production of their outputs, have as peers the water services 1 and 5 and 5 and 31, respectively.

11 Leakage 25 - Conference Proceedings Page 11 Table 1.9 LTI results and ranking of the water service studied Water service LTI (CRS) Ranking (CRS) Water service LTI (VRS) Ranking (VRS)

12 Leakage 25 - Conference Proceedings Page Average Concluding remarks This paper outlines part of a work that is still being done about benchmarking of the water losses in Portugal. It begins with some comments about the Portuguese situation in relation to this matter. After, it stresses the methodology followed to collect elements which consisted in the elaboration of an enquiry to study a set of water services representative of the country. The results that comprised 5 water services (52% of the population) are presented and discussed. The analysis of the results obtained in this first stage of the benchmarking research (metric benchmarking) followed several methodologies, namely the application of performance indicators (PI), the use of regression methods, the building of efficiency matrices and the determination of the water

13 Leakage 25 - Conference Proceedings Page 13 losses total index (LTI). The latter avoids some problems of the former ones, as it can analyse simultaneously more than one descriptive factor of the water losses. This article showed the long way that the Portuguese water services have to walk in order to attain water losses values closer to the best practices. In spite of the effort done over the past years and of the importance given to this matter by the water sector, some of the installed routines, such as the inappropriate operation and maintenance of the assets, the inadequate control and management of the networks pressure and the nonexistence of mapping and of information systems, have to be changed. References Alegre, H.; Hirner, W.; Baptista, J. and Parena, R. (2). Performance indicators for water supply services. Manual of Best Practice Series, International Water Association (IWA) Publishing, London, England. IRAR (21). Guide of performance evaluation of the water, sewerage and solid waste services. Institute for the Regulation of Water and Solid Waste (IRAR) and Civil Engineering National Laboratory (LNEC), Lisbon, Portugal (in Portuguese). Kingdom, B.; Knapp, J.; LaChange, P. and Olstein, M. (1996). Performance benchmarking for water utilities. AWWA Research Foundation and American Water Works Association (AWWA), Denver, Colorado, United States of America. Lambert A. and Hirner W. (2). Losses from water supply systems: standard terminology and recommended performance measures, IWA Website. Marques, R. (1999). Evaluation and management of water supply systems. M.Sc. thesis, Technology and Science School (FCTUC), University of Coimbra, Coimbra, Portugal (in Portuguese). Marques, R. (25a). The water losses total index. Concept and applications. Working paper, Management and Technology School (ESTG), Polytechnique Institute of Leiria (IPL), Leiria, Portugal (in progress). Marques, R. (25b). The water and sewerage services regulation. Application of non-parametric benchmarking techniques. Ph.D. thesis, Instituto Superior Técnico (IST), Technical University of Lisbon, Lisbon, Portugal (in Portuguese). Marques, R. and Monteiro, A. (21). Application of performance indicators in water utilities management - a case-study in Portugal. Wat. Sci. Tech. 44 (2/3), Marques, R. and Monteiro, A. (23). Application of performance indicators to control losses - results from the Portuguese water sector. Wat. Sup. 3 (1/2), Marques, R. and Monteiro, A. (25a). Technical efficiency of the water and sewerage services. An empirical study. In III International Conference Efficient Use and Management of Water for Urban Supply: Proceedings, International Water Association (IWA), March, Santiago, Chile. Marques, R. and Monteiro, A. (25b). Measuring the economic performance of the water services. A statistical non-parametric approach. In IWA International Conference on Water Economics, Statistics, and Finance: Proceedings [CD-ROM], International Water Association (IWA), 8-1 July, Rethymno, Crete, Greece.