IWA World Water Congress &amp; Exhibition, Tokyo, JPN, 16-/09/2018 - 21/09/2018International audienceWith the aim of improving the implementation and evaluation of public policy in France relating to sustainable drinking water asset management (regulation at national level and subsidies at watershed level) the French Ministry of Ecology asked Irstea, a state research body, to create an ongoing system to manage technical and financial knowledge relating to drinking water network assets. In this study we develop a statistical approach to model pipe length by category, based on the geographical characteristics of the territory in which they are installed. Multivariate models including road length have been found to be pertinent. This technical analysis is accompanied by a study of asset values and renewal costs, based on a typology of water suppliers and an examination of economic and financial ratios. A number of disparities between territories are highlighted

Husson, A.

Renaud, E.

Rulleau, B.

Vacelet, A.

Wittner, C.

English

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Enhancing asset knowledge to improve French public
policies for sustainable drinking water asset management
E. Renaud, B. Rulleau, A. Husson, A. Vacelet, C. Wittner
To cite this version:
E. Renaud, B. Rulleau, A. Husson, A. Vacelet, C. Wittner. Enhancing asset knowledge to improve
French public policies for sustainable drinking water asset management. IWA World Water Congress
& Exhibition, Sep 2018, Tokyo, Japan. ￿hal-02267205￿
  
Enhancing asset knowledge to improve French public 
policies for sustainable drinking water asset management 
E. Renaud*, B. Rulleau*, A. Husson*, A. Vacelet*, C. Wittner** 
* Irstea Bordeaux 50 avenue de Verdun, Gazinet 33612 CESTAS Cedex, eddy.renaud@irstea.fr,  
benedicte.rulleau@irstea.fr, alain.husson@irstea.fr, alice.vacelet@irstea.fr   
** UMR GESTE 1, quai Koch  BP 61039 67070 Strasbourg Cedex, 
 christophe.wittner@engees.unistra.fr  
 
Abstract: With the aim of improving the implementation and evaluation of public policy in France 
relating to sustainable drinking water asset management (regulation at national level and subsidies at 
watershed level) the French Ministry of Ecology asked Irstea, a state research body, to create an 
ongoing system to manage technical and financial knowledge relating to drinking water network assets. 
In this study we develop a statistical approach to model pipe length by category, based on the 
geographical characteristics of the territory in which they are installed. Multivariate models including 
road length have been found to be pertinent. This technical analysis is accompanied by a study of asset 
values and renewal costs, based on a typology of water suppliers and an examination of economic and 
financial ratios. A number of disparities between territories are highlighted. 
 
Keywords: sustainable asset management; drinking water networks; technical and financial asset 
knowledge 
 
 
 
Introduction 
Asset management policies for drinking water networks are mainly applied at network 
level. However, the scope of these policies covers a much larger scale, particularly 
when it comes to water preservation through leak reduction. In France, the two main 
instruments used by public authorities to encourage water suppliers to apply 
sustainable asset management are regulation (at national level) and subsidies (at 
watershed level). At present, knowledge of networks and their financial value at both 
of these scales is insufficient to allow thorough optimisation of these policies. As in 
other countries (United States – EPA, 2013), (Denmark – DANVA, 2010) there have 
been previous studies into asset knowledge at national level in France (Ernst & 
Young, 2012), (Wittner, 2013), (EauFrance, 2015). However, none of the methods 
proposed exhibit a sufficiently strong combination of detail, precision, and 
reproducibility to allow reliable use and regular data updates.  
Since 2010, French water suppliers have been legally required to provide detailed 
descriptions of their networks. Creating these descriptions provides an opportunity to 
improve network knowledge. At the request of the French Ministry for Ecology and 
AFB (governmental water agency) Irstea is working on a method to enhance technical 
and financial asset knowledge at both national and watershed level. This article 
presents the methods, initial results, and future perspectives of our study, which began 
in 2016 and is planned for completion in 2018. The first part of our method involves 
carrying out an inventory of pipes at national level, while the second phase examines 
economic and financial aspects. 
Material and Methods 
Technical inventory of drinking water networks 
At the present time, it is not possible to access a full and exhaustive inventory of all of 
France's 13,500 drinking water networks. Only half of these suppliers declare the full 
  
length of their networks in the national database, which itself does not contain any 
data relating to pipe material, diameter or installation date.  
Our method involves searching for links between available information relating to 
networks and nationwide geographical and demographic data, to create statistical 
extrapolation models (Figure 1). The first stage in this process is to estimate total 
network length, mainly by making use of the significant link between pipe length and 
road length. 
 
Figure 1 Principle of statistical modelling 
 
Financial and economic evaluation of assets 
We estimate the value of French assets by identifying correlations between the unit 
price of individual assets and various criteria, thus constructing a typology of 
networks (Figure 2). This allows us to estimate the financial value of those assets, 
taking into account differences between urban and rural areas, areas with high and 
low levels of consumption, tourist and non-tourist areas, areas in mainland France and 
French overseas territories, etc.  
We then analyse disparities in the finance capacity of different WSSs by using 
different ratios, such as the ratio of asset value to annual self-finance capability. This 
provides a measurement of the time required to finance, from own resources, the 
capital tied up in assets. 
 
Figure 2 Approach developed to estimate asset replacement value 
 
  
Results 
Models to estimate total length  
The main data used to calibrate the model are on one side geographical characteristics 
and length of 5,043 drinking water networks, and on the other side, geographical 
information relating to roads, land use type, dwellings, and population information, 
available in the form of GIS layers for the whole of France. Exploratory studies, 
carried out on WSSs for which a detailed GIS plan was available, showed a clear link 
between pipe network layouts and road layouts. 
To account for the fact that some rural roads have no nearby pipes, we used a 
spatial processing method to include only sections of road located close to housing. 
Large-scale tests showed that the correlation between pipe length and road length is 
greatest when buffer areas are applied in a radius of 250m around each house (Figure 
3). 
 
Figure 3 Water network length based on road length after processing (Han-Mui, 2016) 
 
Following this, we created a number of multi-linear models, the accuracy of which 
was tested with the Monte Carlo method, using some of the available data for 
calibration and the rest for validation. The final models we selected use road length 
(corrected as mentioned above) population density, housing density, and inclusion in 
a particular watershed. Using this method, we estimate the total length of pipes in 
France to be 896,000 km (accurate to within 3%). 
Extrapolation of costs and analysis of disparities between asset values 
For the economic and financial part of our analysis, we use cost data (pipes, 
connections, fittings, ancillary costs such as pre-reception tests and project 
management, etc.) from the existing literature, as well as using information obtained 
directly from water suppliers. Based on this, we can create a table of unit prices by 
material type, diameter, connection density level, geographical area, and type of 
service. We then use the data in this table to carry out econometric analyses, allowing 
us to highlight correlations which can be used to create a typology. 
The initial results show that our more refined method is an effective way to estimate 
the financial value of assets. They also highlight disparities between different 
geographical areas, particularly between urban and rural areas.  
By comparing the time required to finance, from own resources, the capital tied up 
in assets and the price of drinking water, it is possible to examine the relevant scale 
  
and means of financing drinking water asset management policies while ensuring 
good quality service for users at an acceptable price. 
Conclusion and perspectives 
Estimation of pipe length based on correlations with corrected road length has 
provided good results. Models of the same type are currently being developed which 
will use a sample of networks in different geographical areas to include material type, 
diameter, and installation period in estimations. 
Our economic and financial approach allows us to create a typology of WSSs, as 
well as highlighting disparities between suppliers in their ability to finance pipe 
renewal at a price that is acceptable for users. Further work will involve applying the 
price table to estimations from the technical part of the model, allowing a calculation 
of network value and the finance required for renewal both at national and local level. 
References 
Cador, J.M. 2002 Le patrimoine en canalisations d'AEP en France - Bilan des huit 
enquêtes départementales et estimation nationale (French drinking water pipe assets: 
Summary of eight regional studies and national estimates). GEOPHEN, Université de 
Caen Basse-Normandie, Caen. 
DANVA 2010 Water in figures. DANVA’s benchmarking and water statistics, 
Skanderborg. 
EPA 2013 Drinking water infrastructures needs survey and assessment – First report 
to Congress. Drinking water protection Division, Office of Water, US EPA, 
Washington DC. 
Ernst & Young 2012 Etude de calcul de la récupération des coûts des services liés à 
l'utilisation de l'eau pour les bassins hydrographiques français en application de la 
directive cadre sur l'eau (Study of water service cost recovery for French watersheds 
based on the Water Framework Directive). Report to the Office International de l'Eau, 
Paris. 
EauFrance 2015 Observatoire des services publics d’eau et d’assainissement. 
Panorama des services et de leur performance en 2012 (Public water and sanitisation 
services: Overview of networks and their performance in 2012). Onema Vincennes 
France. 
Han-Mui, K. 2016 Etude des déterminants et modélisation de la consistance du 
patrimoine des réseaux d’eau potable. (Modelling the consistency of drinking water 
network assets). ENGEES Strasbourg France 
Wittner, C. 2013 Estimation des besoins de renouvellement des réseaux d’eau et 
d’assainissement collectif (Estimation of renewal requirements for collective water 
and sanitisation networks). Report to the Onema, Vincennes. 


Améliorer la connaissance du patrimoine en France pour une gestion durable du patrimoine des réseaux d'eau potable

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Améliorer la connaissance du patrimoine en France pour une gestion durable du patrimoine des réseaux d'eau potable

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