Formationof a Practical and Informative Management and Public Communication Tool

forInformation on Drinking Water Quality

ReportNo WSAA 143

September 1998




Informationon drinking water quality often involves the collection of a wide range ofmicrobiological and physico-chemical characteristics. This wide range ofcharacteristics makes it difficult to present the information on drinking waterquality in a summary form, suitable for:


·        Management decision making

·        Communicating with the public


Similarlycomplex economic information has been successfully summarised in the form of anindex (e.g. the Consumer Price Index for goods and services, and the AllOrdinaries Index for stocks).


Thisproject investigated if it was possible to use an indexing process for thepresentation of summary information on drinking water quality. In particular,the project investigated the formation of a practical and informativemanagement and public communication tool for information on drinking waterquality.


Theproject identified and addressed the main issues that impacted upon theformulation of a drinking water index, such as:


·        The importance of the microbiological measures of water quality in anyproposed index.


·        The need for an index that was:

-         Specific enough to beable to accommodate local variability, and allow each drinking water authorityto ‘create’ an index that best addressed their particular needs and concerns.Such an index had to be able to provide answers to such questions as:


¨       Generally, isdrinking water quality better in part A of the system, as opposed to part B?

¨       Generally, isdrinking water quality better this year than last year?

¨       Generally, isdrinking water quality better this season than last season?

¨       Generally, hasdrinking water quality improved since change X was implemented



-       General enough to be applicable in many differentdrinking water distribution systems, and allow different drinking waterauthorities to use the same indexing procedures. Such an index had to be ableto provide answers to such questions as:


¨       Generally, isdrinking water quality better in one system than another.


Theproject suggests the formation of a:


-       A specific index with the following characteristics:

¨       Total of 100points (based on the relative information value of the various parameters inthe index).

¨       Pass/fail valueof 50 points.

¨       Microbiologicalcharacteristics contributing 60 points to the total score (consisting ofparameters specifically selected for the particular system).

¨       A list ofparameters suited to the needs of each particular drinking water authority.


-       A general index with the same characteristics as the abovementionedspecific index, but with a standard set of 6 water quality characteristics (2microbiological and 4 physico-chemical) which are monitored by most drinkingwater authorities.


Thereport discusses the use of the proposed drinking water index in terms of:

-         Management decision making

-         Communicating with the public.


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