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Water Association
© 2014 Inter-American Development Bank
AquaRating: An Overview
1
DEFINITION AND OBJECTIVES
AquaRating is a rating system for drinking water and wastewater utilities
developed as an initiative of the Inter-American Development Bank (IDB) with
the collaboration of the International Water Association (IWA). The basic objective
of this system is the integral assessment of water and wastewater utilities
through 113 assessment elements organized in 8 areas, each one of which is
assigned a rating, ratings which in turn are aggregated into a unique rating (from
0 to 100, named AquaRating) for the utility. Assessment elements consist of good
practices and indicators. The total compliance with practices and achievement of
the most demanding indicators levels means delivery of an excellent service and,
therefore, awards a maximum rating of 100 points.
AquaRating seeks the improvement of the service
delivered by drinking water and wastewater utilities
by means of a rigorous and systematic assessment.
Therefore, it not only offers a rating of the service, but
it also provides opportunities for its improvement,
starting from the disaggregated information of the
factors used to determine the rating and the values
reached by each one. Thus it enables to establish
action plans in the areas for improvement
identified from such rating.
AquaRating will be operated by an independent
entity based on a model of financial self-sufficiency
which means that utilities (or a sponsor) must
cover rating costs. The rating will be voluntarily
requested by the utilities, the information collected
for rating purposes will be confidential and it will be
at the discretion of the operator's decision to make
it publicly available.
In order to guarantee AquaRating’s credibility and
to determine reliability of the supplied information,
all the information that leads to the calculation of
the final rating must be supported by documents
and validated by an audit. This audit, which will
¹ Visit also www.aquarating.org for more information.
take place after a previous self-assessment by the
utility, will be carried out by auditors certified by
the AquaRating Entity.
The entire process management, supply of data
and of supporting information by the utilities,
self-assessment and audit follow up will be carried
out by means of a safe website, which will be
accessible only by the utility, the auditor and the
AquaRating Entity. The website will allow the utility
to get a first rating while awaiting the validation of
the same after the auditing process.
The system has been designed to assess utilities
which deliver services mainly in urban areas,
located anywhere in the world. The expected
users of AquaRating are basically drinking water
and wastewater utilities. It is expected also that the
system could be useful for multilateral institutions,
regulators, public authorities and other sector
stakeholders, since it will let them know in an
objective way and in accordance with a known
rating structure, the rating of the main elements
of service management in an area and by a
given utility.
CONCEPT
AquaRating presents some important differences as compared to existing initiatives in the sector of drinking
water and wastewater services with similar objectives. Even though, from the outset, the team in charge of
the system’s design took into account international standards and existing projects, the truth is that the initial
conditions imposed on AquaRating could only have as a consequence a unique design until now. The main
requirements for the development of the system were the following:
•
•
•
•
•
•
Universality (validity in any context)
Integral assessment (it includes all areas relevant to performance)
Auditability
Guarantee of complete utility rating through indicators and practices
Ability to assess current performance and improvement potential
Ability to provide information for utility improvement
In order to address the above mentioned requirements, AquaRating consists of two types of assessment elements:
1) Indicators: Based on IWA established guidelines and on ISO 24500 standards, AquaRating
indicators are accompanied by an objective function that allows establishing the rating for that
element.
2) Good practices: For each concept to be assessed, AquaRating presents a collection of good
practices which characterize utilities with excellent performance. The utility’s rating depends on
the number of practices implemented in the assessed service.
The inclusion of good practices as an assessment tool allows satisfying several of the design principles. On
the one hand, good practices are less sensitive to context. By assessing the way in which utilities are managed
and not only the numerical outcomes of this management, the geographical, economic and social differences
do not have as high an influence on the assessment as they would do it on a pure assessment based on
indicators. On the other hand, practices enable to establish a projection to the future for the utility. A utility
currently in a good situation but lacking good practices may face sustainability problems. A utility with a low
performance but good management practices will surely improve in the future. Finally, a virtue of the good
practices included in AquaRating, and which was highlighted by operators invited to the system’s
development meetings, is that they, by themselves, are a guide for improvement, since those practices not
implemented by the utility may become its short and medium-term objectives.
The last, and essential, piece of AquaRating is its audit system and guarantee of the quality information. Data
quality has been recognized in many indicator systems as a cornerstone for validating assessment in a sector
in which, because of its nature, the reliability of the information may be very variable. Good quality
information in a drinking water and wastewater utility is not fortuitous, but the result of planning and of
adequate data management. Hence, AquaRating assesses the quality of supporting information and modifies
the rating as a function of that quality.
SYSTEM STRUCTURE
AquaRating is structured in 8 rating areas:
CS
EO
SF
GC
Service
Quality
Operting
Efficiency
Financial
Sustainability
Corporate
Governace
Efficiency in
the Planning
and
Execution of
Investments
EP
Business
Management
Efficiency
Access to
Service
Environmental
Sustainability
EG
AS
SA
RELIABILITY
Fig. 1. AquaRating
rating areas
Each rating area is divided into sub-areas. Thus, for example, the “Service Quality Area” is subdivided in 4
sub-areas:
Service
Quality Area
(CS)
Fig. 2. Service Quality
area hierarchy
CS1
Drinking water quality
CS2
Distribution of drinking water for use and consumption
CS3
Wastewater collection
CS4
User service
The assessment elements necessary for rating can be found in each one of the aforementioned sub-areas.
Each sub-area may contain elements of good practices, indicators or both. The system assesses the reliability
of the supporting data for each one of the assessment elements and modifies the element’s rating according
to that quality by means of a correction factor.
Rating for each one of the areas is obtained by a weighted aggregate of all the elements that are
hierarchically below. Thus, starting from the assessment elements, each level of the AquaRating system is
assigned a rating that goes from 0 to 100. These ratings are weighted within the same level with previously
determined weights, such that each area and sub-area gets a rating, from 0 to 100, resulting from the
combination of those elements.
In order to get a rating for each element from 0 to 100, it is necessary to normalize the results of each
individual assessment. In the case of lists of good practices, each of those practices has a relative importance
in relation to the rest (score). If all practices are complied with, that supposes a 100 for said assessment
element, while any partial compliance will result in a proportional reduction of the rating as a function of
the score of the practice non-complied with.
CS1 / Drinking Water Quality
Practices
Indicators
CS1.1 / Assurance of the
structural capacity for the
treatment and supply
CS1.4 / Operational structural
capacity for drinking water
treatment
CS1.2 / Assurance of water supply
with an adequate quality
CS1.5 / Compliance with drinking
water standards
CS1.3 / Supervision and control
CS1.6 / Supervision and control of
supplied water quality
Fig. 3 . Assessment elements for
the CS1 Drinking Water Quality
sub-area
EXAMPLE OF GOOD PRACTICES
Practices
Scores
1
Protection measures exist in the raw water intakes (signage, perimeter
protection, fencing, etc.) for sources of raw water of the system being rated.
1
2
Protocols exist for “preventive maintenance” actions in treatment plants,
and records of the same.
1
3
Protocols exist for “corrective maintenance” actions in treatment plants,
and records of the same.
1
4
There are automated processes in the treatment plants for running them in
absence of the staff (or personnel during 24 hours).
3
5
Protocols exist for the analysis and resolution of noncompliance with “applicable
standards” regarding water quality with notification to the competent authority.
2
6
Safety plans exist for “contingencies“ regarding water quality.
1
7
Protocols exist related to the assurance of water quality at the start-up of
new supply sources (wells or surface water).
1
8
Protocols exist related to the assurance of water quality in the integration
of new infrastructures.
1
Fig. 4. List of good practices for the CS1.2 element
Assurance of water supply with an adequate quality
In the case of indicators, normalization is accomplished by means of an objective function which marks the
desired values for each indicator. Said functions present the indicator value in the abscissa axis and the
normalized AquaRating value in the ordinate axis. It may be observed in Figure 5 that the percentage of
compliance with drinking water standards (% of samples which comply) yields a normalized value of 0 for an
80% of correct samples. A 92% of samples yield a normalized value under 30, whereas a 99% of the samples
yield the maximum score of 100.
NORMALIZED VALUE
Normalization function
100
90
80
70
60
50
40
30
20
10
101
100
99
98
97
96
95
94
93
92
91
90
89
88
87
86
85
84
83
82
81
80
79
78
0
NON NORMALIZED VALUE
NORMALIZATION FUNCTION
Fig. 5. Normalization function for the CS1.5 indicator
Compliance with drinking water standards
As it has been commented, the aggregation of ratings at each level is carried out by adding the weighted
ratings of all elements in that level. Because of this, each rated element has a unique pre-assigned weight in
the system. Figure 6 shows how the different elements of a level determine the successive rating of
sub-areas, areas and of the utility (AquaRating).
W1
W1
Area 1
W2
W_01
Sub-area 1
W2
Element 1
W_02
Area 2
Sub-area 2
Element 2
-
-
-
AquaRating
W8
Wn
Area 8
Fig. 6. Weighted aggregation of the different
ratings by level to achieve the AquaRating
W_On
Sub-area n
Element n
AquaRating An Overview
© 2014 Inter-American Development Bank