Report No FR0408

REVISION OF THE WHO GUIDELINES FOR DRINKING WATER QUALITY

FR0408

Sept 1993

SUMMARY

I BENEFITS

This work has provided a sound scientific and practical contribution to the revision of the WHO Guidelines for Drinking Water Quality which are likely to have a major influence on the proposed revision of the EC Drinking Water Directive.

II OBJECTIVES

To provide scientific support for, and to play an active role in the revision of the WHO Guidelines for Drinking Water Quality.

III REASONS

The WHO Guidelines for Drinking Water Quality are internationally recognised as a highly influential source of information for setting national and international drinking water standards. These, therefore, need to be regularly reviewed, revised and expanded in order to reflect the latest scientific and technical knowledge regarding contaminants in drinking water.

IV CONCLUSIONS

The current revision of the WHO Guidelines for Drinking Water Quality has been successfully completed and is proving to be a major influence on the development of standards in Europe.

V RECOMMENDATIONS

The intention is that WHO will review a number of parameters designated provisional in the near future. It is recommended that where appropriate WRc should play an active role in these evaluations.

VI RESUME OF CONTENTS

The process of the revision of the WHO Guidelines for Drinking Water Quality is described along with a number of key issues and parameters.

The Guidelines emphasise the importance of microbiological quality as the primary requirement for drinking water and will devote a significant proportion of the three volumes to the discussion and presentation of microbiological issues. The multiple barrier concept and the importance of E. coli as an indicator organism are re-affirmed.

There is a greatly extended range of chemical contaminants which are reviewed in the Guidelines with guideline values prepared where appropriate. In a change from the 1984 Guidelines no formal guideline values are presented for parameters affecting aesthetic quality although they are discussed in some detail. Changes in existing guidelines or guideline values for new substances which are likely to have implications for the UK are discussed. These include aluminium, asbestos, arsenic, boron, lead, chlorate and chlorite, bromate, THMs and chlorinated acetic acids.

The implementation of the Guidelines and the importance of taking local geographical, dietary and socio-economic conditions into account in incorporating guideline values into national standards is discussed.

Copies of the report are available from FWR, price 25.00, less 20% to FWR Members.